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U.S.S.R. LIT!
V
RAPID METHODS FOR THE DETERMINATION OF
HARMFUL, GASES AND VAPORS IN THE AIR
A. V. Demidov and L. A. Mokhov "~
Translated
by
B. S. Levine, Ph. D.
This survey was supported by
PHS Research Grant AP—00176
Awarded by the
Division of Air Pollution, U. S. P. H. S.
Original publication by Medgiz, Moscow, 1962
Distributed by
U.S. DEPARTMENT OF COMMERCE
FEDERAL SCIENTIFIC AND TECHNICAL INFORMATION
Washington 25, D. C.
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OTHER TRANSLATIONS, BOOKS AND SURVEYS BY OR. 8. So LEVIHE OEAUHS WITH
USSR AIR AtS) WATER POLLUTION CONTROL AND RELATED OCCUPATIONAL DISEASES
ARE AVAILABLE FROM FEDERAL SCIENTIFIC AND TECHNICAL iKFORmTION,
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No,, PASES Pniez
LITERATURE on Am Poiumon ADD
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A SURVEY
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C01!VERS90a 7A08.ES ARE PHESStiTED 09
PAGES
-iii-
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TABLE OF CONTENTS
Page
Introduction ............... . .......... . ....................... \
The Bases of the Rapid. Methods ............................. ... 3
Collection of Air Samples to be Analyzed by
Rapid Determination Methods ................................ 4
Rapid Methods for the Determination of Inorganic
Substances in the Air ........................................ - 8
C arbon Monoxide (CO) ................................... 8
Nitrogen Oxides .................... ... .................. 16
Hydrogen Peroxide (H2O2) ............................. .. . . 24
Ozone- (O3) ................. ---------------- ............ _.._. ... _ 29...
Chlorine (C\s) . . . .................. ................ .' ..... 33
Hydrogen Chloride (HC1) .................. . .............. 39
Hydrogen Sulfide (HaS) ................................... 42
Carbon Bisulfide (CS2) ..................... . ..... ........ 47
Ammonia and Aliphatic Amines . .......................... 50
Arsenic Hydride or Arsine (AsH3) ......................... 55
Antimonous Hydride (SbH3) .. ..... ......................... 58
Fluorine (F2) ........................................... 60
Sulfur Dioxide (Sulfurous Anhydride,
or Sulfur Dioxide, SO2) ................................ 61
Mercury Vapor (Hg) . . .• ................................ . . 67
Hydrocyanic Acid (HCN) .............. . .................. 70
Nickel Tetracarbonyl C(Ni(CO)4] .......................... 75
Carbon Dioxide (COS) ..... ............................... 76
Rapid Methods for the Determination of Organic
Substances in the Air ....................................... 80
Formaldehyde (HCOH) ................................... 80
Ethyl Alcohol Vapor (C2H5dH) ______________________ ....... .. ...... 82
Liquid Fuel Vapor ................... ....... ............ 84
Phosgene (COCL,) . . ..................................... 89
Acetylene (C3H3) ........................................ 92
Benzene Vapor ...................................... ... 94
Ethylene Oxide (C3H4O) .................................. 95
Aniline (C6 H5NH3) .................. ..................... 96
Acetone (CH3-CO-CH3) .......... . ......... . ............. 98
Appendixes
Appendixes 1 and 2 ...................................... 99
Appendixes 3 and 4 ...................................... 100
Appendix 5 .......... . ...................... ............ 1Q1
Appendix 6 ............. . ...............................
Bibliography
-v-
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Translator's Foreword
Volume 10 of the survey series "U.S.S.R. Literature on
Air Pollution and Related Occupational Diseases" is a transla-
tion of A. V. Demidov's and L.A. Mokhov's book "Rapid Methods
for the Determination of Harmful Cases and Vapors in the Air"
MeTO^Bi Onpe^ejieHMH B Bosjtyxe Bpe^ntix M
BeujeCTB) , published by Medgiz of Moscow in
1962. The greater part of the outlined procedures had been
developed by U.S.S.R. analytical chemists, while some were
taken from literature of other countries. The collection of tests
appears to be intended primarily for the detection of dangerous
gaseous and vaporous air pollutants in indoor working premises
by sanitary inspection personnel and by those whose responsibil-
ity is workers' occupational safety. For each harmful gas or
vapor the authors present qualitative as well as closely approxi-
mate quantitative- p-r&eed-u-re-s-, to make possible the early deter-
mination of dangerous harmful gas and vapor concentrations in
the air of working premises and to forestall the occurrence of
serious accidents. The volume was also intended to meet the
needs of smaller laboratories and of field industrial laboratory
workers.
The plan of each procedure presentation is generally as
follows: The name of the gaseous or vaporous substance, its
chemical formula, its basic physical and chemical characteris-
tics, the nature of the chemical reactions which form the basis
of the test, the reagents and facilities required, the preparation
of the indicator, the preparation of standards of comparison, the
actual analytical procedures, and, where indicated, methods for
the calculation of the final results. Having in mind laboratories
which may have inadequate library facilities, or insufficiently
trained laboratory help, the authors supplemented the volume
with a series of appendixes, such as volume, percent, and
weight conversion formulas and tables, tables of ready calcu-
lated factors, specific gravity equivalent concentrations for
some acids, etc.
B.S. Levine, Ph.D.
-vi-
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INTRODUCTION
The tempo of industrial development in. the USSR is rapidly"accel-
erating. This is especially true o£ the chemical industry which is being
developed according to the plan of industrial growth outlined and adopted by
the September Plenum of the Central Committee of the USSR Communist
Party. The construction of plants and factories for the production and
processing of many new chemical substances is being expanded constantly.
Many of the new processes are characterized by the creation and discharge
of highly toxic by- and end-products. Parallel with this there arises the
problem of sanitary-hygienic danger to workers and the need fn* develop-
ing means and methods for the elimination of such dangers. The regula-
tions which have been incorporated into the USSR laws intended for the pro-
tection, of the health and welfare of workers served as the impetus in reduc-
ing the number of occupational diseases occurring in the different national
production and processing industries. Non-compliance with regulations
intended for the protection of workers' health may lead to dangerous health
effects through the inhalation of poisonous gases or vapors, through direct
contact of poisonous substances with, the v/orkers1 skin or mucous mem-
bxa.nes, through accidental swallowing or inhalation, thereby affecting the
normal conditions of the lungs or of the intestinal tract. Of the above
mentioned routes of possible workers' intoxication, the most frequent is
inhalation of harmful substances present in the air of production and
processing premises. It is the duty of toxicologists and sanitary-hygienists
to institute means and methods for the prevention of accidental poisoning.
This can be done only by first making preliminary investigations of condi-
tions surrounding a specific industrial process, including conditions of the
environment surrounding the workers in any particular plant or factory,
especially with respect to.the degree of air pollution with harmful gases,
vapors, or aerosols. The importance of the above is emphasized by the
fact that at present practically ail production processes involve some
phase of chemistry. It should also be noted that the greater part of inter-
mediary and end products of the chemical industry possess some degree
of harmful effect on the human organism. Therefore, it becomes impera-
tive that hygienists, industrial physicians, and laboratory workers who axe
concerned with problems of workers' health should have at their disposal,
means and methods for the rapid detection of the presence in the air and in
the general surroundings of toxic and otherwise harmful substances. Such
means and methods must be of high sensitivity, accuracy, simplicity and
rapidity of accomplishment.
-1-
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. . Literature is r.eplete with methods for the determination of foreign
substances and gases in the air. However, most of them cannot be used
under some technical conditions, especially where large numbers of
analyses must be performed in a comparatively short time. Much has
been accomplished recently in the direction of meeting the above mentioned
requirements; at present there exist many rapid chemical methods of air
analysis, and much work is being done in the direction of their further
perfection; Many of the rapid methods for the determination of harmful
gases and vapors in the air are based on the principle of indicator tubes
which contain appropriate types of reagents. As the air containing a toxic
or harmfo-l- ga-s=-or -va-p©* ts- pas-s-ed_thjiaugh_the indicator tube,__the specific
chemical indicator reagent acquires a color of .different intensities. Fre-
quently the tube contains filter paper saturated with the indicator reagent.
Determination or detection of harmful substances in the air by means of
indicator tubes is much more rapid and considerably simpler than by
methods requiring chemical analysis. Many of the rapid indicator tube
methods for the detection and determination of given air pollutants are
fully as sensitive and accurate as the complicated laboratory methods of
analysis. Due to their simplicity, rapidity, and portability such proce-
dures and methods of air analysis can be performed at any desired point
of a plant or factory or in the field at any stage of production. In this way,
it becomes possible to forestall serious accidents or to detect leakage of
toxic and harmful gases into the air before their concentrations in the air
reach the point of danger, so that the fault can be corrected without stop-
ping the plant production. Because of the above mentioned advantages many
authors recommend the wide use of the rapid methods, described by N. A.
Tananaev, L. M. Krasnyanskii, and others in literature of the USSR and
abroad.
In some sections of the USSR laboratory workers may not always have
access to such literature. Not infrequently such methods are described in
abstract form lacking the necessary details of the recommended proce-
dures. This created a need for the compilation, systemization and full
description of such methods for the convenience of laboratory workers,
especially for the smaller type of laboratories. The present volume is
intended to meet such need of industrial and analytical laboratory workers.
The present authors place at the disposal of laboratory workers not only
the narrow spectrum of rapid methods based on tubes containing indicators
in the form of saturated filter paper, silicagel, or other absorption materi-
al, but also methods based on the use of solution methods which are equally
simple and rapid. This volume also includes several qualitative and quan-
titative methods for the determination of any substance, taking into con-
sideration the fact that some laboratories may not have the reagents
required for a given qualitative and quantitative analytical procedure. In
addition, methods have been outlined for the preparation of reagents neces-
. sary for one or another of the procedures, and also for the preparation of
equipment and means of calculating the results.
-2-
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THE BASES OF THE RAPID METHODS
Practically all rapid metho.ds are based on the principle of color!-
metry. At first nearly all rapid methods used filter paper saturated with
a solution of one indicator reagent or another for the detection of the
presence of foreign harmful gases or vapors in the air. This principle has
many shortcomings when used in connection -with certain types of investiga-
tions. It was found that the filter paper procedure lacked sensitivity,
specificity and even accuracy. The filter paper indicator method is limited
at the present time almost exclusively to qualitative and.approximate quan-
titative determinations. Frequently such procedures involve a set of color
standards for the final evaluation of test results. Occasionally the paper
filter indicator method, as stated above, yields no specific results, due to
trie presence in tne air of a. coi'iioinciLiOii uf extraricuus substances, winch
may be of no concern to the analyst at the time. Under such conditions the
nonspecific reaction cannot be eliminated, due to the fact that the filter
paper indicator comes into direct contact with the tested air. The non-
specific reaction here referred to can be eliminated by the procedures des-
cribed on page 7, Par. 4. Tube indicator methods in which solid material
is employed as the absorbent, such as silicagel, alumogelj corundum,
kaolin, etc. are almost entirely free from the previously described short-
comings.
The solid sorbent is saturated with a suitable indicator, dried and
placed into a glass tube packed with glass wool at each end and is then
sealed hermitically. In making the analysis both sealed ends of the tube
are cut open with a glass file and the air passed through the tube. A color
change in the indicator saturated sorbent indicates the presence in the air
of the suspected impurity. Based on the method of recording quantitative
analytical results, rapid methods can be divided into colorimetric and
linear-colorimetric procedures. The linear-colorimetric procedures
necessitate the use of a color scale. In other instances, the following
quantitative estimation method can be used: the air is passed through an
indicator tube in a given volume; changes in color and intensity are then
compared with a color standard which indicates the relative percentage of
the toxic substance in the air. By using a. standard curve and locating
intersection points of the air volume passed through the tube and the corres-
ponding percentage of the reagent, the absolute percentage of the toxic sub-
stance in the air can be found on the plotted curve. Other principles for
the direct colorimetric determination of substances in the air will be des-
cribed later in the text.
The procedure of the linear colorimetric method is as follows: A
known volume of air is passed through the indicator tube per unit time;
change in the sorbent indicator color penetrates the sorbent indicator to a
-3-
-------
depth proportional to the concentration of the toxic substance under investi-
gation. Accordingly, the quantitative determination, that is the concentra-
tion of the toxic substance, can be arrived at by measuring the length of
the colored sorbent indicator in the tube. Final concentration of the toxic
substance is established by a calibrated curve previously constructed on
the basis of known experimental concentrations with the abscissa repre-
senting lengths of colored layer and points on the ordinate representing con-
centrations of the investigated substance. The linear colorimetric method
must be conducted with the strictest degree of care and accuracy to obtain
an absolutely even density distribution of the sorbent in the tube. It is also
imperative that tubes should be of equal length and equal diameter, and that
they contain equal amounts of the sorbent indicator. Lack of compliance
with these specific conditions may lead to inaccurate results. Therefore,
the present writers recommend that the direct colorimetric method should
be used in preference to the linear colorimetric method" as one which, is per-
formed easiest and which yielded most constant results.
Generally speaking, rapid indicator tube analyses have their value in
the fact that maximal color intensity of the indicator developed rapidly and
that if properly applied the results could be highly specific, i.e. by first
passing the air through substances which absorb and remove from the air
interfering admixtures. Another advantage is presented by the fact that the
tubes containing the silicagel, or any other solid sorbent, could be heated
to any desired temperature.
COLLECTION OF AIR SAMPLES TO BE ANALYZED
BY RAPID DETERMINATION METHODS
Air samples are usually collected into appropriate types of containers
from which the air is later transferred into graduated gas pipettes or small
aspirators, and the like. The air is passed from these containers directly
through the indicator tube in measured volume. This procedure has many
shortcomings; for instance, the air collected into rubber containers may
become partly adsorbed to the walls of the container; the use of aspirators
may not be proper for the collection of air samples which contain components
soluble in water. Other, so-called, simple methods of collecting air sam-
ples may have other shortcomings. Wherever possible air samples should
be collected by specially prepared devices from which the air can be con-
veniently passed through the indicator-containing tube in any desired volume.
It is important, however, that the volume passed through the indicator-
containing tube should be measured with a high degree of accuracy and that
the air should be passed through the indicator tube at a known even flow rate.
Such an apparatus, or device, must be of simple construction and of easy
portability. The following is a description of an apparatus which can be
-4-
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Figure 1
used conveniently for the purpose of rapid determination of toxic sub-
stances in the air both quantitatively and qualitatively.
1. The device for the purpose under consideration used in the Lenin-
grad All-Union Scientific-Research Institute for the Protection of Labor
(VTsSPS) is illustrated in Figure 1. The basic part of the device is a. col-
lapsible rubber bellows(l) inside of which is inserted a spring (2) which
keeps the rubber container
expanded. The upper lid of
the device has round openings
into which the indicator rube
(4) and a thermometer are
inserted; through a round
opening in the center of the
upper lid a hollow rod is
inserted which can be freely
moved. The glass rod is
widened at the top into a nail-
type head which prevents it
from falling through. By
applying pressure on the head
of the rod the rubber bag can
be compressed. Immediately
below the head of the rod there
is provision for recording the
type of gas pollutant and the
volume of aspirated air. By
means of a central hollow and
two depressions in rod (3) it
is possible to shorten the
collapsible rubber bag for the
purpose of taking in any de-
sired volume of air. The
device measures 112x112x214
mm and weighs 2. 5 kg and is
easily portable.
2. A portable apparatus for
passing air through an indica-
tor tube was proposed by V.A.
Khrustaleva and I. K. Yakovenko.
It is schematically presented in
Figure 2. It consists of a rub-
ber bulb (l) filled with water;
the bulb is connected with a
graduated pipette (2) by a
FIG. I. AIR SAMPLE TAXIffS APPARATUS.
JB3ER IELLOWS. 2. SPBINS. 3. ROD. 4. INBICATOR
TJJE.
-5-
-------
rubber tube (3); the graduated pipette (2) is equipped with ground-to-fit
stopcocks (4) and (5). When stopcocks (4) and (5) are opened with the
rubber bulb in its indicated position, the water flows out of bulb (l) and
completely fills the graduated pipette (2). Stopcock (4) is then closed and
the indicator tube is connected with graduated pipette (Z) by attaching it to
outlet (7) of stopcock (5) by a short rubber tube. Stopcock (4) is then again
opened, and rubber bulb (l) is lowered slowly
Figure 2 and gradually creating a negative pressure
which draws the tested air through the indica-
tor tube via opening (7) of stopcock (5). The
mark on the graduated pipette to which the
water drops at the time stopcock (4) is again
closed indicates the volume of air aspirated
through the indicator tube.
3. The analyzed air can also be aspirated
through the indicator tube by a simple device
described by I. F. Turov which is of the shape
of a small accordion. The operation principle
of this device can be easily discerned from the
schematic plan in Figure 3. The maximal total
capacity of the device is 2. 5 li. The device is
brought to the place of air sample collection in
a compressed condition and with stopcock (3)
closed. At the place of sample collection stop-
cock (3) is opened and the accordion expanded,
which causes the air to be sucked in through
open stopcock (3). The volume of air taken
into the device varies according to the length
to which the accordion has been expanded.
Figure 3
FlS. 2. PORTAJLE APPARATUS FOR
FORCING AIR THROUGH THE TUIE.
I. RUttEft lULi. 2. GRASUATEi
PIPETTE. 3. RuiIER TUIIN6.
4. TWO-WAY STOPCOCK.
5, THREE-WAY STOPCOCK.
6, 7. OUTLETS.
FIG. 3. APPARATUS FOR FORCING AIR THROUSH INDICATOR TUIE.
I. Sou» PLATE. 2. HANJLES. 3. 1 STAKE-OUTLET WITH
TWO-WAY 6TOPCOCK. 4. 3ELLOWS.
-6-
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Where more precise volume determination is required, the modified form
of this device, shown in Figure 4, can be conveniently employed in connec-
tion with indicators of different sensitivities which may require different
volumes of air for more precise determinations of the poisonous gas or
vapor concentration in the air. It is hoped that the schematic drawing
accompanied by the brief legend might be self-
Figure 4 explanatory with regard to the use of this device.
4. The device schematically illustrated in Fig. 5
was designed for use in connection with rapid
determinations of air and gas mixtures in which
the gas or vapor absorber was filter paper satu-
rated with the indicator solution. The device con-
sists of two funnel-shaped adapters, an upper
one (A) and a lcv.-cr one (B). The filter nappr is
placed between the adapters which are then tightly
fastened together, and the air aspirated through
the top opening of adapter (A) indicated by the
arrow. Whenever necessary the air can be
bubbled first through a special absorber solution
for the removal of interfering gas admixtures.
5. In making linear-colorimetric determinations
it may be desirable to use a device specially
designed by Jacobs, which is schematically illus-
trated in Figure 6. It is hoped that the schematic
drawing accompanied by a number of legends will
be adequate for the understanding of the way in
which this device can be used.
Figure 6
> i
FlS. 4. A MODIFIED PORTAJLE
APPARATUS FOR THE ASPIRATION
OF AIR SAMPLES.
I - VERTICAL HOLDINS RODS;
2- VOLUME DETERMINING ROD;
3 -• ACCORDION RUB«ES «A«,
Figure 5
FIG, 5. INDICATOR PAPER HOLBER.
A A.MS 3 - CONICAL METALLIC HOIBERS;
C - HOLOES HECKJ A - IIOLOES JUHCTIOH
LINE.
Ft-3. % ».?.»AS ATI'S FOR AIR ASPIRATION IN THE LINEAR
COLOSIMSTRIC METHOD.
I - METALLIC STAND; 2- RUUEH »UL§; 3 - INDICATOR TUIE;
4 - I^OVASLE EIID; 5 - SPRIHS; 6 - THREAD-ROB; 7 - THSEABEI
KNOT; 8- HOLE pea IVBICATOB TUIE; 9- STATIONARY ENB.
-7-
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RAPID METHODS FOR THE DETERMINATION OF
INORGANIC SUBSTANCES IN THE AIR
CARBON MONOXIDE (CO)
Carbon monoxide is a colorless and odorless gas which is soluble in
water only in 2. 5:LOO_ra±io_.by volume; it is nonreactive with water or with
alkalies and acids. The mol.wt. of carbon monoxide is 28.01, its molecular
volume is 22. 4. Its density in relation to air is 0. 9669. One cm3 of carbon
monoxide at 0° and 760 mm of mercury weighs 1. 25 mg.
Toxicology
Carbon monoxide is a highly toxic gas. Its toxicity is due primarily
to the fact that it combines with blood hemoglobin forming carboxyhemo-
globin, which is irreversible, thereby, rendering hemoglobin useless as a
carrier of oxygen to the body organs and creating a condition known as
tissue oxygen hunger. In addition carbon monoxide has a depressing effect
on tissue respiration and on oxidation processes of the organism. The
basic symptoms of carbon monoxide poisoning are headache, vertigo,
nausea, vomiting and, in more severe cases, dyspnea, loss of conscious -
ness and spastic seizures. Many authors believe that chronic carbon
monoxide poisoning may develop as the result of frequent inhalation of low
carbon monoxide doses over a long period of time. Such cases are gener-
ally characterized by disturbed neuro and cardio-vascular functions. The
maximal allowable carbon monoxide concentration in the air has been
temporarily adopted as 0.02 mg/li, according to N. 101-54.J-/ Most methods
for the determination of carbon monoxide in the air are based on the reduc-
ing properties of this gas. Therefore, all or most of the substances which
change color upon reduction can be used for the determination of CO. It
must be remembered, however, that the air may contain reducing compo-
nents other than CO in the presence of which the reaction becomes non-
specific for CO. This is easily eliminated by the preliminary passing of
the tested air through a solution containing a -reagent which would absorb
I/ All limits of allowable concentrations of different toxic substances in
the air cited in the following pages have been approved by the Chief Govern-
ment Sanitary Inspector of the USSR, as specified in No. 279-59, with the
exception of some poisonous substances for which limits of allowable con-
centrations in the air have been adopted by other divisions of the sanitary
inspector.
-8-
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and thereby remove the interfering substances. The above mentioned
method for the quantitative determination for carbon monoxide in the air
can be used only in instances in which the intensity of the developing indi-
cator color varied directly with the concentration of the CO in the air,
which means that the reaction between the indicator and the CO follows a
proportional curve. Where the percentage of CO in the air is low, use
must be made of an indicator which changes color intensely, so that final
results may be estimated with a higher degree of accuracy. This, of
course, means that the reaction between the indicator and the CO must be
of a high degree of sensitivity. Below are described some methods for
the rapid determination of carbon monoxide in the air by means of filter
paper indicators enclosed inside, indicator tubes.
Qualitative Reactions
All methods described under tkis heading are intended primarily for
the qualitative determination of CO in the air, and in extreme cases only
for approximate quantitative determinations. As a preliminary step for
such approximate quantitative determination of CO in the air, strips of the
indicator paper are placed into containers filled with air having known CO
concentrations. The intensity of color change acquired by the paper and
the time in which such changes occurred are carefully noted for future
comparative purposes.
Carbon Monoxide Determination with Filter Paper Saturated
•with a Solution of Palladium Chloride in Sodium Acetate
The chemical division of the South-English Gas Company proposed a
method the principle of which is based on the reduction of palladium chloride
by carbon monoxide to its metallic state according to the following reaction:
PdCl24-CO-Pd+COCl2;
COCi3+HjO-~C02+2HCI.
In the course of the above reaction a certain amount of HC1 is formed
which acts as an interfering agent; such interference can be eliminated by
saturating the paper with a solution of sodium acetate which results in the
following reaction:
HClrCHaCOOXa-KaCI-f-CH^COOH.
In the presence of CO in the air at approximate 0. 6 mg/li concentra-
tions the indicator paper acquires a grayish color in two or three minutes.
In the presence of CO in concentration of 9 mg/li the change in color appears
-9-
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almost instantaneously. This, of course, reflects an inadequate sensi-
tivity on the part of the indicator and lack of sensitivity of the-method; the
reaction is also nonspecific, since other reducing substances, such for
instance, as hydrogen sulfide, produce a similar color change in the indi-
cator. The method can be used only where the CO concentration in the air
is high.
Reagents. 1. Palladium chloride, 1% solution. 2. Sodium acetate,
5% solution. 3. Filter paper.
Preparation pf the indicator paper. Cut the filter paper into strips of
approximately equal width, saturate with the palladium chloride solution
and dry in air free from reducing substances. Store the indicator paper in
dark glass containers.
Analytical procedure. Before beginning the analysis, moisten the indi-
cator paper in the sodium acetate solution, allow excess to drip down, and
expose the indicator paper to the air under investigation..
Determination of Carbon Monoxide in the Air
with Palladium Chloride and Agar-Agar
F. U. Rachinskii presents data of American authors who recommend
that the filter paper be saturated with a solution containing one part of
agar-agar in fifty parts of a saturated calcium chloride solution to which
palladium chloride in solution is added to make a 0.5% palladium chloride
solution.
Reagents. 1. Agar-agar, pure. 2. Calcium chloride, saturated
solution. 3. Palladium chloride, CP.
Analytical procedure. Expose the paper to the air in which the pres-
ence of CO is suspected; development of a gray color in the paper is a
positive indication that CO was present in the. air.
Modified Palladium Chloride Method for the
Determination of CO in the Air
Reagents. 1. Palladium chloride or a complex sodium-chloro-palladin-
ate salt. 2. Hydrochloric acid of sp. gr. 1.19. 3. Sodium acetate, 5%
solution. 4. Reagent - prepare the reagent as follows: dissolve Pd CL/3 ,
or Na2 (Pd CL) in a small volume of strong HC1 and dilute with water to
make a 10% palladium salt solution. Saturate the filter paper with this
reagent, dry, and store in dark containers. Before using the indicator
paper for analytical purposes moisten it with a solution of sodium acetate
and dry again in air free from reducing agents.
-10-
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Analytical procedure. Suspend the paper from a stopper in a glass
container of 1. 5 -2.0 li capacity, partly filled with water. The stopper
should have two perforations, one for air inflow, the other for air outflow.
Insert glass tubes through the stopper holes, one tc come close to the
bottom of the bottle without touching it, the other to have its lower opening
above the water surface. The air to be examined is passed first through
aspirators, one containing a solution of lead acetate, another containing a
mixture of concentrated sulfuric and nitric acids, and a third containing a
KOH solution overlaid with paraffin oil for the removal of H3S, ammonia
and aromatic hydrocarbons. The air thus purified should contain only CO
which will reduce the palladium reagent and turn the indicator paper gray
or black, depending upon the concentration of the CO in the air.
Carbon Monoxide Determination
with Palladium Chloride in Aretone Medium
The chemical reaction in this case is the same as previously described.
In 1938 Zeaflet proposed a method for the preparation of indicator paper for
the determination of carbon monoxide in the air.
Reagents. 1. Palladium chloride, analytically pure. 2. Acetone,
pure, redistilled.
Prepare_th_e_ indicator p_ap_er_as follows: dissolve 0.1 g of pure palladium
chloride in 20 ml of water and boil for 5 minutes; filter, cool and add 20 ml
of water and 20 ml of acetone; mix and store in an orange colored glass con-
tainer. The solution can be used for the purpose under consideration as
long as it remains clear. When a turbidity appears the solution is to be
discarded. Dip the filter paper into this solution for one minute immedi-
ately before use; allow excess of liquid to run off, and perform the air
analysis at once.
Analytical procedure. Place the filter paper in the air suspected to
contain CO. Development of a gray or dark color is positive indication of
CO presence in the air.
Quantitative Determination
Rapid quantitative CO determination in the air is based on the use of
solid absorbents saturated with different types of chemical reagents; glass
tubes are filled with the solid absorbent forming, so-called, tube-type
indicators. The tested air is forced through the indicator tube causing the
absorber reagent to change color, the intensity of which differs in propor-
tion to the CO concentration in the air. Experience indicated that silicagel
was the most suitable sorbent material for use in such tests.
-11-
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CO Determination, by Palladium Chloride
Gvizdala and Grych developed a rapid method in which silicagel satu-
rated with a solution of palladium chloride changed color in the presence
of CO from light gray to black. The chemical reaction is one of PdClg
reduction to its metallic state, and of consequent color change.
Reagents. 1. Crystalline palladium chloride. 2. C.P. sodium
sulphite, dehydrated. 3. Sodium phosphate, double substituted, analytical.
4. Hydrochloric acid, 4% solution. 5. Silicagel, granular, 0.1-0.2 mm in
diameter. 6. Ethyl alcohol, 96%.
Prej3a_r_aj;ion _qf_the_indicator gowde r_and the_t_ube_s_. Prepare the indi-
cator as follows: dissolve 1 g of palladium chloride .in a small amount of
distilled water; heat to 40°, and add 1 ml of NaaSOs, 1 drop at a time, until
a precipitate is formed; wash repeatedly and carefully with diluted ethyl
alcohol; decant the wash water and suspend the precipitate in 50 ml of dis-
tilled water containing 1 ml of 0.1 N solution of NaaHPO4; the precipitate
should dissolve in this solution. Pour this solution into a porcelain dish
and add 100 g of silicagel previously washed with a 4% solution of hydro-
cloric acid and dried at 90°. The granules should range between 0.1-0.2
mm in diameter. Evaporate the mixture thus obtained at 60° and place into
glass tubes; seal the tubes hermetically at both ends. By means of this
reagent CO can be detected in the air in 0. 2 mg/li concentration. Change
of color occurs within 1-2 minutes.
Apparatuses and dishes. 1. 3 250 ml beakers. 2. 2 300 ml porcelain
dishes. 3. A drying hood. 4. Color-free glass tubes of 2-3 mm inside
diameter.
Analytical procedure and calculation of results. See page 11.
Carbon Monoxide Determination by Palladium Sulfate
L.A. Mokhov and A. V. Demidov presented a modified method for the
rapid quantitative determination of CO in the air in 1957. They found that
the most sensitive color reaction with CO was yielded by palladium sulfate,
which was reduced to metallic palladium according to the following reaction:
PdS04+CO-i-H20-»H2'S04+CO2-<-Pd.
The quantity of metallic Pd thus formed varied directly with the CO con-
centration in the air, thereby imparting to the indicator different color
intensities which are used for the final quantitative determination of the
CO concentration in the air. The sensitivity of the color reactions of this
indicator can be enhanced by the addition of ammonium sulphate. The rate
-12-
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of the reaction can be accelerated by the addition of ammonium molybdate
is described below. Silicagel is used as the carrier.
Reagents. 1. Pd sulphate, crystalline, c.p. 2. Ammonium molyb-
date, crystalline, c.p. 3. Ammonium'sulphate, c.p. 4. Liquid glass,
technical. 5. Sulphuric acid, concentrated, c.p. 6. Hopcalite.
7. Dimethylglyoxime, c.p. 8. Hydrocloric acid, concentrated, c.p.
9. Ethyl alcohol.
Preparation of the silicagel. Dissolve liquid glass with distilled water
to sp. gr. of"I. 25-1. 27; dilute with an equal volume of distilled water and
mix. Take 1 li of 5. 5 N of HgSO^ sp. gr. 1.195, and add gradually, with con-
tinuous mixing, 1 li of the dissolved liquid glass. Add the liquid glass to the
HSSO4 gradually while mixing, never in the reverse order. Leave this
mixture stand at room temperature for 24 hours, in the course of which a
gelatinous mass will form which can be easily diluted whenever required.
Cut the gelatinous mass into small cubes and dry at 90° in a drying oven for
3 hours. Place the dried material into a glass beaker and cover with nitric
acid of 1. 29-1. 30 sp. gr. and leave rest for 24 hours. Wash with large
volumes of water'until the acid reaction is neutralized, as indicated by congo
red. Wash with distilled water to complete disappearance of the chlorine ion.
Place into a drying hood until the silicagel becomes thoroughly dehydrated
and comminute and sift through a screen of 0.2-0.3 mm gauge. Dry in a
muffle furnace at 600° for 8 hours.
Preparation of the indicator. Place 3 ml of 4. 8% of ammonium rnolyb-
date, 0.05 ml of 1% ammonium sulphate, and 1 ml of the palladium sulphate
solution into a 50 ml volumetric flask. The final concentration of the pal-
ladium sulphate should be 0. 019 g/ml, on the basis of palladium metal, as
determined by the procedure of Hillebrand and Landel. Acidify the solution
with hydrochloric acid of 1.18 sp.gr. by adding it at the rate of 2-3 volume
percent; to a given volume of the PdSO4 solution add 1% solution of dimethyl-
glyoxime dissolved in 95% of alcohol, at a rate at which 10 ml of the palladium
solution would require 25 mg of dry dimethylglyoxime. Leave stand for one
hour and filter through a weighed Gooch crucible. Wash the filtered precipi-
tate first with cold and then with hot water, dry and weigh. Multiply the
weight of the precipitate by coefficient 0.3167. The concentrations recom-
mended must be scrupulously adhered to; in the presence of excess indicator
the transition from one color shade to another may not be as clear-cut, and
at lower concentrations the sensitivity of the reagent may suffer.
After having prepared the mixture as indicated, add 1 g of the com-
minuted silicagel, the grains of which range in diameter between 0.25 and
0. 35 mm to the glass flask; close the flask with a tightly fitting stopper
through which a capilliary tube is passed to allow gradual entrance of the
air. Pass the air stream entering the glass fask first through a tube
-13-
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containing hopcalite, silicagel and activated charcoal, then aspirate the
purified air through the flask at a negative atmospheric pressure of 5-7 mm
of mercury for 5-6 hours, then place the glass flask into a wate rbath at
40-45° keeping the air in the glass flask at reduced pressure of 17-20 mm
of mercury. The supernatant water is then evaporated and the atmospheric
pressure further reduced to 4-5 mm of mercury until a dry yellowish
powder residue is formed at the bottom of the flask. Gradually bring the
atmospheric pressure to normal. Place the dry residue into a tightly
sealed flask in an atmosphere completely free from CO and from other
foreign admixtures.
Preparation of the indicator tube. The indicator tube should be 100-110
mm long having an inside diameter of 2-3 mm. Draw out one end of the
tube to a point as shown in Figure 7. Slight constrictions are made at either
end of the tube as illustrated. Fill the tube with the indicator material from
tVip sealed and drawn out end towards
Figure 7 the open end in the following order:
place a cotton plug at the sealed end of
the tube> overla^il wlth 5 mm of
silicagel saturated with copper sul-
phate for the absorbtion of hydrogen
FIE. 7, IHBICATOR TU«C FOR CO BETE™iNATion. sulfide. Overlay this by a small
cotton plug to keep the filled material
I. CONSTRICTION. 2. COTTON PLUS. , ,. • • <-• i
3. SitiCA«Ei. 4. INJICATOR. ln the tube ln a flxed position. Seal
5. CuS04 SATURATE9 siLiCAfiei.. hermetically and anneal at both ends,
after it has been thoroughly vacuumized.
Apparatuses:
1. Two chemical glass beakers of 3 li capacity.
2. Klaizen flask, 5 ml.
3. Pressure gauge.
4. Vacuum pump, Kamov.
5. Pipettes, 1 and 5 ml.
6. Waterbath.
7. Electric hot plate.
8. A set of sieves.
9. Bunsen funnel with an adapter.
10. Glass tubes of 2 or 3 mrn inside diameter.
Analytical procedure. Prepare the standard color scale to be used in
connection with the quantitative CO determination in the air as follows:
prepare air mixtures with known CO concentrations. The stock CO con-
centration should be 1 mg/li. Dilute this mixture with pure air so as to
obtain air with CO concentration as indicated in Table 1.
-14-
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Pass each air mixture beginning with the highest down to the lowest
successively for one minute, or until 300 ml of air has been passed,
through individual indicator tubes filled with the indicator material as pre-
viously described. The volume of passed air should be correctly estab-
lished by appropriate
Table 1 means. Allow'trie tubes
to rest two minutes for
RAREFACTIONS i
Ma/Ii OF
CO
1,0
0,7
h I.I
0,6
0.5
0,4
0,3
0,2
0,05 0,025 0.012
ij I n complete color develop-
ment, then have a color
0,005 artist reproduce the tints
developed in the indicator
tubes on a white, paper .
using appropriate water
colors, thus making a color scale representing the eleven CO concentra-
tions indicated in the above Table. Mark each color tint showing the
corresponding CO concentration. Insert the color scale into a clear glass
tube, seal it at both ends and keep protected from sunshine to prevent
color fading. In making actual determinations pass the tested air through.
the filled indicator tube in a similar manner and compare the resulting
tint with the color scale prepared as previously described. Since each of
the strips on the color scale is accompanied by a. notation indicating the
corresponding CO concentration in mg/li, the CO concentration, found in
the air can be recorded directly without additional-computation.
A similar analytical procedure can be used in establishing concentra-
tions of air pollutants other than CO. The described method enables one
to determine CO concentrations ranging from 0.005 to 1.0 mg/li by passing
100-300 ml of air through the indicator tube.
Carbon Monoxide Determination by p-Sulfanilaminobenzoic
Acid and Silver Nitrate
In 1956 A.D. Petrov proposed a method for the rapid deter ml nation of
CO in the air based on the fact that p-sulfanilaminobenzoic acid in the
presence of silver nitrate reacted with CO precipitating the silver as a
stable yellow sol which turned brown.
Reagents. 1. p-sulfanilaminobenzoic acid, c.p. 2. Silver nitrate,
crystalline, c.p. 3. Sodium hydroxide, c.p. 4, Ag - p-sulfanilamino
benzoate - prepared as follows: take two parts of 0.1 M solution of AgNO3;
add two parts of 0.1 M solution of the sodium sulfanilaminobenzoate and
one part of 1 M solution of NaOH, or in ratios of 1:1:0. 5.
Apparatus. Two Zaitsev absorbers.
Analytical procedure. Mix 30 ml of 0.1 M solution of AgNO3 with. 30 ml
of 0.1 M solution of the para-Na-sulfanilaminobenzoate and 15 ml of 1 M
-15.- ,
-------
solution of the NaOH. Use two Zaitzev absorbers; place into each 5 ml of
the prepared solution. Connect the absorbers to an aspirator and aspirate
20 li of the tested air. Determine amount of CO by comparing the color
in the absorber with a series of standard colorimetric tubes, or with the
aid of a special standard curve. Prepare the standard colorimetric scale
by passing 20 li of previously purified air containing known concentrations
of CO, as shown in Table 1; comparison is made photocolorimetrically.
Calculation of results. Compute CO concentration using the following
formula.
c=-
n-V
in which C - represents the CO concentration in mg/li;
n - represents mg of CO in the experimental tube as
determined by using the graph;
V - represents ml of the liquid contained in the absorbers;
Vj - represents ml of the liquid taken from the absorber;
W - represents li of air aspirated through the abosrber and
adjusted to normal temperature and pressure.
The reaction sensitivity is 0.0012 mg/li. The method is specific. The
only possible interference with the determination may occur in the presence
of Cl in the air.
NITROGEN OXIDES
Nitrogen oxides usually exist as a mixture of N3O,NO, N2O3, NO2,
N2 O4 and N2 Os. Nitrogen monoxide or N2 O is a colorless gas having a
somewhat pleasant odor; it is easily condensed into a liquid at 35.4° and
75 mm pressure. It acts as an oxidizer at higher temperatures due to its
decomposition into N and O2> Nitrogen monoxide does not react with nitric
oxide. Nitric oxide (NO) is a colorless gas which can be condensed into a
colorless liquid at normal pressure and -151.4°; the sp.gr. of liquid nitric
oxide is 1.039; at 164° it turns into a snow-white solid mass. Nitric oxide
easily reacts: with air oxygen which converts it to nitrogen dioxide, accord-
ing to the following formula:
Nitrogen trioxide (N3O3) is a brownish-red gas which condenses into a
bluish liquid -upon cooling and begins to decompose at -2°. Nitrogen
trioxide is chemically unstable; it is no sooner formed than it begins to
- -16-
-------
decompose into nitrogen dioxide and nitrogen oxide, which in turn may
again form nitrogen trioxide, etc.
Nitrogen dioxide (NOg) is a reddish brown gas having an unpleasant
odor. It is easily condensed into a yellowish liquid having a b. p. of +21. 3°;
it solidifies into a colorless crystalline mass having a m. p. of -9. 3°. The
density of the nitrogen dioxide molecule indicates that it is in the form of
N2O4. This compound, known as nitrogen tetr oxide, is in fact a double
molecule of NO2> At higher temperatures NSO4 begins to dissociate into
NO2 according to the formula:
N204 ^ 2N02.
It acts as a strong oxidizer and has a m. w. of 46.008. One ml of the gas
at O° and 760 mm mercury weighs 2. 053 mg; the density of NO is 1, 58
times that of air. In combination with many organic vapors NOg forms a
highly explosive mixture. This must be taken into consideration in analyz-
ing gas mixtures containing NO2> In an atmosphere of steam NO gives
rise to nitric and nitrous acids according to the following formula:
2NO2+H2O-*HN02-rHNO3.
A mixture of nitrogen oxides at normal temperature appears as a
yellowish brown vapor the color of which diminishes with increase in the
temperature. The limit of allowable concentration of nitrogen oxide in the
air computed on the basis of N3Og is 0.005 mg/li. Nearly all colorirnetric
methods for the determination of nitrogen oxides are based on the property
of oxides of nitrogen to form diazo compounds in the presence of aromatic
amines; followed by a union between the formed diazonium salt with.
another salt of the benzoic acid order or with naphthols, etc. Atmospheric
air most frequently contains nitrogen dioxide and nitrogen tetroxide. At
normal temperatures both oxides are present in the air in ratios varying
with the temperature; as the temperature rises the concentration of NO3
increases, and vice versa, as the temperature falls the N2O4 concentration
increases.
Toxicology
Oxides of nitrogen in the air consist predominantly of NOa and its
polymer N O4; either of these gases or their combinations may be the cause
of grave poisoning. Oxides of nitrogen have a strong irritating effect on
the pulmonary passages; they are less irritating to the upper respiratory
tract. Oxides of nitrogen easily permeate through the mucous membranes
-17-
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into the organism causing general poisoning. Upon entering the blood circu-
lation oxides of nitrogen combine with the hemoglobin to form methemo-
globin. Inhalation of oxide of nitrogen at first causes only a slight irrita-
tion of the respiratory passages. Later this effect becomes more general
and results in dilatation of the blood vessels and a drop in blood pressure;
nitrogen oxides act as narcotics in relation to the nerve system, elicit
degenerative changes in heart muscles, and, as stated above, upon enter-
ing the blood system produce methemoglobin. It must be borne in mind
that in nitrogen oxide poisoning there is usually an early initial period of
acute poisoning, as mentioned above, which may last for 3 to 6 hours; this
is. followed by an occult period during which the poisoning effect may
become enhanced without external evidence. This is of great significance
to the evaluation of the condition of persons who had been subjected to
nitrogen oxide poisoning. The following are outlines of some of the methods
proposed for the detection and determination of oxides of nitrogen in the air.
Quantitative Reactions
Determination of Oxides of Nitrogen with the
Aid of lodo-starch Paper
lodo-starch paper turns blue in an atmosphere of nitroge-n oxide's. The
reaction between nitrogen monoxide, nitrogen dioxide and potassium iodide
proceeds as follows: oxides of nitrogen in solution act as transmitters of
oxygen according to the following set of reactions:
NO-f-O-'NOj;
HjO-»HS]O2 +
2HNOa+2KJ-*2KOH+Ia+2NQ.
In the presence of starch the free iodine produces a blue color.
Reagents. L. Soluble starch powder. 2. Potassium iodide, crystal-
line, c.p.
Prepare the starch-iodine paper as follows: dissolve 10 g of the starch
in a small volume of cold water, gradually add the starch solution to 1, 000 .
ml of boiling water with constant stirring; boil and mix for several minutes.
Cool to room, temperature. Add to this solution 2 g of potassium iodide
previously dissolved in 15-20 ml of water. Saturate ash-free filter paper
with this final solution and dry in a darkened chamber filled with clean air.
Store the paper in dark glass containers equipped with ground-to-fit
stoppers.
-18-
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Analytical procedure. Place the starch-iodine saturated paper where
the air is to be tested. If the paper turns blue it must be concluded that
oxides of nitrogen are present in the air.
Determination of Nitrogen Oxides in the Air
with Indicator Paper
I. M. Korenman .proposed a method by which strips of filter paper are
saturated with Griess -Ilosvay solution. In the presence of nitrogen oxides
in the air the paper will turn red.
Reagents. The same as shown on the following page. The reaction -
mechanism is described below.
Analytical procedure. Place the paper where the air is to be analyzed;
in the presence of oxides of nitrogen the paper will turn rose or red.
Quantitative Determination Methods
Determination of Nitrogen Oxides by the
Indicator Tube Method
M.G. Lukina described a method for the rapid determination of NO2
based on the principle of rose-color development as a result of reaction
between NO0 and a mixture of sulfanilic acid and alpha-naphthylamine;
o
silicagel is used as a carrier agent. Intensity of the developed color is
directly proportional to the NOS concentration in the air. The silicagel is
first heat-dried and then saturated with the Griess-Ilosvay reagent. Place
desiccated material into a glass tube, as described in one of the preceding
pages, and run the air through the tube in a given volume. The reaction
proceeds as f ollows :
SOaH
.QH.-f NaN03+CH3COOH•
.NH, ' .
SOjNa'
N = N
SOaNa"
C,H4
\
NsN
+ •
• CHjCOCr+2HjO;
SO,Na
CH,COO-+C10H,NH,-»Cl>H4-N=N-C10HaNH,+
.-fCHjCOOH.
-19-
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Reagents. 1. Sulfanilic acid, c.p. 2. Alpha-naphthylamine, c.p.
3. Acetic acid, 10% solution. 4. Silicagel granules, 0.25-0.35 mm in
diameter. 5. Fuchsin. 6. Methyl violet. ,
Prepare two solutions
as follows: 1) Dissolve 0. 5 g of sulfanilic acid in 150 ml of 10% acetic
acid. 2) Dissolve 0. 1 g of alpha-naphthylamine in 20 ml of water, heat-
ing the solution in a waterbath. Decant the colorless supernatant fluid
and dissolve the precipitate in 10% solution of acetic acid to a final volume
of 150 ml.
f _the_indicato_r_ppwd_e_r. " To 10 g of "granular silicagel of"
0. 25-0. 35 mm in diameter add 5-6 ml of the Griess -Ilosvay agent pre-
pared as above indicated.
Apparatus and dishes.
1, Glass tubes 120 mm long of 6 mm inside diameter.
2. Two porcelain dishes 70 mm diameter.
3. Two 250 mm cylinder graduates.
4. Twenty and 25 ml pipettes divided into 0.1 ml. .
5. Chemical funnel. of 50 rnm diameter.
6. Glass wool. .
7. Waterbath.
Analytical procedure. Make quantitative determination by comparing
the developed color intensity with a. standard color scale, prepared in the
form of a series of tubes containing silicagel saturated with solutions of
fuchsin and methyl violet in known proportions. Final results should be
checked by the Griess -Ilosvay reaction colorimetrically and comparing
color intensity as previously described. The method sensitivity is
0.002 mg/li. Compute results as previously described.
Determination of Nitrogen Oxides
by the Ortho-tolidine Chlprhydrate Method
Kobajshi and Kitahawa proposed a method for the determination of low
nitrogen dioxide concentrations in liquid oxygen, which can also be used for
the determination of NO3 in the air. Fill the indicator tubes with silicagel
saturated with ortho-tolidine chlorhydrate. In the presence of NO3 the
indicator color will change from silver-gray to greenish-yellow.
Reagents. 1. Ortho-tolidine chlorhydrate, c.p. 2. Silicagel purified
granules of 0.2-0.25 mm diameter.
Apparatus. A portable aspirator, such as shown on page 6, Fig. 2.
-20-
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Analytical procedure. Aspirate a known volume of the air through the
si lie age I-filled tube until the indicator changed to a yellowish-green color.
The quantitative determination of NOa in the air is based on the. air volume
required to aspirate through the indicator tube for the production of the
yellowish -green color.
Calculation. Results of analysis are read on a curve constructed by
plotting NO3 concentrations along the abscissa and the volume of air along
the ordinate. Temperature of the air must be taken into consideration.
By this method NOa concentrations in the air as low as 0. 01-08 mg/li can
be detected. This is of considerable importance, since the presence of
NO2 in the air above certain concentrations may result in explosions;
Determination of Nitrogen Oxides by the
B-Naph.th.ol and Benzid'ne-Hydrochloride Method
L.A. Vtokhov and V.S. Khalturin proposed a method for the determina-
tion of oxides of nitrogen in the air with a high degree of precision. The
method is based on the fact that d-iazotization of benzene hydrochloride by
oxides of nitrogen in the presence of beta-naphthol and nickel chloride
imparted to the silicagel indicator a cherry-red color.
The sensitivity of the method is 0.0005 mg/li of NO3.
Reagents. 1. Benzidine-hydrochloride, c.p. 2. Beta-naphthol, c. p.
3. Nickel chloride, c.p. 4. Silicagel granules, 0.25-0.35 mm in
diameter. 5. Ethyl alcohol 96°.
?jepa-ra-ti_on_ of Jhe_si_licagel_indic_ajtpr. Place 0. 5 g of granulated
silicagel into a porcelain dish. Add 0.2 nil of saturated alcoholic solution
of "benzidine-hydrochloride and mix thoroughly. Add 0.1 ml of 5% alco-
holic solution of beta-naphthol and 0.1 ml of 0. 1% of nickel chloride solu-
tion and mix; desiccate the silicagel at room temperature until it acquires
a white color; pour the dry silicagel granules into 100 mm glass tube of
3 mm diameter. The height of the silicagel indicator column should be
3 mm. Superimpose by 3 mm layers of finely powdered plain silicagel;
pack in cotton plugs at each end of the silicagel, and seal the indicator
tube her rne tic ally.
Dishes.
1. Glass tubes, 100 mm long, 3 mm inside diameter.
2. Porcelain dishes, 50 mm in diameter.
3. Glass rod.
Analytical procedure. Open the sealed silicagel containing indicator
-21-
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tube at both ends, and aspirate 100 ml of air in the course of 30 sec. One
minute later compare the developed color with the colors of the standard
scale prepared by passing through a series of indicator tubes 100 ml of air
of a known range of NO3 concentrations. Depending upon the NO2 concen-
trations in the air, the developed indicator color may range from light
rose to cherry-red. The reaction is specific; the presence of ozone,
hydrogen sulphide, ammonia, carbon bisulfide, HC1 vapor, do not inter-
fere with the reaction.
Calculation of results. See Analytical procedure.
Determination of'Nitrogen Dioxide by the Line-ar'-Golorimetric
Method with the Aid of Diphenylamine and Sodium Chloride
E. D. Filyanskaya described a linear colorimetric method for the
determination of nitrogen dioxides in which she used silicagel saturated
with an alcoholic mixture of diphenylamine and acqueous solution of sodium
chloride as the sorbent indicator. The dry indicator is placed into a glass
tube as previously described for other similar methods. NO2 concentra-
tion in the air is proportional to the length of the colored silicagel layer in
the glass tube. A table of concentrations or a standard graph in the form
of a curve (.nomogram) can be prepared by aspirating through a series of
indicator-containing tubes equal volumes of air containing different NO3
concentrations and recording the corresponding lengths of the colored
silicagel layers. Precision of the method is ±10% of the length of the
colored indicator. . .
Reagents. 1. Granulated pure silicagel granules 0.25-0.35 mm in
diameter. 2. Ethyl alcohol 96°, redistilled. 3. Diphenylamine, des-
iccated, c. p.
Preparation of the powdered indicator. To 1 g of purified silicagel
granules of 0. 16-0. 32 mm diameter add 1. 2 ml of distilled water; mix
thoroughly; dry at 90-100° until the silicagel granules begin to adhere
together. In this state the silicagel will contain 38-40% of moisture.
Prepare a solution containing one part of distilled water, one part of
alcohol and three parts of 0.5% solution of diphenylamine. Add 0.2 ml
of this solution for each 1 g of silicagel, mix thoroughly and dry until
granules become free-flowing. Place the final product into glass tubes
as previously described and heat-seal at both ends.
Apparatus and dishes.
1. An aspirator consisting of two 2 li volumetric flasks.
2. Glass tubes 70-80 mm long and 3 mm inside diameter.
-22-
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Analytical procedure. Aspirate 500 ml of the air through the tubes
at the rate of 20 ml/min.
Calculation of results. Leave the tubes rest for 15 min. then measure
the length of the colored indicator layer and obtain final results by using
a standard curve prepared at the time of making the test, since the char-
acter of the curve varies with certain undetermined environmental factors
existing at the time of making the test, or at the time of the indicator
reagent preparation. In this curve concentrations are marked on the
abscissa and corresponding lengths of the colored indicator in mm are
marked on the ordinate.
Oxides of Nitrogen Determination by the Rivanol Method
V. P. Fedotov developed a. rapid method for the determination of NO3
based on the formation of a colored compound resulting from the reaction
between NO2 and 2-Ethoxy-6, 9-diamino acridine lactate, commonly known
as rivanol. The reaction proceeds as outlined below, indicating that the
amino groups of this compound become diazotized and acquire a color.
ranging from pink-rose to cherry-red, as shown below.
NH,
/ \X\XS_ 0_QH6
H,N-
N
DlAMINOACRIDIN LACTATE
NH3
H3N-
CHjCHOH • COOH
N
OlAMIIJOACRIOIN LACTATE
CHOH
coo-
NHj
H N-
N
CH,
I H-0'|
OlAMINOACRIOIN LACTATE
NH,
/*.
- O - C3H»
i
,N
COO" |Oi
NITRIC ACID
N '
CH3
• CHOH + 2HaO
COO"
C01.CBEO PRODUCT OF DIAZOTIZED RIVANOL CONSTITUTING A SALT OF
COMPLEX CHEMICAL STRUCTURE.
-23-
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Reagents. 1. A 10% solution of 2-ethoxy-6, 9-diamiho acridine lactate,
or rivanol. 2. Potassium.bisulfate, crystalline. 3. Silicagel, granular,
0. 25-0. 32 ml in diameter.
Preparation of-the silicagel indicator and .of the tubes. Saturate the
silicagel with the solution of rivanol and potassium bisulfate; thoroughly
dry the silicagel and place into glass tubes 60 mrn long and 5 mm in
diameter as described in some of the preceding paragraphs.
Apparatus and dishes. '
1. Anr-asprrator consis-ting of two-3-li volumetric flasks. . - ••
2. Glass tubes 50-60 mm long and 2 mm in diameter.
Analytical procedure. Aspirate 1-2 li of the air through the tubes at
a rate of 3-6 li/min.
Calculation of results. Quantitative determination is made by compar-
ing the color intensity imparted to the material in the indicator tubes by
the aspirated air with the color intensities of a standard scale, such as
was previously described. The reaction sensitivity permits the determina-
tion of NO within the range of 0. 004 and 0.1 mg/li.
HYDROGEN PEROXIDE (HSO2)
Pure H Oa is a thick colorless fluid which has a specific gravity of
1. 465 at O° and a low pH. Its m. p. is + 0. 89°, b. p. 80. 2° at 47 mm of
mercury. It easily breaks up into water (H3O) and oxygen (Os); it is more
stable in dilution. Hydrogen peroxide is a strong oxidizing agent. In
direct contact with the skin H3O3 causes skin burns and skin itching accom-
panied by a bleaching effect. Soon after washing away of the H2O3 the skin
returns to normal. .
Toxicology
Highly concentrated H3O3 is widely used for a variety of .purposes and
can be a source of indoor air pollution. In the gaseous form H3O2 irritates
the mucosa of the respiratory tract and of the eyes. Highly concentrated
H O2 can act as a resorptive agent when in prolonged contact with the
organism, therefore, early detection of high H3O3 concentration in the air
is essential in preventing undesirable consequences. No limit of maximal
concentration lias been established for H3O3 in the air at this time.
-24-
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Qualitative Reactions
Determination of Hydrogen Peroxide by a Photographic Plate
Reagents . 1. Sodium thiosulfate, 20% solution. 2. Potassium ferri-
cyanide, 0. 8% solution. 3. Feric chloride, . 0. 4% solution.
Analytical procedure. I.L. Roikh developed the following method for
the detection of H3Oa. A photographic plate is freed of its silver bromide
by a 20% solution of sodium thiosulfate; the plate is then submerged into
an 0.8% solution of potassium ferricyanide followed by an 0.4% solution of
feric chloride for 2-3 min. The plate is then kept in the room where the
presence of a H2O2 is suspected, Development of a blue color 011 the plate
is evidence of the presence of H2O2 in the air. The intensity of the blue
color is directly proportional to the concentration of H2CX, in the air. The
reaction is represented by the following equations:
3K3H[Fe(CN)6] + 4FeCl3 -*Fe4[Fe(CN)6]3
Photographic plates prepared as above described should not be used
on the day of their preparation. Filter paper saturated by the above
mentioned solutions can be used instead of photographic plates.
Determination of Hydrogen Peroxide with Titantic Acid
Koldhoff and Sandel proposed a method for the determination of H2O3
based on the formation of a reddish-orange color as the result of reaction
between H3O3 and titantic acid (see literature index), as indicated below.
Sensitivity of the reaction is 0. 003 mg.
Determination of Hydrogen Peroxide with Titantium Sulfate
Berisso and Acino described a micro-chemical variation of the above
test in which they used a 10% solution of titantium sulfate in 6 N sulfuric
acid solution in pure amyl alcohol.
Reagents . 1. Tantium sulfate, 10% solution in 6 N sulfuric acid.
2. Amyl alcohol, redistilled.
Analytical procedure. Place 3 ml of each of the above reagents into a
test tube, mix well and allow to stand until layers become clearly separated;
place 1 ml of the alcoholic layer into another tube and add a drop of the
tested solution of H2O2, obtained by passing the tested air through an ab-
sorber filled with distilled water. In the presence of H2O2 a blue color will
appear in the test tube. The reaction proceeds as follows:
-25-
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ti(SO«)2+H2O2-H2[Ti02(SO,);].
Sensitivity of the method is 0.05 mg/ml.
Determination of Hydrogen Peroxide by the
Potassium Dichromate Method
In the presence of H3O3 potassium dichromate forms a peroxy-chromic
cid (HCrO5) which is of a deep blue color. The reaction is sensitive.
Reagents. 1. Sulfuric acid", 1:5 dilution. 2. Ethyl ethe'r, fresMy
edistilled. 3. Potassium dichromate, 5% solution.
Analytical procedure. Place 1 ml of the tested "solution into a test tube;
add a few drops of sulfuric acid, 2 ml of ether and several drops of potas-
sium dichromate. Mix well and allow the mixture to separate into layers.
In the presence of H2O2 the ether layer will turn blue. The sensitivity of
the test can be enhanced by the addition to the mixture of diphenylcarbazide
prior to the ether addition. The added reagent will react with a peroxy-
chromic acid producing a violet-red color even when no blue color has
developed in the presence of the ether alone. Sensitivity of the method is
0. 01 mg of H2Oa.
Determination of Hydrogen Peroxide by the
Guaiac Gum Resin Method
In the presence of malt distase the reaction is highly sensitive.
Addition of hydrogen peroxide to the mixture of guaiac resin and malt
distase develops a blue color.
Reagents. 1. Gum guaiac resin, 2% infusion in 96% ethyl alcohol.
2. Malt extract.
Analytical procedure. The procedure is as follows: Add the 1 or 2%
infusion of gum guaiac in 95% alcohol to the tested solution slowly until
turbidity appears. Then add several drops of the malt extract prepared at
low temperature. In the presence of H3O3 a blue color will appear sud-
denly. It is recommended that only the inside parts of gum guaiac be
used and that only a fresh alcoholic infusion be employed. The sensitivity
of the test is: 1:50,000,000.
-26-
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Quantitative Determination of Hydrogen Peroxide
Hydrogen Peroxide Determination with Phenolphthalein
The method was proposed by Luis McCabe; it is based on the oxidation
of colorless phenolphthalin to phenolphthalein in alkaline solution accom-
panied by the development of a pink to red color depending upon the con-
centration of H2Oa. Schematically the reaction can be represented as
follows:
OH OH
I -II [Si! I II
COLORLESS PHENOLPHTHALIN RED PHENOLPHTHALEIN
III ALKALINE MEDIUM IN ALKALINE MEDIUM
Reagents. 1. Phenolphthalein, c. p. 2. Granulated zinc. 3. Granu-
lated zinc. 3. Sodium hydroxide, c. p. 4. Copper sulfate, c.p.
Dishes and auxiliary materials:
1. Glass flask of 100 ml capacity.
Z. Return condenser.
3. Chemical funnel of 50 mm diameter.
4. Glass -wool.
Preparation of the phenolphthalin solution. Place 1 g of phenolphthlein
in a ToO~~mI~d~istflli~ng~ "glass "flask;" add"fO~g of NaOH, followed by 20 ml of
distilled water and 5 g of powdered zinc. Connect the distilling flask to a
return condenser and heat on an electric plate for 2-5 hrs. , or until the
liquid becomes colorless; cool, filter and dilute with distilled water to
50 ml. Add some granulated zinc. Dilute 10 ml of this solution with water
to 30 ml; place 100 ml of distilled water into a flask and add 1 ml of the
final phenolphthalin solution and 1 ml of 0. 01 CuSO4.
Preparation of the standard scale. Prepare the standard color scale
using'a solution containing o". 1 mg of H2OS for each 1 ml of water (0.01%
solution).
-27-
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?_r_e-P_a_r_e_ the _0_-_01%_splution^of_HsOs as f oll_o_ws : make a 30% stock solu-
tion of the H2O2; place 10 ml of the -stock solution into a 500 ml volumetric
flask and fill with distilled water to the 500 ml mark. Titrate with a
standard solution of permanganate according to the following reaction:
+ 8H2O + 502. :
Take 10 ml of this solution and place into a 250 ml Erlenmeyer flask,
add 50 ml of distilled water and 20 ml of 1:3 dilution of sulfuric acid and
titrate with 0. 1 N KMnO4 to a light rose color which should persist for one
minute. Compute content of H2O2 in the solution using the following formula:
which
V
K
1. 7
represents the amount of H2O2 in mg/ml of the titrated
solution.
represents ml of 0.1 N KMnO4 solution used in the titration.
represents the KMnO4 solution correction coefficient.
is the weight in mg of H2O2 equivalent to 1 ml of exactly
0.1 N KMnO4 solution.
represents ml of H2O2 solution taken for titration.
The standard solution of H2O2 (0. 1 mg of H2O2 in 1 ml of the solution)
obtained by appropriate adjustment with distilled water.
Prepare the standard colorimetric scale as indicated in Table 2.
Thoroughly mix the content of the test tubes and keep for 20~ min.
Table 2
TUSE
No.
1 1
2
3
4
5
6
7
i
He OF H202
IN 10 Ml OF
THE SOLUTION
0,005
0,010
0.0.30
0,050
0,070
0,090
0,100
Ml OF STANDARD
H202 SOLUTION
0,05
0.10
0,30
0,50
0,70
0.90
1,00
Ml OF H^g
4,95
4,90
4,70
4.50
4.30
4,10
4,00
Ml OF PHEMOL-
PHT'HALIN SOLD.
5
5
5
5
5
5
5
-28-
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Analytical procedure. Take 10 ml of the final solution and place into
an absorber; aspirate the tested air at the rate of 800 ml per min. for 10
min. Pour the absorber solution into test tubes and compare the developed
color with the colors of the standard scale.
Calculation of results. Calculate results according to the following
formula:
in which P represents the HaO2 coircertt rattan- in mg/li.
C represents mg of H2O3 in the absorber.
V represents li of aspirated air reduced to standard
temperature and pressure
OZONE (O3)
Ozone in the form of gas is of a sky-blue color, while liquid ozone is
of a dark blue color; in the solid state it turns black. Solid O3 melts at
-250° and boils at - 112. 3°. Liquid ozone may explode at a result of a
sudden impact. Ozone is soluble to the extent of 45 volumes of the gas in
100 volumes of water. Under similar conditions carbon tetrachloride ab-
sorbs only 3 volumes of the ozone. The m. \v. of ozone is 48.00; 1 ml of
ozone gas at O° and 760 mm of mercury weighs 2.Z2 mg; the specific
gravity of ozone in relation to air is 1. 71; the molecular volume of ozone is
21. 6; ozone has a specific odor even in 1:5, 000, 000 dilution.
Toxicology
Ozone irritates the mucous membrances of the nose, the eyes and
throat in 0.001 mg/li concentrations. At higher concentrations it also
irritates the respiratory passages, causes nausea, vomiting, headache,
vertigo, and a pronounced drop in cardiac activity. The limit of allowable
ozone concentration in the air was officially set at 0.0001 mg/li. Many
methods have been proposed for the determination of ozone in the air, of
which the following are the simplest and most convenient.
Quantitative Reactions
Determination of Ozone by the Starch-Iodine Paper Method
D.I. Mendeleev recommended a rapid method for the determination of
ozone in the air by the starch-iodine paper procedure which was based on
the fact that in the presence of ozone potassium iodide (Kl) liberated the
1 -Z9-
-------
iodine which turned starch-saturated paper blue. The reaction is repre-
sented by the following equation:
2KI+O3-fH2O - 2KOH +IS + O3
The method is nonspecific due to the fact that other oxidizing reagents
yield similar results.
Reagents. 1. Soluble starch. 2. Potassium iodide, crystalline, c.p.
Preparation of the indicator paper. Wash 1 g of soluble starch in cold
water; place it into an open dish and add- 6 -10- ml of distil-led water; con-
tinuously stir with a glass rod while adding gradually 50 ml of boiling water;
cool. Add to the opalescent starch solution 0. 5 g of KI and mix. Saturate
ash-free filter paper with this solution, dry in the dark, cut into strips,
and store in dark tightly stoppered bottle.
Analytical procedure. Expose the starch-iodine saturated paper strips
to the tested air. In the presence of ozone a blue color will appear.
Determination of Ozone by the Method of
Litmus Paper and Potassium Iodide
Ozone can be qualitatively detected in the absence of H2O2 by means of
litmus paper as follows: dip the litmus paper into a solution of potassium
iodide and exposed to the tested air. In the presence of ozone free I2 will
be formed which will turn the red litmus paper blue. The sensitivity of the
method is 0.001 mg.
Reagents. 1. Red litmus paper. 2. Potassium iodide, 2% solution.
Analytical procedure. Place the Kl-saturated litmus paper at the place
of air testing; in the presence of ozone the litmus paper will turn blue.
Determination of Ozone with
Manganese Chloride Saturated Paper
Reagents. 1. Manganese chloride, 5% solution. 2. Filter paper
saturated with the above solution constitutes the indicator. In the presence
of ozone in the air the paper will turn brown; no reaction will occur in the
presence of H3O2 The reaction course is represented by the following
equations:
• 2MnCl2+263+3H20-> 2HMn04 + 3HCl + HOCI.
-30-
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Analytical procedure. The same as in the case of starch-iodine filter
paper method, (see page 30)
By this method ozone can be detected in the air in concentration of
0.0015 mg/li.
Quantitative Ozone Determination
Ozone Determination by the Indigo Carmine Method
L.A. Mokhov and V. P. Dzedzichek developed a rapid method for the
quantitative determination of ozone in the presence of nitrogen oxides. The
method is based on the fact that the indigo carmine molecules split under
the influence of ozone at the double bond, as shown in the following diagram.
O
O
; NaO3S
H
BLUE COLOR
\N'—
I '
H -
2Oj-fOC<;
+OJ+H,O.
o
NaO3S —
\.
c=o
+H30,
H
COLORLESS PRODUCT OF IHDISO CARMINE OXIBATIOH.
As the indigo carmine molecule splits it loses its color, so that the degree
of color fading serves as an indicator of the ozone concentration in the air.
Reagents. 1. Indigo carmine, 0. 01% solution. 2.
10% solution. 3. Silicagel granules, 1 mm diameter.
1.84 sp.gr. 5. Chromic anhydride, c.p.
Manganese sulfate,
I. Sulfuric acid of
. ^f J]\e_indic3j:or_t_u_be. Saturate 1 g of silicagel with a
mixture of 2 ml of 0.01% solution of the indigo carmine and 1 ml of 10%
solution of manganese sulfate. Allow the mixture to dry and place into a
3 mm diameter glass tube. At either end pack in lightly glass wool to
prevent the silicagel from running out. Place over the glass wool a. layer
of silicagel saturated with a mixture of chromic anhydride and sulfuric
-31-
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acid to absorb the oxides of nitrogen where such may be present in the air.
Again insert glass wool plugs. Prepare the silicagel for the absorption
of oxides of nitrogen as follows: to 4.7 g of silicagel previously heated
to 35-38° add 2 ml of a solution of chromic anhydride in concentrated
sulfuric acid (20 ml of concentrated sulfuric acid and 0. 6 g.of chromic
anhydride).
Dishes and auxiliary materials:
1. Glass tubes 60 mm long and 3 mm inside diameter.
2. Porcelain dishes 50 mm diameter.
3. Glasrs rods.
4. 5 ml pipettes divided into 0.1 ml.
Analytical procedure. For quantitative determination compare color
intensities yielded by the test with those of a standard scale described on
pages 14 and 15 including Table 1.
Compute results as described for CO on page 15.
Ozone Determination with. OrtKotolidine
Saturated Filter Paper
V.I. Shirskaya developed a method by which ozone is determined in
the air using filter paper saturated with a solution of orthotolidine. In
the presence of high ozone concentrations in the air the paper acquires a
dark orange color and an orange to yellow color at lower ozone concen-
trations. The author offered no suggestions regarding the nature of the
reaction. Sensitivity of the method is 0. 0001 mg/li.
Reagents. Orthotolidine,- 1% alcoholic solution.
Apparatus.
1. See page 7, Fig. 5. .. .
2. Strips of paper or of crab parchment.
Preparation of the indicator paper. The crab parchment, which in
fact is paper used for wrapping se'afood in stores, is cut into narrow
strips which are saturated by soaking them for 5 minutes in a 1% alcoholic
solution of .orthotolidine.
-32-
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Analytical procedure. Use the apparatus shown in Fig. 5, page 7, but
of a smaller size. Aspirate 5 li of the studied air using any one of the
aspirators previously described at the rate of 1 li per min. Compare the
developed color with the colors of a standard scale. Compute results as
outlined on page 14. Prepare the standard color scale by passing air of
known ozone concentrations through the indicator tubes containing the
orthotolidine saturated paper. It is recommended that ordinary filter
paper, ash-free filter paper and draftsmen's paper not be used as indi-
cator paper, since they all have a tendency to develop a yellow color upon
exposure to air which renders the ultimate product less sensitive to the
ozone reaction. The shortcoming of this method is due to the fact that
the color developed as a result of reaction with ozone is not permanent. -
CHLORINE
* e£'
Chlorine is a yellowish green gas having a pungent odor which can be
felt at concentrations as low as 0.003 mg/li. The m.w. of Clg is 70.914;
its molar volume is 22. 02; its density in relation to air is 2. 49; 1 ml of C12
at O° and 760 mm of mercury weighs 3. 22 mg. Its solubility in water is
two volumes of the gas in one volume of water; such a solution is generally
known as chlorine water. Chlorine gas is less soluble in a saturated NaCl
solution; C C14 does not react with chlorine gas.
Toxicology
The gravity of chlorine intoxication depends upon its concentration in
the air and upon the duration of exposure to its effect. At 0.1-0.15 mg/li
grave symptoms of intoxication may appear after 10 to 15 minutes inhala-
tion. The following symptoms may appear: sharp irritation of the mucosa
of the respiratory tract, labored respirations, painful cough and dyspnea,
followed later by pulmonary edema.
The limit of allowable chlorine concentration was set officially at
0. 001 mg/li. The following can be recommended as a most convenient
rapid method for the determination of chlorine in the air.
Quantitative Reaction
Determination of Chlorine in the Air by the
Starch-Iodine-Paper Method
R.B. Theis and V.N. Kolycheva regard the starch-iodine-paper
method for the determination of chlorine in the air as the best because of
the easily discernible blue color. For the preparation of the paper see
page 31 in connection with ozone determination. The reaction is presented
-33-
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by the following equation:
2KI +C12 -. 2KC1 + Lj
The method is not strictly specific, since other oxidizing air compo-
nents react in the same way as chlorine.
Reagents. See page 30.
Method of analysis. See page 30.
Chlorine Determination by the Method of
Arceneous Anhydride Oxidation with Potassium Iodide
The method is based on the oxidation of arceneous anhydride by chlorine
gas in alkaline solution in the presence of potassium iodide.
Reagents. 1. Arceneous anhydride, 0.001N solution. 2. Potassium
iodide, 5% solution. 3. Potassium bycarbonate, 50% solution. 4. Soluble
starch, 20% solution.
Analytical procedure. Use a micro absorber; place into it an absorber
solution prepared by mixing one part of solution 1 with one part of solution
2 and 5 parts of solution 3 to -which add 5 drops of the starch solution.
Aspirate the air under study through the micro absorber at the rate of
0.1 li per min. for 10 min. In the presence of chlorine the color of the
micro absorber solution will turn blue.
In the opinion of the authors the test is specific even in the presence
of such oxidizing agents as bromine, ozone, oxides of nitrogen, and other
similar substances. The sensitivity of the method is 0.001 mg/li. The
authors do not explain the reaction mechanizm.
Quantitative Determination of Chlorine in the Air
The Benzidine Acetate Method •
Chlorine can be detected in the air by the method of T.N. Kozlyaeva,
I.G. Vorokhobina and V. V. Zapol'skii in concentrations ranging between
0. 005 and 0. 01 mg/li. The method is based, on the fact that in the presence
of chlo.rine in the air, paper saturated with benzidine acetate acquired a
blue color. The reaction proceeds as shown under groups of equations
a) and b).
-34-
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a) Clj+H2O
6) HOC1
HOC1 + HC1;
•HC1 + O;
B) 2
• CHjCOOH] + 0] + O -* 4CH3COOH + H20 +
Reagents. 1. Prepare benzidine acetate solution by adding one part of
the benzidine acetate saturated solution to an equal part of distilled water.
Apparatus.
1. Aspirator.
2. A device such as is schematically illustrated in Fig. 8 should be
marked at 200 ml. The neck of the bottle is closed by a tightly fitting rubber
stopper having a hole in the center through which a glass tube is inserted
bent at a right angle ending in a funnel-shaped glass apron as indicated by
mark 2 in Fig. 8. The construction of the funnel is schematically repre-
sented in Fig. 9.
Figure 8
l
v>-»
Sr
Fis. 3. DEVICE FOR AIR
ASPIRATION THROUSH INDI-
CATOR ?AfER.
I. 3CTTLE. 2. FUNNEL.
Figure 9
FIG. 9. SCHEMATIC
STRUCTURE OF
FUNNEL.
1 - is the funnel; 2 - is a 10 mm
diameter sealed-in glass tube;
3 - is a sealed-in porous glass
filter which supports the circular
indicator paper; 4 - is a tightly
fitting ebonite or rubber circular
plate with a central opening for the
passage of the glass tube; 5 - is a
combination of a two-section
standard color scale and a color-
less indicator section (see Fig. 10),
the color sections representing
0. 002 and 0. 001 mg of chlorine in
20 li of air; it is made of indicator
paper and is placed on top of the
ebonite or rubber plate 4; 6 - is a
circular glass plate which is placed
over the trisectional indicator
paper 5; 7 - is a metallic ferrule.
-35-
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The standard color scale is illustrated in Fig. 10; it consists of a
circular paper marked off into three sectors, one of which is colorless,
the color of the second represents 0.002 and of the
Figure 10 third section 0.001 mg per 20 liters of air. Pre-
pare the solution for moistening the paper as
follows: to one part of a saturated benzidine acetate
solution add two parts of distilled water. Cut out
ash-free filter paper circles of diameter equal to
that of the glass tube and saturate with the above
described solution.
Analytical procedure. Place the benzidine moistened
circular filter paper over the porous plate inside the
tube funnel with the aid of pincers. Fill the aspira-
FIG. 10. Couoa STANIARI. tor with water UP to the 20° ml mark. Allow the
200 ml of the water to run out of the aspirator in the
course of one minute by appropriately releasing
pinchcock 4 at the bottom of the aspirator flask. Compare developed color
with the standard as soon as test is completed. Convert the chlorine con-
centration into mg/li by multiplying by 5 the value obtained by comparison
with the color standard. If the final test color intensity falls between the
two standard intensity, then take the average of the two standards. The
color standards are prepared as previously described by passing known
chlorine quantities through the reagent saturated filter paper. Report re-
sults after adjusting chlorine volume to standard temperature and pressure
conditions.
Actual chlorine weight in the pipette in mg can be determined by multi-
plying the chlorine volume in the pipette by coefficient 3. 214; vacuumize a
dry bottle of 4. 3 li capacity, connect the pipette to the bottle and pass the
gas from the pipette into the bottle; using an air pipette remove 8. 32 ml of
the air from the bottle for further dilution by transferring the air into
another bottle of 11 li capacity. The final chlorine concentration will
amount to 0.005 mg/li. Aspirate the air with the known chlorine concen-
tration from the second bottle through a funnel lined with benzindine
saturated paper, and reproduce the developed color on paper in water
color.
Calculation of results. As outlined on page 15.
Chlorine Determination by Potassium Bromide
and Fluorescein Method
This method was proposed by T.N. Kozlyaeva and I.G. Vorokhovina
and is based on the fact that chlorine replaced bromine from potassium
bromide. The free bromine then combines with the fluorescein forming
tetra brom fluorescein (eosine) which is of a bright rose color.
-36-
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The reaction proceeds as follows:
2KBr-J-Cl2-2KCl
AMI FURTHER
FLUORESCEIN
+«*•
13
U IS
\i n
!«.
20
+ 4HBr
:=o
EcsiH (PJLSPSERBY REB)
(1,3,7,11-rernmcfiFt.uosESCEiN)
Reagents. 1. Fluorescein, c.p. 2. Potassium carbonate.
3. Glycerin, anhydrous. 4. Potassium bromide, c.p. 5. NaOH,
analytical. 6. Filter paper, ash-free.
Preparation of the Fluorescein Solution and of the Paper
Prepare the fluorescein solution as follows^: dissolve 0. 2 g of fluores-
cein in the smallest possible volume of 10% NaOH. Add 30 g of potassium
bromide, Z g of potassium carbonate and 10 ml of glycerine; mix to com-
plete solution. Saturate strips of filter papej with this solution and dry.
Dishes.
1. Cylinder, graduated at 50 ml.
2. Pipettes, 5 and 10 ml, one of each..
Analytical procedure. Place the saturated indicator paper at the place
of air analysis. In the presence of chlorine in the air a bright rose color
will develop, the intensity of which is proportional to the chlorine concen-
tration in the air. Quantitative determinations can also be made by this
method. For this it is necessary to prepare a standard color scale for
final determination. Sensitivity of the method is 0.001 mg/li, which is
adeauate for the determination of below toxic concentrations and within the
0.001-0.002 mg/li limits of allowable concentration.
Calculation of results. See page 15.
-37-
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Chlorine Determination by the Fluorescein Method
The Linear colorimetric method of E.D. Filyanskaya for the determina-
tion of chlorine is based on the above described formation of eosine as a
result of reaction between chlorine and fluorescein. The chemical reaction
is illustrated on the previous page. Other haloids and oxidizers interfere
with the chlorine determination.
Reagents. 1. Potassium bromide, c.p. 2. Potassium carbonate,
c.p. 3. Fluorescein, c.p. 4. Silicagel, granular, 0.'25-0.13 mm in
.diameter. 5. Potassium hydroxide, 10% solution.
Preparation of the indicator powder and of the tubes. Prepare the
indicator powder as follows: 1) dissolve 30 g of potassium bromide and 1 g
of potassium carbonate in 10 ml of distilled water; 2) dissolve 0.1 g of
fluorescein in 1 ml of 10% solution of KOH. Mix the solutions before using
and dilute with distilled water in 1:5 ratio. Moisten 1 g of the purified and
desiccated silicagel in 1. 2 ml of the fluorescein solution. Stir well with a
glass rod to complete powder color homogenation; dry at 100-105° in a dry-
ing oven, continuously stir the mixture until the powder is completely
moisture-free. Prepare the indicator tube as follows: take a glass tube of
2. 5-2. 6 mm inside diameter and 90-91 mm long. Insert a small -wad of
hygroscopic cotton of 0. 5 mm thick at one end of the tube; place over it a
60-70 mm column of the silicagel indicator. Pack it in lightly and seal the
tube at both ends with rubber caps.
Apparatus and dishes.
1. Cylinder graduates, 20 ml, 2.
2. Pipettes, 10 ml, 2.
3. Porcelain dishes 10 ml diameter, 1
4. Tubes, indicator as specified above.
5. Hood, drying.
Analytical procedure. Aspirate 300 ml of the studied air through the
indicator tube; measure the length of developed color in the tube, and
determine chlorine concentration with the aid of a standardized curve. 'The
latter is constructed as previously described for other substances.
Calculation of results. Results are recorded by measuring the length
of the color-changed silicagel columns in the indicator tube, and then
interpret in terms of chlorine concentration. The plotted functional
relationships between the length of the colored silicagel indicator layer
and the chlorine concentrations in the air assume the form of a straight
line curve. • .
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HYDROGEN CHLORIDE (HCl)
Hydrogen chloride is a colorless gas which has a pungent odor. It
appears in the form of a smoke due to the fact that it formed an aerosol with
water vapor of the air. The mol. wt. of HCl gas is 36,465; its mol. vol. is
22. 25; its density in relation to air is 1. 2679. One cm3 at O° and 760 mm
of mercury weighs 1.6391 mg. Under standard pressure and temperature
one volume of water absorbs 450 volumes of HCl gas. A solution of HCl
in water is commonly known as hydrochloric acid.
Toxicology
Hydrochloride gas irritates the mucous membrances of the nose,
throat, and eyes. At high concentration it produces a turbidity of the eye
cornea. Continuous exposure to the effect of hydrochluride gas is destruc-
tive to the teeth. The action of hydrochloride gas on the organism is
general through its capacity of disturbing many individual functions and
function systems. The limit of allowable hydrochloride gas concentration
was set officially at 0. 01 mg/li.
Qualitative Reactions
Hydrochloride Gas Determination
with Litmus Blue or Congo Red Paper
Methods for the rapid determination of hydrochloride gas are based on
indexes of filter paper saturated with litmus blue.
Reagents. Litmus, 1% solution in water slightly acidified with 0.5% of
hydrochloric acid, or 0.1% of congo red slightly alkalinized with 0.1% solu-
tion of NaOH to the point of pH-8. 0.
Analytical procedure. Place the indicator paper where the air is to be
investigated. In the presence of hydrochloride gas the blue of the litmus
paper will turn red, or the red of the congo paper will turn violet-blue. The
reaction is nonspecific: analogous changes in the paper color can be brought
about by other volatile acids.
Hydrochloride Gas Determination with Silver Nitrate
Reagents. 1. Silver nitrate, 5% solution. 2. Nitric acid, sp.gr. 1.41.
Analytical procedure. Aspirate the tested air through an absorber con-
taining 10 ml of water, then add 1 ml of the silver nitrate solution. In the
presence of high hydrochloride gas concentrations in the air a grayish
-39-.
-------
white precipitate will form, and in the .presence of low hydrochloride gas
concentrations in the air a turbidity, of different intensity vail form;
neither the heavy precipitate nor the slight turbidity will disappear upon
the addition of several drops of nitric acid, but will dissolve upon the
addition of ammonia.
Qualitative Determination Methods
Determination of Hydrochloride Gas with the Aid of Silver Nitrate
.The method described below is not of the rapid type. However, the
authors take this opportunity to describe a nephelometric method for the
determination of hydrochloride gas. Despite the fact that the time required
for the performance of this test is more consuming than of any of the rapid
tests, it possesses the advantages of technical simplicity. Another reason
for the presentation of this method is the fact that a review of the literature
failed to find an adequate method for the rapid determination, of hydrochlo-
ride gas in the air. In this connection it should be added that many indus-
trial laboratories use this method of air analysis. In making determina-
tions by this method the tested air is aspirated through distilled water.
Add silver nitrate to the formed hydrochloride solution which will produce .
a turbidity due to the formation of insoluble silver chloride according to
the. following reaction:
HC1 + AgNO3 '-« AgCl + HNO3
The intensity of the formed turbidity is directly proportional to the concen-
tration of hydrochloride in the absorber water. Make the determination.
nephelometrically by comparing the degree of turbidity in the experimental
tube with that of a standard set of tubes prepared for the purpose.
Reagents. 1. Sodium chloride, c.p. 2. Silver nitrates, c.p.
3. Nitric acid, 1% solution.
Preparation of the standard scale. Dissolve 0.1603 g of NaCl in 1 li
of water. One ml of this solution should be equivalent to 0,1 mg of HC1 gas.
The rest of the procedure is implied in. Table 3 below.
Table 3
TUBE
Mo.
1
2
3
4
5
6
•VflLiiMS Of
8TAHDARO
SOLUTION
WATER
VOLUME -
'/'HlrlS BF '
K JiK03
SOL I'll OH
VOlUM£ OF
l<$ AGMOs
SOUJTIOH
i IN Ml
0.1
0.2
0.3
0.4
0.5
0.6
7.9
7,8
7.7
7,6
7.5
7.4
1 Hi
ro
A.LL
Tims
1 Hi
.10
AIL
TL'3ES
MS Of
HCI
0.01 .
0.02
0.03
(i,04
0.05
0.06
-40-
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Dishes.
1. Petri absorbers, 2.
2. Tubes, colorimetric, 15 ml capacity, 20.
3. Flask, volumemetric, 1 li capacity, one.
4. Cylinder graduates, 25 ml capacity, 5.
5. Pipettes, graduate, 10 ml divided into O.lml, 2.
6. Pipettes, 2 ml, graduated into 0.01 ml, 2.
7. Glass rods, 2.
Analytical procedure. Place 24 ml of double distilled water into a petri
absorber and aspirate through it 5 to 15 li of the tested air at the rate~of 100 11-
per hour, the volume of air to be aspirated will depend upon the anticipated
concentration of the hydrochloride gas in the air. Upon completion of the
aspiration take 8 ml of the water from the Petri absorber and pour into a
colorimetric tube; add 1 ml of nitric acid and of silver nitrate of the above
indicated concentrations and mix thoroughly, then compare the degree of
turbidity with the standard scale.
Calculation of results. Compute final results using the following formula:
in which C represents the mg/li of hydrochloride gas in the air;
n represents the HC1 in the experimental tube as determined
by comparison with the standard scale.
V represents volume of fluid orginally contained in the Petri
absorber
Vj represents volume of fluid taken from the Petri absorber
and placed into the colorimetric tube;
W represents li of air aspirated through the absorber.
Example. Fifteen li of air was aspirated through the Petri absorber. The
absorber contained 24 ml of distilled water; 8 ml of the 24 was taken for
final analysis. Comparison with the standard scale indicated that turbidity
in colorimetric tube #5 corresponded to'0.05 mg HC1; substituting these
values into the formula shown below the following is obtained.
0.05-24 nn, /,.
- -=0,01 mg/h
o • 1O
The presence of chlorine in the air does not interfere with the analysis.
-41-
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HYDROGEN SULFIDE
Hydrogen sulfide is a colorless gas. One part of HgS in 100, 000 parts
of air can be clearly perceived by its specific odor. Mol. wt. of H2S is
34.08; density in relation to air is 0.1906; one cm3 at O° and 760 mm of
mercury weighs 1.5392 mg. Mol. vol. of HgS is 22.14. Under normal
conditions one volume of water will absorb 3 vol. of H2S resulting in the
formation of approximately 0.1 M solution. At.higher temperatures the
solubility is reduced, so that at the boiling point water can be completely
freed from H2S. One vol. of alcohol absorbs about 10 vol. of H2S.
Toxicology" - - .._-_-...,. . .-. -
Hydrogen sulfide is highly toxic, especially under chronic conditions.
Acute hydrogen sulfide intoxication produces headaches, weakness, vertigo,
nausea, irritation of the eye, nose and respiratory tract mucosa, and at high
concentration loss of consciousness and central nervous disturbance. Many
toxicologists doubt the possibility of chronic HgS intoxication. Nevertheless,
numerous reports appeared in the literature dealing with sickness due to
continuous exposure to 0.15-0.2 mg/li of HgS. Under such conditions patients
complained of burning in the eyes, conjunctival irritation, corneal damage,
lacrimation and photophobia. It may also cause disease of the upper respir-
atory tract, such as bronchitis. Symptoms may appear of digestive system
disturbance, anemia, vertigo and dermatitis. The morphological blood
picture may change profoundly. The limit of allowable H2S concentration in
atmospheric air was officially set at 0.01 mg/li.
Qualitative Reactions
Hydrogen Sulfide Determination with Lead Acetate
The course of H2S reaction with lead acetate is represented by the "follow-
ing equation. . . . .
Pb(CH3COO)2 + H2S ->PbS + 2CH3COOH.
Filter paper saturated with lead acetate solution turns black in the
presence of HgS due to the formation of lead sulfide. Several methods have
been proposed for the saturation of the indicator paper. Two of these are
described below: - .
According to the first procedure of V.A. Khrustaleva and I. K. Yakovemko,
the paper is saturated with a 10% solution of lead acetate and air-dried at room
temperature in an atmosphere free from hydrogen sulfide. Sensitivity of the
method is 0.025 mg/li.
-42-
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Reagents. Lead acetate, 10% solution.
Analytical procedure. The indicator paper is placed where the presence
of HgS is suspected. Development of a black color indicates the presence of
According to the second procedure 10 g of lead acetate are dissolved in
100 ml of 50% solution of glycerol. The filter paper is submerged into this
solution and an excess of fluid absorbed by a small piece of clean filter paper.
The sensitivity of this method is 0 . 01 as compared with 0. OZ5 mg/li of the
first method.
Reagents. Lead acetate, 10% in a 50% glycerol solution.
Analytical procedure. As described just above.
Hydrogen Sulfide Determination with Indicator Tubes
Filled with Lead Acetate Saturated Silicagel
The indicator tubes used in H2S determination, as developed by M.L.
Blagodarov, can be used for qualitative analysis or for approximate quantita-
tive analysis.
Reagents. 1. Lead acetate, 0.75% solution, 2. Granular silicagel of
0.25-0.5 mm diameter.
The indicator tubes should be 100 mm long and 4 mm inside diameter,
drawn out to a point at one end, and filled with the above described size of
granular silicagel saturated with. 0. 75% lead acetate solution. Cotton plugs
should be placed before and after filling the tubes with the silicagel.
Analytical procedure. The air is aspirated through the tubes flowing
from the wider to the narrower end. Results are determined and recorded
by the linear colorimetric method as described on page 3.
Hydrogen Sulfide Determination with Filter Paper
Saturated with Sodium Nitropfusside
The filter paper is moistened with 5% solution of sodium iiitroprusside
mixed with, a 2% solution of sodium carbonate which results in the following
series of reaction.
H2S + Na2C03 -oN
[Fe(CN)«NO] • Na, + NaaS - [Fe(CN)sNOSINa4.
-43-
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Reagents. 1. Sodium nitroprusside, 5% solution. ,2. Sodium carbonate,
2% solution. . : • .
Analytical procedure. Place the paper where HgS is suspected to be
present in the air. In the presence of H2S the paper acquires a red color.
At high HgS concentrations the color may have a violet tint. The reaction
is nonspecific, since in the presence of sulfur dioxide the paper will also
change color. Moist paper will react more rapidly and more sensitively
than dry paper.
Hydrogen Sulfide Determination with Paper Saturated
with Ammonium Molybdate
B.G. Eremina proposed a senstive qualitative reaction for hydrogen
sulfide using filter paper saturated with ammonium molybdate.
Reagents. 1. Ammonium molybdate, 2.5%. 2. Potassium cyanide,
5% solution. 3. Hydrochloric acid, 5% solution.
Saturate narrow strips of paper with a mixture of equal volumes of
reagents, 1, 2, and 3.
Analytical procedure. In the presence of HgS the indicator paper
acquires a violet color. Higher concentrations of HSS produce a red color.
The chemistry of this reaction has not been explained.
Methods for the Quantitative Determination of Hydrogen Sulfide
Linear Colorimetric Method for the Determination of Hydrogen Sulfide
The linear colorimetric method of E.D. Filyanskaya is based on the
formation of lead sulfide as a result of reaction between HgS and lead ace-
tate, which is adsorbed upon powdered porcelain. Filyanskaya proposed
that barium chloride be introduced into the solution of lead acetate for the
absorption of air moisture; in the presence of BaCl2 lead sulfochloride is
formed which increases the reaction sensitivity and with it the length of the
colored indicator layer.
Reagents. 1. Lead acetate, 15% in 2% solution of acetic acid (A)
2. Barium chloride, 2% solution (B). 3. Powdered porcelain (250-315 ju).
Apparatus and dishes.
1. Porcelain dish 15-20 mm diameter.
2. Glass tubes of 0.2-0.3 mm inside diameter and 80-100 mm long.
3. A gasometer (see pages 5 and 6).
4. Electrocorundum.
X
: -44-
-------
Prior to saturating the powdered procelain combine solutions A and B
in equal volumes. A mixture of the powdered porcelain and electrocorundum
is then saturated with the mixed A and B solutions at the rate of 0. 75 ml of
the. solution per 1 g of the dry powder, and dried at 45-50° in clean open air.
Place the indicator powder into sealed ampules where it can be kept for 30
months. Changes in temperature up to + 30° have no effect on the sensitivity
of the reagent, but at higher temperatures the sensitivity of the indicator
powder changes considerably. Place the indicator powder into glass tubes as
described in one of the preceding paragraphs.
Analytical procedure. Aspirate the air to be tested through the indicator
tubes; in the presence of hydrogen sulfide Ln_the air the.indicator powder will
acquire a yellowish brown to black color. Depending upon the concentration
of H2S in the air the author recommends the use of two standard scales: one
covering a range of 0.002 to 0. 05 mg/li and aspirating 250 ml of the air; the
other scale covers a range of 0,01 to 0.4 mg/li and requires 30 mi of aspi-
rated air. In either case the aspiration rate should be 70 ml/min. Relative
air moisture in the range of 30-70% may cause changes in the length of the
colored indicator layer, thereby introducing an error in the results, which
may be as high as 10%. In using the indicator tubes the author recommends
a device, such as described in pages 5 and 6. The same device can be used
for the rapid determination of other substances.
Calculation of results. Results are read on a standardized curve, the
abscissa and ordinate of which represent correspondingly lengths of color-
changed indicator column and H.J5 concentrations in the air. The determina-
tion technique is described on page 4. Sensitivity of the method is 0. 002 mg/li
and the accuracy is ilO% of the determination value.
Determination of Hydrogen Sulfide with Silver Cyanide
The linear colorimetric method used in connection with the indicator
tubes is based on the fact that silver cyanide reacted with hydrogen sulfide
to form silver sulfide, which is of a dark brown color. In this method alumi-
num oxide is used as the indicator powder. The reaction proceeds as shown
below.
ZAgCN + H^ -, Ag^S + 2HCN
Saturate the powdered aluminum oxide with a 10% solution of AgCN, dry
and place into indicator tubes. For the determination of low hydrogen sulfide
concentrations aspirate 750 ml of air.
Reagents. 1. Silver nitrate, 4% solution. Place the activated aluminum
oxide granules (A1SO3) into a 4% solution of silver nitrate, filtered with, the
aid of a Buchner funnel and dry the saturated A12O3 granules at 105° for
30 min.
-45-
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2. Sodium cyanide, 4% solution. Saturate A12O3 powder as above pre-
pared with the sodium cyanide solution and dry.
Apparatus, dishes .and other materials.
1. A rubber suction bulb of 75 ml capacity, or an aspirator. :
2. Glass tubes, 3.5 mm inside diameter, 100 mm long. Reduce the
opening of the glass tubes to 0. 5 mm in diameter.
3. Activated granular Ala O3, 0.25-0.35 mm in diameter. Silicagel
or quartz sand of above mentioned diameter can also be used as the indica-
tor filler.
Analytical procedure. Insert into the glass tubes cotton wads of 2-4 mm
thickness. Overlay with a 5-6 mm of the saturated granulated A12O3; tap the
tube with your finger or against the surface of the table; place another cotton
wad. over the A12O3 indicator; connect the wide-end of the tube to the 75 mm
rubber bulb; by completely compressing and releasing the bulb draw through
the indicator tube a stream of the investigated air. About 3-4 such compres-
sions and expansions of the rubber bulb will suffice for the test. In the
presence of H2S in the air the column of the A12O3 saturated indicator will
become colored, to a length directly proportional to the HgS concentration in
the air. Final estimation is made with a previously prepared linear standard
representing different H^S concentrations in equal volumes of aspirated air.
Determinations are recorded in mg/li within the range of 0.038-0.75 mg/li.
Calculation of results. Compare the length of the colored indicator
column -with a series of previously prepared standard tubes, through which
known air volumes of known HJ5 concentrations have been aspirated. The
results can also be read on a nomograph or standardized curve, or in tables
such as are shown on page 3 .
Determination of Hydrogen Sulfide by the
Ammonium Molybdate and Palladium Sulfate Method
Kobayasi and Kitagava proposed a rapid linear colorimetric method for.
the determination of hydrogen sulfide which is performed as follows: sub-
merge the indicator tubes containing silicagel into a mixture of 5% ammo-
nium moiybdate and palladium sulfate, then dry the material in vacuum at 65°
and 20-25 mm mercury pressure. Aspiration of air containing hydrogen sul-
fide will change the color of a part of the indicator layer from light yellow to
dark blue.
Reagents. 1. Ammonium moiybdate, 5% solution. 2. Palladium sul-
fate, 5% solution. 3. Silicagel, granulated, 0.25-0.35 mm in diameter.
-46-
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Apparatus and dishes.
1. Glass flasks, Klaizen, 50 ml capacity.
2. A suction pump.
3. A pressure gauge.
4. A waterbath. .
5. Glass tubes of-1-2 mm inside diameter.
Sensitivity of the method is 0. 005 mg/li.
Analytical procedure. Aspirate the tested air through the indicator tubes
at the rate of 1 ml/sec. In the presence of hydrogen sulfide the silicagel
indicator will acquire a dark blue color.
Calculation of results. The concentration of H2S in the air is judged by
the length of the indicator layer which changed color from the light yellow .to
the dark blue. The procedure is the same as described for linear colori-
metric methods on page 23. The presence in the air of carbon monoxide,
ethylene, volatile hydrocarbons, arsenic trioxide, phosphines, and of nickel
carbonyl interfere with the reaction. Sulfur dioxide has no effect on the
results.
CARBON BISULFIDE (CS3)
Carbon bisulfide is a colorless fluid having a specific odor; it generally
contains admixtures of decomposition products which impart to it a yellow
color and unpleasant odor. Carbon bisulfide is highly volatile, its b.p. is
46°. Carbon bisulfide vapor is highly inflammable in open air. Its mol.wt.
is 76.14; sp. gr. at 20° is 1.26. Carbon bisulfide vapor is 2.6 times as
heavy as air. One li of CS3 vapor weighs 3.40 g at normal temperature and
pressure.
Toxicology
Several hour's exposure to carbon bisulfide concentration of 1.0-4.5
mg/li in the air may cause acute poisoning. Inhalation of CS3 vapor elicits
irritation of the upper respiratory tract, causes headache, nausea, pain in
the trachea, and induces a feeling of drunkenness. Loss of consciousness
may appear upon exposure to higher concentrations. The limit of allowable
concentration of carbon bisulfide in the air was set at 0.01 mg/li.
Qualitative Reactions
Determination of CSS with the Aid of Diethylamine and Copper Acetate
Filter paper saturated with a mixture of diethylamine and copper ace-
tate solutions acquires a brown color in the presence of CS2.
-47-
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Reagents. 1. Diethylamine, 10% solution in absolute alcohol. 2. Lead
acetate, 5% solution in alcohol. .
Add 5 drops of the copper acetate to 100 ml of the diethylamine solution
and mix. The principle involved in the reaction is as follows: carbon bisul-
fide and diethylamine react to form diethyldiaminodithiomethane; in combination.
with copper the latter forms a complex of a brown color; the following equa-
tions show the course of the reaction.
S-H
+H-N
CAROON
BISULFIDE
CASSONBIS'JIFIDE
X
C!Hi H-S
r
D.ET.YLANI.O.IT.IO.
CARDONBISULFIOE
0 , ET«JD.«,, •«,«.»•
H-S
X
>C<
/ X
-f CuCCH-jCOO),
H-S
DlETHUOIAMI H09ITHIO- COPPiS
KE1HAKE ACETATE"
\N/
CU-OIETHYIBIAHI 110-
METHAJiE
ACETIC ACID
Analytical procedure. Saturate filter paper with, a combined solution
containing copper acetate and diethylamine; cut it into strips and dry. Place
a strip of the paper where the air is to be tested. In the presence of carbon
bisulfide the indicator paper vnll acquire a brown color. The reaction
sensitivity is 1 mg/li. Pyridine can be used in the place o£ diethylamine.
-48-
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Quantitative Determination of Carbon Bisulfide in the Air
Determination of. Carbon Bisulfide with Diethyiamine and Copper Acetate
E.I. Kuz'mina described a method for the determination of CS2 in the
air which, cannot be classed as a rapid method, but which is simple of per-
formance, highly sensitive and specific. The chemical principle of this
method is represented by the preceding series of chemical reactions.
2.
CS.
Reagents. L. Diethyiamine, 2% solution in carbon bisulfide-free benzene.
Copper acetate, 0.1% solution, in methyl alcohol. 3. Standard solution of
Preparation of the standard CS2 solution. Dissolve 1 ml of chemically
pure CSS , which, is equivalent to 1. 25 g, in 20 ml of methyl alcohol in a 100 ml
volumetric flask. Shake and. add methyl alcohol to the 100 nil mark. Take
1 ml of this solution using a measuring pipette and place into a 50 ml volu-
metric flask. Add methyl alcohol to the 50 ml mark. One ml of this CS2
solution should contain 0.000252 g or 0.252 mg of CS,
Prepare the set of standard tubes as indicated in Table 4.
Table 4
TEST \IISE 'io.
Ml OF SOLDI IO1,,,o.. .«».. ..oo
r\G Of C-S2 IK EACH TEST TUiEoo
I
0.1
0,0252
1
0,25
0,063
1 1
3
0,5
0.126
«
1.0
0,252
6
2,0
0,504
Add to each tube 10 ml of
methyl alcohol, 2 ml of the
2% benzene solution of
diethylamine, and 2 ml of
the copper acetate solution
in methyl alcohol and mix
thoroughly. .Leave tubes
stand for 15 min. before
making actual comparison.
Apparatus.
1. Flasks, volume trie 100 ml, 2.
2. Ten colimetric test tubes.
3. Two ml pipettes divided into 0.1 ml.
4. Two ml pipettes divided into 0.01 ml.
5. Four Zaitsev absorbers.
6. One theroiomei2r of O-50° range.
Analytical procedure. Add 10 ml of methanol to each of two Zaitsev
absorbers connected in parallel and aspirate between 500 and 1, 000 ml of
air at the rate of 100 ml/nain. Add to each absorber 2 ml of the diethylamine
solution and 2 ml of the copper acetate. Mix well and leave stand for 15 min.;
pour the content of the absorbers into separate test tubes and compare the
developed color with the standard scale.
-49-
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Calculation of results. Calculate the results using the following formula.
in which C represents mg of carbon bisulfide in 1 li of the air;
A represents the amount of CS2 found by comparison with a
standard scale in the first absorber;
B represents the amount of CS2 found by comparison with a
standard scale in the second absorber;
.V represents, the volume of air aspirated through both absor.bers.
Example. Assume that color intensity in the first and second test tubes
was equal to the color intensity found in tube No. 4 of the standard scale. The
amount of air aspirated through the absorbers was 0.5 li. Compute as follows:
^•0.252+0.251^008 mg
0,3
AMMONIA AND ALIPHATIC AMINES
Ammonia (NH3) is a colorless gas having a characteristic turpetine odor.
Its mol. wt. is 17,031; one ml of ammonia at O° and 760 mm mercury
weighs 0.7714 mg. Sp. gr. of ammonia as compared with air is 0.5967.
Molar volume is 22.08. Ammonia gas is more soluble in water than any other
known gas: 1 volume of water at O° absorbs 1200 volumes, and at 20° 700
volumes of NH3
Aliphatic amines are compounds -which can be derived from ammonia by
substituting the hydrogen atoms by hydrocarbon radicals. Thus, methyl-
amines, diethylamine, and triethylamine are gaseous substances, while all
lower amines are fluids which have the odor of ammonia. Like ammonia,
lower amines are easily soluble in water, forming alkaline solutions. As
the mol.wt. of the amines increases the solubility in water decreases. Below
are described properties of methylamine and ethylamine.
Methylamine (CHflNH3) is a colorless gas having a characteristic odor of
ammonia: its mol.wt. is 31.06. One ml of this gas at O° and 760 mm mercury
weighs 1. 388 mg; the sp. gr. of this gas as compared with air is 1. 0737: its
mol. vol. is 22. 37.
Ethylamine (CS3CHgNHa) is a volatile liquid having a boiling point of 16. 6°;
1 ml of ethylamine at O° and 760 mm of mercury weighs 2.0141; its mol. vol.
is 22.37.
-50- '
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Toxicology
Ammonia has an irritating effect on the upper respiratory passages. At
0.15-0.25 mg/li ammonia causes sneezing, salivation, nausea, headache,
reddening of the skin, and at higher concentrations strongly irritates the eye
and nose mucosa, causes vomiting and excruciating stomach pain, and stimu-
lates the nervous system. The limit of allowable ammonia concentration in
atmospheric air was officially set at 0.02 mg/li. The toxic effect of aliphatic-
amines increases with the increase of the number of carbons in the molecule.
Amines cause central nervous system disturbance. Monoamines are less
toxic than diamines. Unsaturated hydrocarbons are more toxic than the satu-
rated. The limit of alio-wable concentration^ of a li-phaiic amines-has been
officially set at 0. 3 mg/ii.
Determination of ammonia and aliphaticamines is based on the same
principle, therefore, they are included in the section dealing with inorganic
substances. The following methods are recommended as the simplest, most
precise and most rapid.
Qualitative Reactions
Determination of Ammonia by the
Para-Nitroaniline and Bromophenol Blue Method
E.G. Yeremina described a quantitative method for the determination
of ammonia in the air by the use of filter paper saturated with the above
mentioned reagent. Two methods are here described.
Saturate filter paper with a 0. 5-1. 0% solution of hydrochloric acid which
contains several granules of sodium nitrite. In the presence of ammonia in
the air the filter paper changes its original yellow color to red. The reaction
is nonspecific; its sensitivity is 0.0025 mg/li.
Reagents. 1. Para-nitroaniline, 0.5-1.0% solution. 2. Sodium nitrite,
crystalline.
The solution with which the filter paper is saturated should contain 0.05%
solution of bromophenol blue acidified \vith hydrochloric acid at the rate of
2-3 drops for each 10 ml of the solution; add about one or two ml of glycerine.
Analytical procedure. See page 30.
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Determination of Ammonia by the Bromophenol Blue Method
Saturate filter paper with a solution of bromophenol blue; in the presence
of ammonia in the air the original yellow color will change to blue. Other
basic, substances interfere with this reaction.
Reagents. 1. Bromophenol blue, 0.02% solution. 2. Sulfuric acid,
5% solution. .3. Glycerol, c.p.
Analytical procedure. See page 30.
Intensity of changed color varies with the con.cejntration.of ammonia in
the air, making possible the quantitative determination of ammonia in the air.
Determination of Ammonia by the Phenolphthalein Method
The presence of ammonia is detected by indicator paper saturated with
1% solution of phenolphthalein.
Reagents. 1. Phenolphthalein, 1% solution.
Analytical procedure. Moisten, the, indicator filter paper in distilled
water and expose to the air in which the presence of ammonia is suspected.
Development of a red color may indicate the presence of ammonia. Experi-
ence has shown that the appearance of red color within one minute indicated
the presence of ammonia in 0.07 mg/li concentration, and appearance of the
red color in 5-6. 5 sec. indicated the presence of 10 parts per million of
ammonia in the air. This method yields reliable results in the presence of
low carbon dioxide concentrations in the air; higher CO3 concentrations inter-
fered with the accuracy of the reaction.
Determination of Ammonia by the Methyl Violet Method
Prepare indicator paper for this method by saturating it with a solution
of methyl violet acidified with diluted HC1 until the solution turns yellow. In
the presence of ammonia in the air the yellow color changes to bluish violet.
Reagents. Methyl violet, saturated solution. -
Analytical procedure. See page 30.
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Determination of Ammonia by a Solution of
Acidified Fuchsin .
I.M. Kore.nman described a method by which ammonia can be detected
in the air in concentration as low as 0.025 mg/li. Saturate the filter paper
with an aqueous solution of basic fuchsin acidified by a dilute solution of
HC1 until the basic fuchsin will acquire a light yellow color. In the presence
of ammonia in the air the light yellow of the saturated color will turn red.
Reagents. . Basic fuchsin, saturated solution.
Analytical procedure. See page 30.
Quantitative Method for the Determination of Ammonia in the Air
The Bromophenol Blue Method
E.D. Filyanskaya developed a linear colorimetric method which is based
on the fact that in the presence of ammonia the original yellow color 'of the
bromophenol blue indicator acquires a blue color. . . .
Reagents. 1. Bromophenol blue, 1% solution. 2. Ground porcelain of
260-300 y, in diameter.
Accessories.
1. Indicator tubes 70-80 mm long and 0.3 mm inside diameter.
2. Porcelain dish, 15 cm in diameter.
Prepare the procelain indicator by saturating the ground porcelain with
1% solution of bromophenoTblue used in proportion of 1:10. Dry the ground
bromophenol blue saturated porcelain at room temperature and place into the
indicator glass tubes as described in some of the preceding paragraphs.
Analytical procedure. Aspirate the air through the indicator-containing
tube; in the presence of ammonia vapor or of aliphatic amines in the air the
color of the indicator material will change. The length of the color changed
indicator is proportional to the concentration of NH3 or of the aliphatic
amines present in the air; on this basis quantitative determinations can be
easily made.
Calculation of results. See page 4.
Sensitivity of the method is 0.002 mg/li.
-53-
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The Indicator Filter Paper Method
Deckert described a method for the rapid determination of ammonia and
.of alypatic amines, including mono-, di-and triethylamines and also of
ethylene oxide. The method is based on the property of the substances
mentioned to decolorize filter paper indicator saturated with a solution of
ferric cyanide. The degree of color fading is directly proportional to the
stoichiometric ratio between the Fe (CNS)3 and ammonia or amines; on this
basis it is possible to make quantitative determinations of the substances in
the air. The dried indicator filter paper will keep well at 18-20° in tightly
stoppered dark glass bottles.
Reagents. Ferric cyanide, 3% solution.
Accessories.
1. Filter paper.
2. 100 ml cylinder graduates.
Analytical procedure. The determination is based on a comparison, of
the color developed by the indicator paper with a standard color scale.
Sensitivity of the method in the case of rnonomethylamine is 0.132 y, in the
case of dimethylamine the sensitivity is 0.192 y; in the case of trimethyl-
amine the sensitivity is 0.252 y; in the case of ethylene oxide the sensitivity
is 0.188 y, and in the case of ammonia it is 0. 07 y per 1 li of air.
Calculation of results. See page 15.
The Bromothymol Blue Method
for the Deter mi nation of Aliphatic Amines
The method was proposed by L,. A. Mokhov and N.S. Mareeva for the
quantitative determination of aliphatic amines in the air. The method is
based on the reaction taking place between aliphatic amines and bromothymol
.blue which develops a. dark green color. Use silicagel as the indicator
carrier.
Reagents. 1. Bromothymol blue, 0.1% solution in alcohol. 2. Granu-
lated silicagel, 0.25-0.35 mm in diameter.
Preparation of the indicator silicagel and of the tube. Place 1 g of the
purified silicagel granules, dried at" 600°, into a dish and add 3 ml of 0.1%
of bromothymol blue solution in alcohol. Mix well, dry in atmospheric air
occasionally stirring the material to prevent clumping; the air must be free
from ammonia and from aliphatic amines. Place the granulated silicagel
indicator into hermetically sealed containers and keep in dark colored
bottles or in a dark room. The indicator tubes should be 50 mm long and
-54-
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3-3. 5 mm in diameter, sealed at one end and slightly widened at the other
end. Place cotton wads at the sealed end of the tube followed by a 3-4 mm
packed layer of the silicagel indicator, and plug with a 2 mm layer of cotton.
Accessories.
1. Glass tubes, 50 mm long and 3-3.5 mm inside diameter.
2. Glass wool.
3. Syringe, 200 ml divided into 10 ml.
4. Glass container, 25 li capacity.
Analytical procedure. Aspirate the air for the determination of aliphatic
amines through the indicator tube by the syringe up to a volume at which the
silicagel indicator will acquire a bright intense green color.
Calculation of results. The concentration of aliphatic amines is found
on a graduated curve at a point corresponding to the volume of air aspirated
for the production of the dark green ring. See pages 3 and 4.
Prepare the standard curve as was previously described for other
standard curves by aspirating through'a series of indicator tubes air con-
taining known concentrations of the substance in known volume. In the actual
preparation of such standard curves check tests should be made by the titri-
metric method. The procedure is general and standard and should require
no detailed description. The presence in the air of HSO2, of nitrogen oxides,
benzene, toluol, ether, or chloroform does not interfere with the reaction.
The sensitivity of the method is 0. 005 mg/li.
ARSENIC HYDRIDE OR ARSINE (AsH3)
Arsenic hydride is a colorless gas which is odorless in pure form but
acquires an odor of garlic when exposed to the air. The gas is insoluble in
water and slightly soluble in alcohol and in ether. Its mol.wt. is 77.93;
1 ml of the gas at O° and 760 mm mercury weighs 3.48 mg; sp. gr. of the gas
as compared with air is 2. 692; its mol. vol. is 22. 39.
Toxicology
AsH3 is a highly potent poison which affects red blood cells by first
breaking them down and forming methemoglobin. Circulating through the
blood system AsH3 attacks the kidneys and the liver. In the course of AsH3
poisoning there first appears a period of pseudo well-being (occult period)
which lasts for about 3 to 8 hours; then follow different attacks upon the
organism in general, the gravity of which depends upon the concentration of
the AsH3. The symptoms are weakness, headache, vertigo, epigastric pain,
chills, high temperature and nausea. In grave cases of AsH3 poisoning the
-55-
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skin acquires a bronze color, turning later into a light jaundice color. The
urine appears bloody. Unconsciousness and convulsions may appear. The
limit of allowable AsH3 concentration in the air was officially. set at 0.003
mg/li. Several methods have been proposed for the quantitative determina-
tion of AsH3 in the air. The methods described below are characterized by
high sensitivity, ease of manipulation and rapidity of determination.
Qualitative Reactions
The Silver Nitrate Method
This method is based on the fact that AsH3 reacted with silver nitrate
according to the equations indicated below.
3 + 6AgN03->AsAg3-3AgNOj+3HNO3;
AsAg3-3AgN03 + 3H20 -> 6Ag + As(OH)34-3HNO3.
According to these reactions free silver is formed which produces a
yellowish color in small quantities and black color of different intensities
in high AsH3 concentrations. Saturate the indicator filter paper with a silver
nitrate solution-.
Reagents. Silver nitrate, saturated solution.
Analytical procedure. Place the silver nitrate -saturated paper fox one
minute where the air is suspected of containing AsH3.
Quantitative Determination
The Mercuric Chloride Method
M. Bal'skaya described a method based on the reaction taking place
between AsH3 and HgCl2 as a result of which a yellowish brown color is
formed on the indicator filter paper. The reaction proceeds as indicated
below.
Sensitivity of the method is 0. 2 y per li of air.
Reagents. 1. Mercuric chloride, 5% solution. 2. Ethyl alcohol.
3. Lead acetate, 1% solution. 4. Cuprous chloride (CuCl), 1% solution in
1% of hydrochloric acid. 5. Sodium chloride, 1% solution containing 1%
sodium carbonate. 6. Potassium iodide, 15% solution. 7. Arsenic hydride
(AsH3), 0.1% solution.
-'56-
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Apparatus. Sanger-Black apparatus.
Analytical procedure. Submerge filter paper into 5% solution of
for 15 minutes. Dry and cut into strips several mm wide and 20 mm long.
Dissolve the HgCl3 in a small quantity of alcohol; gradually add water to make
a 5% solution. Dip the filter paper into this solution repeatedly. Allow solu-
tion to drip down and dry in a dark room in horizontal position. Place the
strips cf HgCla saturated filter paper into glass tubes so as to allow the aspi-
rated air to permeate through it. The volume of air thus passing through the
paper is carefully measured by means of a syringe.
Hydrogen sulfide, phosphorus hydride, antimonous hydride and suHu-r
dioxide also change the color of the paper; therefore, in the determination of
AsH3 their effects mast be eliminated. This is accomplished by first passing
the air through filter paper saturated with a mixture of lead acetate and sodium
chloride solutions containing 1% of soda, sodium sulfate and cuprous chloride
dissolved in hydrochloric acid for the purpose of removing the interfering
substances. Treat the filter paper through which the purified air containing
the AsH3 has passed with a 15% solution of potassium iodide which will pro-
duce a well defined light yellow to dark brown color, depending upon the con-
centration of the AsH3 concentration in the air. Dry the paper by compress-
ing it between 2 clean filter papers and compare the final color of the indica-
tor filter papers and compare the final color of the indicator filter paper -with
a star.da.rd color scale as described on page 15.
Sanger-Black devised an apparatus for use in the prepara-
tion of this scale as shown in Fig. 11 with the aid of which
the As present in the solution in the form of any compound
can be determined. Place a carefully weighed quantity of
As3O3 into the flask of the apparatus and add a few zinc
granules followed by the addition of 5 ml of 1:2. dilution of
sulfuric acid. The resulting reaction will produce AsH3
according to the following equation:
As203-f6Zn7-6H2SO<
6ZnSO,4-3H2O.
Blow oat the entire volume of formed AsH3 of the flask by
forcing into it a known amount of pure air, and force it
through a paper saturated with HgCl2. After the color has
formed on the paper treat It with, potassium iodide as pre-
viously described.
I - COM! CH Ft.VS.
2- S30U«5-TO-FIT COTTJ»
flUEO SUSS TUH. 3 - IOHS-
SrEflSEO FUHEt. 4- ISJI CA-
TCH MCE*.
-57-
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Calculation of results. The absolute amount of.AsH3 corresponds to the
volume of air blown into the flask and is computed in terms of mg/li accord -
. ing to the following formula. . .
^0.79- n '-1000
';'.-.'.- • • ' • ..v •
in which C represents the AsH3 concentration per li of air;—'
n represents the weight of As2O3 taken for the analysis;
V represents the volume of air passed through the tube.
Exampler- As-sume-that -0-. Ot2-mg- of the. As-sO3 was- taken, for the analysis;
assume further that 250 ml of air was passed through the tube; determine the
As3 concentration in mg/li which corresponded to the color of the paper as
determined by the volume of generated AsHa Accordingly,
;c_ 0.79.0.012.1000 _nmfl mg/li
i . 250
The series of standard colors are prepared by an artist using appropri-
ate water colors and a procedure such as has been described in connection
with other similar determinations. By this method AsH3 concentrations
ranging between 0.0002 and 0.003 mg/li can be determined accurately.
Other investigators are of the opinion that the concentration range can be
extended to 0. 006-.mg/li. "
ANTIMONOUS HYDRIDE (SbH3)
Antimonous hydride is a colorless gas having an odor reminiscent of
hydrogen sulfide. It is soluble in water in 1:5 ratio. It is more soluble in
organic solvents: one volume of carbon bisulfide absorbs 250 volumes of
SbH3. Its mol. wt. is 124.78. The gas decomposes at 150°.
Toxicology
The effect of SbH3 on the organism is much the same as that of AsH3: it
destroys red blood cells and affects the central nervous system to a somewhat
lesser degree.; The symptoms are: headache, weakness, nausea, vomiting,
slow respiration or arhythmia and a rapid pulse. The limit of allowable
_!/ Such a concentration is theoretical and indicates that the color acquired
by the paper represented a certain AsH3 concentration.in the air. A series
of determinations is thus made with different AsH3 concentrations for the
preparation of a standard scale.
-58-
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concentration of SbH3 in the air has not been officially established. Ameri-
can industrial hygenists at their conference in 1949 adopted it as 0.0005
mg/li according to Lazarev.
Quantitative Determination Methods
The Silver Nitrate Method
This method was recommended by Webster; it is based on the reaction
taking place between SbH3 and silver nitrate applied to filter paper. The
reaction produces a grayish brown color and .proceeds according to the
following equation.
The colors produced by AsH3 and SbH3 are sufficiently different to make
possible differential determinations.
Reagents. 1. Silver nitrate, 1% solution. 2. Filter paper, ash-free.
Dishes.
1. Glass beaker, 100 ml.
2. A dark colored reagent glass bottle with ground-to-fit stopper.
3. .Evaporating dish, 3-10 cm diameter.
Analytical procedure. Moisten a 10-70 mm filter paper in 1% solution
of AgNO3. Run off excess of solution; dry suspended at room temperature;
the paper should remain colorless and must contain a slight amount of
moisture; store in dark colored glass bottle with ground-to-fit stopper. In
this condition the indicator paper will keep for more than 2 months.
In making the analysis remove the indicator paper from the glass bottle
and expose to the air suspected to contain SbH3 for one minute, or aspirate
some of the air by suction through the indicator paper as described in connec-
tion with the previously outlined text.
Calculation of results. Determine the SbH3 concentration by comparing
color intensity produced in the indicator filter paper with an artificial water
color standard series as previously described for A sH3 on page 53. The test
is nonspecific, since traces of hydrogen sulfide interfered with the determi-
nation.
-59-
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(F2)
..Fluorine Is a colorless gas having a sharp pungent odor. Fluorine
rea'cts as follows with water,. . •
:V ' . • - F2+H2O-2HF+O, ;
The .free O thus formed immediately combines to form ozone (O3) according
to the following equation; • , ' ... .
The mol. wt. of fluorine is .38. 00. One ml of the gas at O° and 760 mm of
mercury weighs 1. 695 mg. Its.sp. gr. .in relation to air is 1. 311, its mol.
;vpl.; is. 2Z.42, and its.b.p.Vis 33. 95°. - \ .'. '
; : '.> . ' '•'•''.- ''••'. ... Toxicology
•' 'Flu bid ne sharply irritates-the mucous membrane of the respiratory
tract. It permeates easily into the "blood system eliciting general systemic
poisoning. However, direct pbiso.ning with fluorine as such seldom occurs,
'due to the fact that in contact with air fluorine rapidly forms HF. The limit
of allowable fluorine concentration in the air has not been officially estab-
lished. . ..-..'•-..• .
'•.;'.'" Quantitative Determination Methods
. The. Zirconium Oxychlbride Method
Kabayasi described a rapid quantitative method for the determination of
fluorine using a filter paper indicator. The method is based on the fact that
the reaction taking place between F2 and zirconium oxychloride (ZrOCls) in
the presence of p-dimethylaminoazobenzarsenite produced a colorless ZrF4
and free azobenzenenearsenious acid which is of a red color. The reaction
takes place in. acid medium. Concentrations of F3 in the air as low as
0. 0014rng/li can be detected by this method. The reaction is non-specific,
since the presence of hydrochloride, phosgene, chlorine, bromine and iodine
interfered with the reaction. •
Reagents. 1. Methyl alcohol^ 2. Filter paper, a.sh-free. 3. Hydro-
chloric acid, Z M solution. 4. Zirconium chloride. 5. p-dimethylaminoazo-
benzenearsenious acid. 6. Ethyl alcohol, redistilled. .
-60-
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Preparation of the solutions. Prepare solution of zirconium oxychloride
by dissolving 10 mg of the reagent in 10 ml of 2 M solution of hydrochloric
acid. Prepare reagent 5 by dissolving 25 mg of the para-reagent in 100 ml
of a mixture of methyl alcohol and HC1 of 1. 15 sp. gr. in 9:1 ratio.
P_r_e_p_a_ratign_qf_t_he_ indi_c_a_tpr_p_ai2er. Submerge filter paper into reagent 5
for one minute. Remove and dry in the dark in a fluorine free atmosphere;
saturate the paper with solution 4 by dipping it for 10 minutes; wash in a cold
solution of 2 M HC1 for 5 minutes; wash a second time in the same solution at
50°. Rinse in cold water and ethyl alcohol, and suspend in a dark room until
dry. The indicator paper will acquire a canary-yellow color with a slight
brownis-h tint. It can be stored for 8 hau-rs- wttho-ut-colo-r change-.
Dishes.
1. Glass beaker, 100 ml.
2. Dish evaporating, 8-10 cm in diameter.
Analytical procedure. Moisten the indicator paper with 2 M HC1 just
before use. Make quantitative determination by comparing the final color
after exposure to the tested air with a previously prepared standard color
set. Prepare standard color set by passing air-containing known concentra-
tions of fluorine through the filter paper in a room the air of which is free
from fluorine. The standard set should cover the range of 0.001-0.008 mg/li.
Calculation of results. As shown previously on page 58.
SULFUR DIOXIDE
(SULFUROUS ANHYDRIDE, OR SULFUR DIOXIDE, SO2)
Sulfur dioxide is a colorless gas having a characteristic sharp odor. It
is highly soluble in water and can form a 10% solution, which is equivalent
to a solubility of 40 volumes of the gas in one volume of water. Its mol.wt.
is 64. 06. One ml of the gas at O° and 760 mm of mercury weighs 2. 926 mg.
Its sp. gr. in relation to air is.2. 2635, and its mol. vol. is 21. 89.
Toxicology
SO3 is highly irritating to the upper respiratory tract, and in higher con-
centrations is also irritating to the lower respiratory passages. In contact
with moist mucosa SOa converts to sulfurous acid followed by conversion to
sulfuric acid. The toxic effects are probably due to the presence of the
sulfuric acid. SO3 is irritating to the eyes and to the hemopoietic organs.
It permeates into the blood circulation forming methemoglobin. The follow-
ing are symptoms of SO3 poisoning: irritation of the respiratory organs and
of the eyes, chest pain, lacrimation, hoarseness, headache, vertigo,
-61-
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coughing, and pain in the epigastric region; Cases of. chronic SO2 poisoning
have occurred as the result of prolonged exposure to low SQa concentrations.
.The limit of .allowable SO3 concentration in the air has been officially set at
Q. 01 mg/li. . . :
Qualitative Determinations of SOa
. The Potassium Oxyiodide Method .
. .B.G. Yeremina recommended the use of filter paper indicator for the
detection of SO3. Prepare the filter paper as follows: mix 1% solution of
potassium oxyiodate with an equal volume of 1% solution of soluble" starch" -"
slightly acidified with HaSO4 or HC1. Then saturate strips of.filter paper
with this solution and place where the air is suspected to contain SOS. In the
^presence of SO2 the filter paper turns blue, but upon prolonged exposure the
color disappears. The reaction is as follows:
Reagents. 1. Potassium oxyiodate, 1% solution. 2. Starch, soluble,
1% solution. 3. Sulfuric acid, 10% solution. -.
Analytical procedure. See page 30.
The reaction does not occur at high SO3 concentrations, and at prolonged
exposure of the indicator paper to air containing SO2 it may become decolor-
ized. The presence in the air of nitrogen oxides and of hydrogen sulfide
interfere with the reaction. .
The Nitroprusside Method
Saturate filter paper with a solution containing 5% sodium nitroprusside
and 2% soda; in the presence of SO3 in the air the indicator paper acquires a
red color and at high SO2 concentration the color turns blue.
Reagents. 1. Sodium nitroprusside, 5% solution. 2. Sodium carbonate,
2% solution. . .
Analytical procedure. Expose the paper for about 2-3 min. to the air for
the detection of SO2. The reaction is nonspecific, and the presence of H2S
.interferes with the determination. Moist paper reacts faster than dry paper.
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The Mercurous Nitrate Method
Woog proposed a sensitive method for- the qualitative determinations of
sulfurous anhydride which can be represented by the following equation:
Expose the paper saturated v/ith 5% of the mercurous nitrate solution to
the air; in the presence of SOa the paper will turn black with a metallic sheen
due to the liberation of mercury. The reaction is nonspecific, since NH3 and
HSS interfere with the reaction.
Reagents. I. Hga(NO3)3 solution, 5%. .
Analytical procedure. See page 30.
Quantitative Determination
The Potassium lodate Method
This method was developed by N.I. Fomicheva. The reaction is based
on the reduction of iodate to elemental iodine in sulfuric acid medium. As
the elemental iodine is set free the starch turns blue. The reaction can be
represented by the following two equations:
-» KI + 3H2SO<;
KI034-5K:
In th.e presence of insufficient KIO3 and high SOS concentrations the
developed blue color rapidly fades out. In the presence of moderate or low
SOa concentrations, which occur in the air most frequently, and in the pres-
ence of adequate K1O3 concentration the blue color developed by the indicator
persists for a long time. Use silicagel as the indicator carrier.
Reagents. 1. Potassium iodate, 1% solution. 2. Starch, soluble, 1%
solution. §7~ Silicagel, dried at 300°, granular of 0. 3-0. 5 mm diameter.
Dishes and auxiliary materials.
1. Porcelain dish, 10 cm diameter.
2. Cylinder graduate, 100 ml.
3. Glass tubes, 0.5 mm inside diameter, 50-60 mm long.
4. Hygroscopic cotton.
5. Aspirator such as shown in Fig. 6, page 7. Prepare the indicator
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as follows: place 2 g of the above" described dry silicagel in a porcelain
dish and add 2 parts of 1% KIO3 solution, and l.part of freshly prepared 1%
.solution: of soluble starch. Mix and leave stand at room temperature for
30-40 min. then dry at 25-30°. Pour the, free-flowing silicagel indicator
"granules into .glass tubes as specified under 3, until the silicagel layer
measures 10-12 mm. Plug both ends of the tube with cotton, seal by fusing,
and store for future use. .
Analytical procedure. Open both ends of an indicator containing tube,
and aspirate through it 360 ml of air at the rate of 12 ml/min. at optimum
temp._ of. + 30°, but not higher, .since at higher temperatures the free iodine
-will vaporize before becoming adsorbed by the starch.
Calculation of results. See page 3 for linear colorimetric method.
Presence of H3S interferes with the reaction. The method can detect
0.002-0.1 mg/li of SO2 in the air.
The originator of the method noted that aspiration of the tested air
through the indicator tube will change, the color of the indicator column to
a length directly proportional to the SO2 concentration in the air. Changes
in humidity, the presence of H2S,. of nttrogen oxide, and of sulfuric acid
aerosol interfere with the reaction; therefore, the present authors intro-
duced a special device for the preliminary absorption of the interfering sub-
'stances by the following solutions: 1. Zinc chloride 10% in 0.01 N NaCl;
2. Sodium nitroprusside, 20% solution, to which add 2.4 ml of glycerol
diluted with equal volume of water; 3. Urotropin 20% solution. Use only
freshly prepared solutions; 4. Ground procelain of 0.16-0.25 mm diameter.
Prepare adsorbent as follows: Place 10 g of the granulated porcelain
into, a porcelain dish, add 0.2 ml of reagent 1, mix.thoroughly with a glass
rod to even distribution; add to this 0.5 ml of reagent 2, again mix well
with a glass rod to insure even moistening of the granulated porcelain, dry
in'a current of air until the ground procelain becomes free-flowing. Add
0.5 ml of reagent 3, again mix well and again dry in a current of air. Dis-
tribute the final sorbent into glass tubes, seal hermetically and store for
future use; use glass tubes of 2. 5-2.6 mm in diameter and fill them with the
indicator sorbent to column length of 65-70 mm. The sensitivity of the
method is 0.2 mg/li of SO2.
In taking samples of air for the determination of SO3 use a filter adapter,
which can also be used for the absorption of hydrogen sulfide, nitrogen
dioxide and sulfuric acid aerosol; the filter adapter consists of a glass tube
12 mm inside diameter, 92 mm long; reduce tube opening at one end to 5 mm
and at the other end to 8 mm; fill it with three types of granulated material.
suitable for (the absorption of the above mentioned interfering air pollutant
components:.
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Preparation of_£qwdered_abs_qrbe_r. Prepare the powdered material for
the absorption of nitrogen dioxide as follows: use fire-clay, the particles of
which measure 0. 8-1. b mm in diameter and add 0. 7 ml of 10% solution of
diphenylamine for each gram of the fire-clay, stir well, dry at room tem-
perature, place into ampules, seal hermetically and store.
Pr_ep_ajre_ the pp_wde_r /or _th_e_ abs orptipn_ of Ey5 and_wate r vapor as follows:
grind 10 g of copper sulfate to a powder in a mortar; pour into a glass beaker,
add 10 ml of distilled water and boil until the copper sulfate dissolves. Then
add 10 g of the fire-clay (chamotte), mix well and heat until the copper sul-
fate solution is completely absorbed by the fire-clay. Transfer the 'material
to a-porcelai-n dish and heat a±~2£00 for 1 hr. Separarte the saturated" fire~-clay —
from the residual copper sulfate solution by passing it through a sieve of
0.8 mm gauge; place into glass ampules, seal hermetically and store.
Prepare the_ jgranulated calcium chlorid_e as follows: place some dry
calcium chloride in a porcelain dish, continuously mixing same until the
material becomes free -"flowing; pass through a sieve of 0.8-1.6 mm gauge;
place the CaCLj granules into an evaporating dish and again dry at 180-200°;
place into glass ampules, seal hermetically and store.
Fill the filter a-da_p_ter_with_ Jh^s__mate_riaj._a_s_ JoLlow_s_: place a cotton plug
5 mm thick at one end of a glass tube and overlay with a 10 mm column of
dry CaClg followed by a 50 mm layer of copper sulfate prepared as previously
described, and by a layer of diphenylamine; insert cotton plugs, cover with
a rubber cap and store for future use.
The Potassium Iodide Method
A. Kxynskaya recommended the use of an indicator mixture which
changed color from light blue to brilliant blue depending upon the concen-
tration of SOS in the air.
Reagents. 1. Nitric acid, concentrated, 1.4 sp.gr. 2. Sulfuric acid,
c'. p. 3. Potassium iodide, c.p. 4. Starch, soluble. 5. Granulated
siiicagel, 0. 4 -0. 7 mm diameter .
P_r_epa ration_ of the ind_ic_ator _ma_teri_al_and_qf_ the jndica_tor_tube_s_. "Wash
the silicagel with concentrated nitric acid and 12% solution of sulfuric acid;
remove the acid by continuous washing with water and dry at 200-300°; again
wash with a mixture of 2 parts by weight of 1% solution of potassium iodide
and 1% solution of soluble starch; remove excess of solution and dry the
indicator powder until it becomes free-flowing and pour into tubes 3-3.5 mm
in diameter and 60 mm long to columns of 5-6 mm long; place cotton plugs
at each end of the tube and seal hermetically.
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Apparatuses. •
1. Porcelain dish, 10-12 cm in diameter.
2. Glass beaker, 100 ml.
3. Cylinder graduate, 50 ml.
4. Glass tubes, inside diameter 3 mm, length 80-100 mm.
5. Air aspirator, such as illustrated by Figures 2 and 3 on page 6.
Analytical procedure. Cut the tubes open at both ends with the aid of a
glass file and aspirate 300-500 ml of the tested air.
Calculation of results. Record and compute final results' ars-des-crrbed1 on—
on page 15. Sensitivity of the method is 0.001 mg of SO3.
the Filter Paper Method
Scott proposed a filter paper method for the determination of sulfur
dioxide based on the reaction previously described in connection with the
method of N. I. Fomicheva. In the presence of SO2 the filter paper acquires
a violet color of different intensities, depending upon the concentration of
the SO3 in the air. The method is not specific and the chemical principle
and reactions are as described on page 63.
Reagents. 1. Starch, soluble. 2. .Sodium hydroxide, 0.1 M solution.
3. Potassium iodate, c.p. 4. Potassium iodide, c.p, 5. Glycerol, puri-
.fied. 6. Filter paper.
Preparation of the reagents. Take 5 ml of 0.1 M solution of NaOH and
add to it 80 ml of distilled water; mix well. Dissolve 1 g of soluble starch.
in 10 ml of the above prepared solution and mix well to a paste consistency
and add gradually with continuous stirring to 75 ml of boiling water. When
the entire starch paste has been added and evenly distributed add 3 g of KIO3
and 2 g of KI. Boil with continuous stirring to complete dissolution; cool
and add 15 ml of glycerol with continued mixing.
Dishes.
1. Cylinder graduate 100 ml.
2. Pipettes, graduate, 20 ml. .
3. Glass beakers, 150-200 ml.
Analytical procedure. Cut filter paper into strips 20x60 mm and dip
into the prepared solution for 1 min. ; allow excess solution to run off and
dry the paper for about 1 hr. at not more than 60° in an atmosphere free of
sulfur dioxide. The final indicator paper should be absolutely colorless and
should contain a slight amount of moisture. Store the paper in dark glass
ground-to-fit'stoppered bottles'; Under such conditions the indicator paper
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should keep for 4 months.
Calculation of results. As described on page 3.
Sensitivity of the method is 0.0036 mg/li.
MERCURY VAPOR (Hg)
Mercury is a liquid metal. Its atomic weight is 200.6, b.p. 357.2°
One ml of Hg at 20° and 760 mm of mercury weighs 8.24-mg. The metal
vapo.rize.s at normal temperature. The amount of Hg in the air depends_
upon the temperature as shown in Table 5 below:
Table 5
MERCURY VAPOR TENSION
TEMPER-
ATURE
15°
20°
25°
30°
35°
VAPOR TENSION IK
MM OF MERCURY
COLUMN
0.00069
0.00109
0.00168
0.00257
0.00387
TEMPER-
ATURE
40°
SO"
60°
80°
100°
150°
VAPOR TEHSIOH |H
MM OF MERCURY
COLUMN
0.00574
0.0122
0.0246
0,0886
0.276
17,81
Toxicology
The toxicological properties of Hg are basically those of its vapor, which
penetrates through the respiratory tract into the blood stream causing grave
acute and chronic poisoning. The acute symptoms appear under conditions
of mercury vapor coming from heated surfaces creating high concentrations
in the air; chronic poisoning usually results from slow mercury vaporization,
into the air at normal temperature. In cases of acute poisoning mercury
vapor affects basically the digestive tract and the kidneys; in chronic poison-
ing Hg affects basically the nervous system. The following symptoms have
been noted in grave cases of Hg poisoning: metallic taste in the mouth,
nausea, pain in the intestinal tract, bloody diarrhea, headaches, cardiac
weakness, and convulsions. This is usually followed by inflamation of the
gums and of the oral mucosa. The next stage is characterized byhemolysis,
sleeplessness, headache, facial tics, trauma of the digits, deliriousness and
hallucinations. Such symptoms frequently end in death of the patient as the
result of extreme exhaustion. The limit of allowable mercury vapor concen-
tration in the air was set officially at 0.00001 mg/li.
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Q ualitative Reaction
The Iodine Method
The N.G. Polezhaev method is highly sensitive and widely used for the.
.qualitative determination of Hg in the air. The method is based on the
reaction between Hg and iodine which forms mercuric iodide (Hglg). The
latter reacting with KI results in the formation of a complex according to
the following reaction: '
When anion Hgl^1 reacts with a copper salt in the presence of a reducing
agent a complex salt forms Cug iHgI4 J , which is of a rose color. The
reaction proceeds as follows: •
4KI -1- 2CuSO4
The sensitivity of the method is .0.0001 mg/li.
Reagents. 1. Cuprous sulfate, 10% solution. Z. Potassium iodide,
10%. solution. 3. Sodium sulfite, 0. 5-1% solution. 4. Nitric acid, L2sp.gr.
5. Ethyl alcohol, 96°. . .
Mix equal volumes of 10% solution of copper sulfate and 10% solution of
potassium iodide; allow the formed precipitate to settle and decant the super-
natant brownish solution. Wash the precipitate with distilled water to com-
plete removal of the iodine. Again wash the precipitate with 0. 5-1% solution
of potassium iodide and 5% solution of sodium sulfite and wash twice with
distilled water. Siphon off supernatant wash water from the precipitate as
completely as possible; transfer the precipitate into a jar or a beaker, and
add ethyl alcohol to the formation of pasty mass. Then add a drop at a time
25% of nitric acid, or approximately 1 drop of the acid for each 50 ml of the
pasty mass; spread the pasty mass in a thin even layer over strips of filter
paper; dry in the open air and store in a desiccator. The paper will acquire
a yellowish-rose color. It is now ready for use.
Analytical procedure. Place the indicator paper where Hg is suspected
to be present in the air, or aspirate the air through a tube containing the
paper as illustrated in Fig. 5 on page 7.
In the presence of Hg in the air the original yellowish-rose color of the
filter paper will turn red. .
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Quantitative Method
The Cuprous Iodide and Iodine Method
S.F. Yavorovskaya proposed a quantitative method based on the principle
described on the previous page in which silicagel is used in the place of filter
paper. The granular silicagel indicator is saturated with iodine and cuprous
iodide solutions.
Reagents, 1. Potassium iodide, c. p. 2. Sulfuric acid, water-free.
3. Sodium sulfite, c.p. 4. Nitric acid, c.p., 140sp.gr.. 5. Sulfuric
acid, c.p., 1.70 sp.gr. 6. Hydrochloric acid, c.p.-1.10 sp.gr. 7. Sili-
cagel granular, 1.5-2.0 mm.
Preparation of_the silicagel indicato_r_. Treat 100 g of the granular
silicagel successively with sulfuric and hydrochloric acids followed by -wash-
ing with distilled water. Dry and calcine. Place the silicagel into a porcelain
dish and add 150 ml of 10% solution of copper sulfate and 25 ml of 5% solution
of potassium iodide; leave stand for 20 min. and dry at 70° to complete re-
moval of moisture and of iodine vapor. Sift the granules to make them free-
flowing, and run into glass tubes 3 mm in diameter, 60-70 mm long until a
2 mm layer of the tapped—in powder is formed. Seal the tubes hermetically.
Dishes.
1. Beakers, glass, 50 and 100 ml capacity.
2. Filter paper.
3. Porcelain dishes.
4. Glass rods.
Analytical procedure. Immediately before the analysis cut open both
ends of the tube with the aid of a glass file and aspirate through it 1 li of the
air at the rate of 200 ml per min. For the quantitative determination of Hg
in the air prepare a standard color scale to correspond with different known
concentrations of Hg in the air at intervals of 0.0002 mg/li to cover one
range from O up to 0.0009 mg/li, and another standard series should range
from 0.001 to 0.003 mg/li at intervals of 0.001 mg/li. Prepare standards
as described in preceding chapters in connection with other substances. Make
final determination by comparing the color obtained by air aspiration with the
colors of first or second range standard scales.
Calculate results as described above. Results of the present method
diverge from the result of the N.G. Polezhaev and Plisetskaya methods by
about 0. 0009 mg/li.
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HYDROCYANIC ACID (HCN)
Hydrocyanic acid is a colorless fluid which has a characteristic odor of
bitter almonds. Mol. wt. of HCN is 27. 026, itssp.gr. is 0. 691 and its b. p.
is 26. 5°. HCN is easily soluble in water, in alcohol, and in ether. Its
sp. gr. compared with air is 0. 930.
Toxicology
HCN in the liquid or vapor form is one .of the most potent poisons.
Symptoms of poisoning following prolonged inhalation of HCN appear even at
concentrations as low as 0. 05 mg/li. HCN blocks tissue respiration creat-
ing a condition of extreme hypoxia resulting in tissue asphyxiation. Inhala-
tion of HCN vapor for 1 hr in 0.1 mg/li concentration elicits a sensation of
a bitter metallic taste, burning in the mouth, pressure over the chest, head-
ache, vertigo, general weakness, nausea and vomiting. In graver cases
there appear symptoms of general excitability, dyspnea, pupillary dilatation,
loss of consciousness, and spastic convulsions. The limit of allowable HCN
concentration in the air has been set officially at 0. 0003 mg/li.
Qualitative Reactions
The Indicator Method
Saturate the filter,paper with a solution of ferric sulfate; in the presence
of HCN the indicator turns yellowish brown. The reaction is as follows:
FeSO44-2HCN->Fe(CN)2
Reagents. 1. Ferric sulfate, 10% solution. 2. Potassium carbonate,
20% solution.
Place the filter paper in the 10% solution of FeSO4 for 5 min. , dry,
impregnate for 15 min. with a 20% solution of the potassium carbonate and
dry at room temperature, followed by final drying in vacuum; cut the paper
into strips 3.5x2.5 cm.
Analytical procedure. Place the indicator filter paper strips at points
of air analysis. In the presence of HCN the indicator paper will turn yellow-
ish-brown. For details of the procedure and quantitative estimation see
page 30.
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The Congo Red and Silver Nitrate Filter Paper Method
Saturate the filter paper with a solution of congo red and silver nitrate
and dry. Appearance of a blue color indicates the presence of HCN in the
air. The reaction is as follows:
HCN + AgNO3-»AgCN
Dry the filter paper strips at room temperature.
Reagents. 1. Congo red, 0.05% solution. 2. Silver nitrate, 2%
solution.
Analytical procedure. Aspirate the tested air through the filter paper
by a device illustrated in Fig. 5 as shown on page 1, and evaluate the
results as described on page 30. Alkaline and acid gases interfere with
the reaction.
The Methyl Orange and Mercurous Chloride Method
This qualitative method for the determination of HCN was described by
Cherrard; it is based on a change in the methyl orange color in the presence
of mercurous chloride. The reaction proceeds as follows:
The freed HC1 changes the original methyl orange color to a rose color.
Reagents. 1. Mercuric chloride, 0.5% solution. 2. Methyl orange,
0. 24% aqueous solution.
Mix 20 ml of solution 1 with 10 ml of solution 2 and add 1 ml of glycerol.
Dip the filter paper into this solution; allow excess to drip off and dry in
neutral air. Store in tightly stoppered orange colored glass vials.
Analytical procedure. Place the paper at point of air investigation for
2 miii] In the presence of HCN the original orange color will turn rose or
red. The presence in the air of acid vapors interferes with the determina-
tion.
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The Method of Filter Paper Saturated with Benzene Nitroderivatives
Johnson described several methods for the detection of HCN in the air
in which the basic solution consisted of 10% potassium carbonate. The filter
paper is saturated with this solution and dried in the air and is then dipped
into one of the following solutions:
Reagents. 1. 4-nitrobenzaldehyde, 5% solution in acetone.
2. 4-4' dinitrobenzene, .5% solution in acetone.
3. 4-nitrobenzene, 5% solution in acetone.
4. 2, 5-diphemyl or 3, 4-bis -p-nitrophenylfurane, 5%
solution in acetone.
5. Potassium carbonate, 10% aqueous solution.
6. Acetone, purified.
Analytical procedure. Before making the actual determination moisten
the indicator filter paper in acetone, since the sensitivity of the test depends
upon the presence of acetone; in the dry state the paper sensitivity is con-
siderably lower. The filter paper can also be. moistened with pyridine,
acetylacetone, n-butylphosphate, or dimethoxytetraethyleneglycole. In the
presence of HCN in the air tests made with solutions 1 and 2 should be
regarded as positive if the light yellow ccrlo-r changes to pu-rple; in- te'sts made
with reagent 3, the corresponding change in color will be from light yellow to
brownish red, while with reagent 4 the light yellow will change to violet
green.
Sensitivity of the reaction is high; the presence in the air of 0.01 mg of
HCN per li will effect a change in the indicator paper color.
Qualitative Determination
The Copper Acetate and Benzidine Filter Paper Method
This method, described by Sieverts, is based on the reaction taking
place between HCN and copper acetate in the presence of benzidine. The
copper acetate reacts with the HCN and is converted to cupric cyanide, which
reduces to cuprous cyanide as shown by the following reactions:
Cu(CH3COO)24-2HCN->Cu
2Cu(CN)j,+ H2O -o Cu2(CN)j + 2HCN + O.
The oxygen liberated by this reaction oxidizes the benzidine into benzidine
-72-
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blue as shown below.
\=NH4-H,0.
One molecule o£ oxidized benzidine combines with a nonoxldLzed to form a.
complex meriquinoid compound which is of a blue color. It takes about 3 to
30 sec. for this color to develop, depending upon the concentration of HCN
in the air.
Reagents. 1. Prepare the solution of copper acetate as follows: dissolve
3 g of copper acetate in. 100 ml of distilled water. 2. Prepare solution of
benzidine acetate as follows: dissolve 2-3 g of benzidine acetate in 100 ml of
hot (80°) distilled water. Cool and filter to clarity. The filtrate contains over
1% of benzidine acetate; it should be used only during the first two days after
its preparation.
Dishes.
1. Funnel, separatory, 200 ml.
2. Beakers, glass, 150-200 ml.
3. Cylinder graduate, 100 ml.
Analytical procedure. Mix 25 ml of the benzidine acetate solution with
2 ml of the copper acetate solution, mix well and dip filter paper into this
solution; dry and place into tightly stoppered test tube. For the determina-
tion of HCN in the air remove the paper from the test tube and expose to the
tested air.
Calculation of results. Note the time, in seconds, Lt took for the blue
color to attain highest degree of intensity. Estimate HCN concentration in
the air using the observed time interval in seconds as the basic factor.
Example. At 0. 0011 mg/lL HCINf concentration in the air a light blue
color will appear in 60 sec. , whereas at 0. Oil mg/li a dark blue color will
appear after 6 sec., and at a. concentration, range of 0.1L-1.1 mg/li the paper
will turn blue immediately. The reaction is not specific, since oxidizing
agents, if present in the air, produce the same color change.
The Phenolphthalin Method
This method is "based on the fact that cuprous salts are reduced in the
presence of HCN, accompanied by the liberation of active oxygen which
oxidizes the phenolphthalin to phenolphthalein. The reaction proceeds as
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illustrated in the determination of H3O3 as shown on page 27. In alkaline
medium this reaction produces a red color. Determination for the presence
of HCN in the air can be made by using filter paper satured with the follow-
ing reagent solutions.
Reagents. 1. Cupric or cuprous sulfate, 0.05% solution. . 2. Phenol-
phthalin solution which is prepared as follows:
Dissolve 0. 5 g of phenolphthalin in 30 ml of absolute alcohol; add dis-
tilled water to the point of appearance of a slight turbidity; then add 20 g of
NaOH. The solution turns a raspberry red. Add 2 g of powdered aluminum
or zinc, gradually mixing the solution until the color completely'drsappears," ~
then add 25 ml of COs-free water. Bring to a boil, cool, and filter.
Dishes. .
1. Cylinder graduate, 100 mi.
2. Beaker, 100 ml.
Analytical procedure. Saturate the filter paper at first with the 0.05%
solution of CuSO4, dry, moisten with the phenolphthalin solution prepared as
previously described and again, dry. Upon exposure to air containing HCN
the indicator paper, prepared as described, will acquire a red color. The
reaction is sufficiently sensitive to detect the presence in the air of one part
of HCN in 5 million parts of air, in other words, the sensitivity of the method
is 0.00024 mg/li. Compute results as outlined on page 15.
Modified Method for the Determination of Hydrocyanic Acid
The method for the quantitative determination, of hydrocyanic acid was
previously described by Nil. Fomicheva. It is a rapid indicator tube method.
In its principle this method is similar to the above described benzidine
method, differing from it in the preparation of the reagents and in the techno-
logical procedure. The method is "based on the fact that hydrocyanic acid
reacted with benzidine to form benzidineblue. Silicagel saturated with the
reagent and .sealed into glass tubes is tlie indicator carrier in this method.
Reagents. 1. Benzidine acetoacetate, 0.2% solution, prepared .by dis-
solving 0.2 g of basic benzidine in 100 ml of distilled water to which add
8 drops of 40% solution of acetic acid. 2. Copper acetate, 0.3% solution.
3. Silicagel, pure, granulated, 0.5-1 mm diameter.
Preparation of the indicator g_el and of the indicator tube. Moisten 2 g
of above specified silicagel with 1. 5 ml of a mixture containing equal
volumes of solutions 1 and 2 and Leave stand for 30 min. Evaporate excess
of liquid at low temperature and dry. Place the silicagel indicator into a
••••'. -74-
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glass tube 50-60 mm long and 5 mm in diameter. Place a 20 mm layer of
the silicagel indicator, insert cotton plugs at either end of the tube and seal
hermetically by fusing.
Dishes.
1. Porcelain dish, 15 cm in diameter.
2. Glass tubes, 50-60 mm long, 5 mm in diameter.
Analytical procedure. Cut open the indicator glass tube at both ends
with the aid of a glass file and aspirate 180 ml of air in 15-18 sec. using an
appropriate rubber suction bulb.
Calculation of results. The indicator color changes with time. This
must be taken into consideration. Final evaluation is made with the aid of a
standard color scale by a procedure severally described in previous para-
graphs. This procedure makes possible the detection of 0.0004-0.05 mg/li
of HCN.
NICKEL TETRACARBONYL [Ni(CO)4]
Nickel tetracarbonyl is a colorless fluid having a m. p. of 25°, b. p. of
42°; it is water insoluble, and does not react with dilute solutions of acids
or alkalies; it ignites in contact with concentrated sulfuric acid. A mixture
of nickel tetracarbonyl vapor with air is explosive.
Toxicology
Nickel tetracarbonyl is irritating to the respiratory tract; upon permea-
tion into the blood system it may cause general poisoning, affecting primar-
ily the nervous system; according to K.A. Armit the presence in the air of
nickel tetracarbonyl in concentration of 7 mg/li can cause vertigo, short-
ness of breath and headache, followed by a 12-18 hour occult period, after
which cardiac and respiratory symptoms again arise accompanied by liver
pain, acute dyspnea; cough and rise in temperature. This in turn may be
followed by delirium and convulsions. There is no officially adopted limit
of allowable [ Ni(CO)4Jconcentration in the air, but some foreign authors
proposed 0.007 mg/li.
Quantitative Determination
The Gold Chloride Method
Kobayasi proposed a method for the rapid determination of nickel tetra-
carbonyl in the air which is based on change in solution of gold chloride from
yellow to violet blue color in the presence of nickel tetracarbonyl.
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Reagents. 1. Gold chloride, 0. 5% solution. 2. Silicagel, granular,
0.25-0.35 mm diameter.
^rej)_a_ratiori_o_f_the indicator gowder and indicator tubes. Moisten 2 g of
the silicagel with 1.5 ml of^the gold chloride solution and desiccate; pour the
dry granular indicator into glass tubes to a 40-50 mm layer; insert cotton
plugs at either end and seal the tubes by fusing.
Equipment. . :
1. Porcelain dishes. :
- - 2. Gla&s—tubes,, .60-80 mm..long,,2 mm.wide.
3. Glass rods.
4.. Glass wool.
Analytical procedure. Aspirate 100-500 ml of the tested air through the
tube at the rate of 1 ml per sec. Record and compute results by the linear-
colorimetric method. When necessary 1-2 li of the air can be aspirated
through the tube which will make possible to determine 3 parts per million
of LNi(CO)4Jin the air. Carbon monoxide and acetylene interfere with the
reaction.
Calculation of results. This is done with the aid of a previously con-
structed curve described in pages 3 and 4.
CARBON DIOXIDE (COS)
Carbon dioxide is a colorless and odorless gas; its mol.w.t. is 440.1;
1 ml of the gas at O° and 760 mm of mercury weighs 1. 9768 mg; its sp.gr. in
relation to air is 1.5291, and its molar volume is 22.26. Carbon dioxide is
easily soluble in water; at 15° water will absorb an equal volume of CO2.
Toxicology .
CO2 acts on the nervous system producing a narcotic effect, especially
in cases of hypoxia; it is slightly irritative to tissues. In the presence of 16%
of oxygen the organism can tolerate a 5% concentration of CO3; above 8% it
causes rapid respiration, irritation of the mucous membranes of the respira-
tory tract, cough, a sense of pressure in the head, headache, and occasion-
ally nausea. The range of limits of allowable CO3 concentrations is between
0. 1 and 0. 5%, depending upon the duration of exposure to CO3 inhalation.
-76-
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Qualitative Reactions
The Bariurn Hydroxide Method
Aspiration of air containing COa through a solution of barium hydroxide
produces a precipitate of barium carbonate.
Reagents. 1. Barium hydroxide, 0. 05 N solution.
Analytical procedure. Pour the barium hydroxide into an absorber,
as is shov.'n in Figure 12 with the aid of a burette as shown in Figure 13.
burette and the bottle shown in Fig3. 12 and 13 are protected against the
entrance of COa from the air by means of calcium chloride tubes. Run the
such
The
Figure 12
FigujeJ.3
FlS. 13. 30TTLE AHO SU3ETTE FOS
KEEPI.18 ANO 3EMOVIMG MEASURE*
AMOUNTS OF 1ARIUM HYOHOXI8E.
barium hydroxide solution into the absorber so as to prevent it from coming
into contact with COa. This is accomplished by a procedure well known to
experienced air analysts and need not be described in detail. After filling
the absoi-ber tube with the barium hydroxide solution, aspirate 200 ml of the
tested air through it.
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Quantitative Determination
The Thymolphthalein Method
Kobayasi described a method for the determination of carbon dioxide
.which was based on the fact that in the presence of CO2 thymolphthalein
changed from blue to yellowish-orange. In this case oxide of aluminum is
used as the indicator carrier; results are evaluated by the linear colori-
metric method.
Reagents. 1. 1% alcohol solution of thymolphthalein. 2. Ethyl alcohol.
3. Sodium~ hyd-rxjxidev-Or I M solution-. 4-. Powdered a4iM^iaam.-oxide-.----; -
Preparation of the indicator tubes. Dissolve.0. 5 g of thymolphthalein in
50 ml of ethyl alcohol and .add one drop at a time of 0.1 N NaOH solution to
the appearance of a well defined blue color. .Moisten 1 g of the aluminum
oxide powder with 0.1 ml of the thymolphthalein solution. Mix well with a
glass rod; this must be done in a CO2-free atmosphere to a free-flowing
consistency; place the powdered indicator into glass tubes of 2-3 mm diame-
ter to a layer 3-5 mm; insert cotton plugs at each end, and seal the tube
hermetically.
Dishes and other materials. •...'•'
1. A 25 ml pipette, graduated into 0.1 ml.
2. Chemical beakers, 50 and 100 ml,
3. Porcelain dish.
4. Glass rod.
5. Non-hygroscopic cotton.
6. Glass tubes, 2-3 mm in diameter, 60-80 mm long.
Analytical procedure. Aspirate 100 ml of the tested air through the tube
over a period of 20 sec. using a device shown in Figure 6, page -7.
Calculation of results. Use a graduated curve in combination with the
linear colorimetric method as described on page 23. By this method it is
possible to determine CO2 concentrations in the air in the range of 0.5-0.6%.
The Hydrazine Hydrate and Fuchsin Method
According to M.T. Lukina and G.L. Borodina a mixed solution prepared
from hydrazine hydrate and basic fuchsin is colorless; however, when air
containing carbon dioxide is passed through it the fuchsin regains its
original color. ,
\
Reagents. 1, Nitric acid, concentrated. 2. Ethyl alcohol. 3. Fuchsin,
basicT T. rTyvd;r^zine hydrate, sp. gr. 1. 03 (COST 5832-51). 5. Silicagel,
granular 0.1SrO.,25 mm diameter.
-78-
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-_raJ;iqn _of_the^silicagel,_ the_in^iicatqr p_owder, and the Indicator
tub_e.s_. Prepare the powder by grinding technical silicageL and sifting it
through a proper gauge sieve. Treat the powder with concentrated HNO3.
Completely remove the nitric acid by washing with distilled water; air dry
and desiccate at 800°; pass through the proper gauge sieve to make sure that
the particle diameter range is within 0.15-O.Z5 mm. Prepare the indicator
powder as follows: add one drop at a time of 10 volumes of 0.1% alcoholic
solution of basic fuchsin; add 3 volumes of concentrated hydrazine hydrate of
1. 03 sp. gr. ; filter.and add to the filtrate one volume of hydrazdne; moisten
the silicagel powder with this solution at the rate of 1 ml per 1 g of the
silicagel. Spread the moist layer to a thickness of 0.5 cm over the filter
paper; dry first with filter paper and then in a drying oven at 37° for 3-5 min.
with constant stirring; distribute the dry powder into ampules; seal the
ampules immediately by fusing. The indicator powder thus prepared will
keep for 2 months. Three days before making the air analysis pour the indi-
cator powder into glass tubes of 2. 5-2. 8 mm diameter and 90 mm long,
taking care that the powder did not come in contact with the atmospheric air.
Place cotton plugs at each end of the tube, cover with aluminum or rubber
caps and seal with sealing wax. Prepare the standard scale by passing
through a series of indicator tubes air containing known concentrations of COg
Dishes and other materials.
1. 500 ml, glass beakers.
2. Glass rod.
3. Glass tubes, 90 mm long, 2.5-2.8 mm diameter.
4. Cotton.
5. Funnel.
6. Filter pape r.
7. Aluminum foil and sealing wax.
Analytical procedure. Aspirate the tested air through the tubes by using
devices shown in Figures 3 and 4, pp. 6 and 7; or use a micro aspirator, such
as is depicted in Figure 2, page 6.
Prepare standard graduated curves on the basis of colors obtained with
known CO3 concentrations. Such curves are usually prepared on the basis of
50, 125 and 175 ml of air. Best results are obtained with aspiration .of 125 ml
of air which enables CO2 concentration determinations in the range of
0. 5-9. 0%. Experience indicated that unsaturated hydrocarbons, gasoline
•vapors, small quantities of hydrogen sulfide had no effect 011 color changes
of the indicator material contained in the tubes. However, at hydrogen sul-
fide concentrations of 0. 3 mg/li and higher the indicator color fades, thereby
causing difficulty in the CO3 determinations.
Calculation of results. See page 23.
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RAPID METHODS FOR THE DETERMINATION OF
- ORGANIC SUBSTANCES IN THE AIR
. FORMALDEHYDE (HCOH)
Formaldehyde is a colorless gas easily soluble in water and has a sharp
odor; the mol. wt. of HCOH is 30. 02; its sp. gr. in relation to air at 20° is
0. 815. A 33% solution of HCOH in water is called formalin (COST 1625-45).
Liquefaction point-of-HGOH- ts -92° and-b-. p-. is -19.-2-0. - - - - -
Toxicology
Like all aldehydes HCOH irritates the mucosa of the eyes and of the
respiratory tract. It causes nasal catarrh, bronchitis, general weakness.
intestinal disturbance and kidney damage. Mucous membrane irritation
begins with 0.025 mg/li concentration. The limit of allowable HCOH con-
centration was officially set at 0.01 mg/li.
Qualitative Reactions
The Hydroxylamine Hydrochloride and Potassium Ferrocyanide Method
This test is based on thymol blue changing from yellow to red in the
presence of hydrochloric acid, which is liberated in the course of reaction
between hydroxylamine hydrochloride and the aldehyde, resulting in the
formation of oxine or 8-hydroxyquinoline.
Reagents. 1. Thymol blue, 0. 05% alcoholic solution. 2. Silicagel,
granular, 0. 25-0. 35 mm diameter. 3. Hydroxylamine hydrochloride,
1% solution.
Analytical procedure. Treat 1 g of the specified silicagel with a 1%
hydroxylamine hydrochloride solution, adjusted to neutral reaction with
thymol blue as the indicator; dry to an easily flowing powder; add 0.05%
of alcoholic solution of thymol blue; mix thoroughly with a glass rod, and
again dry to a free-flowing state; store the prepared indicator powder in
sealed ampules. In performing air analysis pour the powdered silicagel
indicator into glass tubes 60 mm long and 1. 5-2. 5 mm in diameter to a
column of 3-5 mm high; insert cotton plugs at each end of the tube; aspirate
the tested air through the tube as shown in Figures 3 and 4, pages 6 and 7.
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Quantitative Determination
The Phenylhydrazine Hydrochloride Method
This rapid quantitative method was proposed by V. P. Fedbtov. It is an
adequately sensitive and easily performed method and is recommended for
use under field conditions, especially where a large number of tests may be
required. The method is based on the reaction between formaldehyde and
phenylhydrazine hydrochloride which forms phenylhydrazine according to
the following reactions.
O 1
"
The phenylhydrazine reacts with the potassium ferrocyanide in hydrochloric
acid medium producing a brilliant red color.
Reagents. 1. Phenylhydrazine hydrochloride. 2. Methyl alcohol,
redistilled. 3. Potassium ferrocyanide. 4. Hydrochloric acid, 1.12 sp.gr.
5. Formaldehyde, 40 or 33%. 6. Silicagel.
Preparation pf_the indicator gel and of the tubes. Prepare the indicator
mass as follows: take granular silicagel of 0.25-0.6 mm diameter and
saturate with 0. 3% of freshly prepared alcoholic solution of phenylhydrazine
hydrochloride at the ratio of 0.5 ml of the solution for. each 0.5 g of the
silicagel, mix well, dry thoroughly, and pour into glass tubes of 4 mm
diameter and 50-60 mm long. Height of the silicagel indicator column
should be not less than 10 mm.
Dishes and other accessories.
1. Glass tubes 3. 5-4. 0 mm inside diameter and 50-60 mm long.
2. Cotton.
3. Glass rod.
4. Porcelain dishes .
5. Cylinders, 100 ml divided into 0.5 and 1 ml..
Analytical procedure. Aspirate 1 li.of the tested air through the indicator
tube preared as above described over a period of 2. 5 min. With the aid of a
vertically inserted tube and a thin pipette run in the following oxidizing solu-
tion: 0. 04 g of potassium ferrocyanide dissolved in 1 ml of hydrochloric
acid of 1.12 sp. gr. Exactly the same amount of the acid must be used in all
tests. In the presence of formaldyde in the air the indicator will turn red;
the intensity of the color will be proportional to the formaldehyde concentra-
tion in the air.
-81-
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Calculation of results. Evaluate results colorimetrically by comparing
the color intensity of the indicator with a standard color scale prepared as
previously described on page 15 or other similar methods. The solution
used in saturating the indicator carrier must be prepared anew every 3-4
days. The sensitivity of the reaction is 0.0002 mg/li of HCOH. The method
is adequately specific. The presence in the air of acetaldehyde, acrolein,
furfural, acetone,, phenol, hydrogen sulfide, and SO3 in concentrations up to
0.1 mg/li had no effect on the results.
ETHYL ALCOHOL VAPOR (C3H6OH)
Ethyl alcohol is a colorless liquid having a specific odor; its m.ol. wt. is
46.07; 1 ml of ethylol in the vapor state and under normal temperature and
.pressure weighs 2. 043; sp. gr. of alcohol in relation to air is 1. 580 and its
mol.vol. is 22.55. The b.p. of ethylol is 78.3°. Ethylol is soluble in water
and in ether.
Toxicology
Alcohol possesses narcotic properties appearing at first as a state of
stimulation followed by a state of depression of the central nervous system.
Chronic inhalation of ethylol vapor results in liver damage. The limit of
allowable alcohol vapor concentration in the air has been adopted at 1. 0 mg/li.
Qualitative Reaction
The Chromic Anhydride Method
This rapid method for the determination of ethylol vapor in exhaled air
was developed by L.A. Mokhov and.I. P. Shiiikarenko. The test was origin-
ally intended for the detection of alcohol in exhaled air of drunken persons. .
However, it can be conveniently used for the detection of ethylol vapor in the
air of production and manufacturing premises; it yields a satisfactory approx-
imation of the concentration of this vapor in the air of indoor premises. The
method is based on the general reducing property of alcohols. Chromic
anhydride is used as the oxidizing reagent by which the degree of reduction
can be judged. The hexavalent molecule of Cr"O3 becomes converted into
trivalent Cr2O3 changing the original orange-yellow color to green. This
reaction proceeds according to the folio-wing equation.
4Cr03+3CH,CHapH-2CraO,+3CH,COOH+3H,0.
Reagents. 1. Chromic anhydride, c. p. 2. Sulfuric acid, sp.gr. 1.84.
3. Silicagel, granular, purified, )0.25-0.3 mm diameter.
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P_re_p_aration of_the indicator mas_s. Saturate 4. 7 g of granular silicagel
calcined at 550° with 2 ml of 3% chromic anhydride containing 0. 3 ml of con-
centrated sulfuric acid; place the indicator into a glass tube to a column
3-4 mm long; insert cotton plugs at each end of the silicagel column and
seal the tubes by fusing.
Analytical procedure. Cut the indicator tube open at both ends and
aspirate through it 500-600 ml of air. Change of indicator color from orange
yellow to green is positive indication of the presence of alcohol vapor in the'
air.
Quantitative Determination
The method is based on the oxidation of e'thylol by a solution of potassium
permanganate in the presence of sulfuric acid. Excess of potassium perman-
ganate is determined titrimetrically. The method is not specific. Other
alcohols and ether interfere with the determination.
Reagents; 1. Potassium permanganate, 0.05 N and 0.02 N solutions.
2. Sodium oxalate 0.05 N solution. 3. Sulfuric acid, 5 N solution.
4. Water, double distilled.
Apparatus and dishes.
1. Aspirators of 4-5 li capacity, two.
2. Aspirators, Zaitsev, six.
3. Pipettes, 25 ml with ground-to-fit stopcocks and drawnout tips.
4. Microburette, 10 ml.
5. Pipettes, 2, 10 ml capacity.
6. Four conical glass flasks with ground-to-fit glass stoppers.
7. Two 500 ml volumetric flasks.
8. Three reagent bottles.
9. Waterbath.
Analytical procedure. Take duplicate samples for each determination;
aspirate 10 li of the air at the rate of 30 li/hr. through 3 Zaitsev aspirators,
each containing 5 ml of distilled water; aspirate 10 li of air through each
aspirator at the rate of 30 li/hr.; upon completion of the aspiration pour the
content of the aspirators into a 100 ml Erlenmeyer flask equipped with a
ground-to-fit stopper. Do not rinse the aspirator. Place into the Erlen-
meyer flask 7 ml of 0. 05 N solution of the permanganate and 13 ml of
5 N H^SO4. Stopper the Erlenmeyer flask, shake well and place into a dark
room for 30 min. Simultaneously set up a control test with distilled water;
at the end of 30 minutes add 10 ml of 0.05 N sodium .oxalate solution to the
experimental and control flasks, heat over a waterbath at 75-85°, and while
hot titrate excess of oxalate with 0.02 N solution of KMnO4 until a pale rose
color develops.
-83-
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Compute results with the aid of the following formula.
V - (7,5+Ui)-0.0153
in which C represents mg/li of ethylol vapor in the air;
V represents ml of 0.2 N KMnO4 solution consumed, by
the titration of the air sample;
Vj • represents ml of 0.02 N KMnO4 solution consumed by
the titration of the control test;
V2 represents li of air aspirated and reduced to normal •
temperature and pressure;
0.0153 is a coefficient (l. 0 ml of 0.02 N solution of KMnO4 is
the equivalent of 0.153 mg of ethylol);
7. 5 3 ml of 0.05 N solution of the oxalate is the equivalent
of 7.5 ml of 0.02 N solution of KMnO4.
LIQUID FUEL VAPOR
Gasoline, varnish, kerosene (white spirit), ligroin, ordinary kerosene,
etc. A mixture of these hydrocarbon vapors is frequently found in indoor air
of certain manufacturing and processing establishments. The sanitary-
chemical analyst will frequently encounter, the following fractions of crude
oil: petrolic ether of low and high boiling points, gasoline, varnish, kerosene,
ligroin and ordinary kerosene. Some properties of these hydrocarbons are
listed in Table 6 below.
PROPERTIES OF CRUDE OIL PRODUCTS
HYDROCARBON
NAME
PETROLIC ETHER:
Lou BOILING.,
HIGH BOILING.
AVIATION
BENZINES
GBOZHEMSK....
BAKI NSK.o.. oo
BEMZIHE
"GALOSHA"...
LACQUER
GASOLINES
(WHITE SPIRIT
KEROSENE. o...
SP. GR.
0.64
0.66
0.7
0 79 S
V, 1 i"J
0.745
) 0.794
ft 7Q^
f, / yJ
0.8-0.837
B.Po
30-50°
45-70°
60-120°
80-120°
140-190°
1 \C\ O'W
150-270°
FLASH
POINT
- -20°
—
_
25"
—
33°
•4-7 4-9°
+21 -+28°.
o
35 •<
.ul to
<£ r
0 E
a.
> —
331
139
8
3
56
_
o/v
—
UJ
1 Ul «
ft. Q- ••
X =) <
UJ t-
X X
u. — 1-
o j: —
3
13.
1.1-3.8
—
1,2-7.0
19 51
2.6-4,9
' _
2.0-3.0
-84-
-------
Vapors of the above fuel hydrocarbons are sparsely soluble in water,
easily soluble in glacial acetic acid, in ether and chloroform, and poorly
soluble in alcohol. Vapors of liquid fuels are 3-3. 5 times as heavy as air;
petrolic ether vapor is twice as heavy as air.
Toxicology
No reports have been found in the literature which described the toxic
action of individual liquid fuels,, therefore, general characteristics of the
Liquid fuel group as a whole -will be described briefly. The toxic properties
of the above mentioned vapors are basically due to the presence in such
substances of higher fractions of crude oil, the inhalatiorr of whi eh-cause s-
ir-ritation of the larynx, of the respiratory passages, of the conjunctiva,
headache, vertigo and general weakness. Prolonged inhalation of air con-
taining high concentrations of volatile hydrocarbons occasionally results in
pulmolary inflamation. The presence in the air of hydrogen sulfide, espe-
cially in the case of sulfur-rich crude oils, enhances the toxic properties of
hydrocarbon vapors. The limit of allowable concentration of the enumerated
hydrocarbons in the air -was officially set at 0. 3 mg/li.
Qualitative Determination
Linear Colorimetric Determination of Gasoline Vapor in the Air
T. N. Kozlyaeva and I.G. Vorokhobin developed a method for the quali-
tative and quantitative determination of gasoline in the air based on the
development of a light brown color by passing the gasoline vapor through an
appropriate indicator tube.
Reagents. 1. Potassium periodate, c.p. 2. Sulfuric acid, sp.gr. 1.84.
3. Granular silicagel of 0. 16-0. 25 mm in diameter.
P_r_e_p_a_ra_tion_o_f_t_he_ silicageL_and of fche_i_ndica_tor_tube_. Place 2. 5 g of the
potassium periodate (KIO=) into a glass stopper and mix again until the KIO3
completely dissolves; then place several grams of the above described
silicagel; mix thoroughly with a glass rod, then spread to a layer of 8-10 mm
and dry in a drying oven at 200-210°; stir frequently during drying. The dry-
ing oven must be placed inside of an exhaust hood to remove vapors of acetic
acid generated during the drying of the prepared mixture. Place the pre-
pared silicagel indicator into a glass desiccator equipped with a ground-to-
fit cover containing sulfuric acid, or pour the silica gel into glass ampules
and seal.
Accessories.
1. Porcelain dish.
2. Glass rods.
-85-
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3. Glass flask with ground-to-fit stopper.
4. Glass tubes 60 mm long and 1.5-2.0 mm inside diameter.
5. Drying chamber.
• 6. Apparatus for air aspiration such as illustrated in Fig. 1, page 5.
Analytical procedure. As the aspirated air passes through the indicator
tube part of the silicagel indicator will acquire a light brown color if the air
contains gasoline vapor.
Calculation of results. Results are evaluated by the linear colorimetric
method with the aid of a standard curve or table as previously described for
other vapors". ...... ....
The standard scale is prepared on the basis of 175 ml of aspirated air
c.ontaining gasoline vapor in the range of 0.2-5.0 mg/li with intermediate
steps of 0.2 mg/li. If the gasoline vapor in the air is suspected to be at
concentrations up to 30 mg/li, then only 50 ml of the air is to be aspirated
through the tube. Determination should be made at a temperature range of
2-35°. Determination errors in the lower concentrations will range between
10 and 15%, and at higher concentrations 2-5%. The authors of the test admit
that the sensitivity of the method proved inadequate at lower gasoline vapor
concentrations in the air. However, the method is highly valuable in the
determination of explosive concentrations of gasoline in the air, which is of
considerable practical importance.
The Chromic Anhydride Method
The method proposed by A. V. Demidov, L.A. Mokhov, and B. E.
Malyshkin is more sensitive and more accurate than the one previously
described. In this method chromic anhydride is used in the preparation of
the indicator, as described by L.A. Mokhov and I. P. Shinkarenoko on page
82.
Reagents. See page 82.
Accessories.
1. Porcelain dish, 10-12 cm in diameter.
2. 100 ml glass cylinder graduate.
3. Five and 1 ml gradual pipettes.
4. Glass tubes, 60 mm long, 3 mm inside diameten
5. Glass wool.
6. Apparatus for air aspiration through the indicator tube as illustrated
by Fig. 1, page 5, or by Fig. 2, p. 6.
Analytical' procedure. Aspirate a measured amount of the tested air
through the. indicator tube until a reddish brown ring appears.
: " "^ ,. '
•-8-6"-'
-------
Calculation of results. Evaluate results with, the aid of a standard
curve, the abscissa divisions of which represent volumes of air and the
ordinate divisions represent liquid fuel vapor concentrations. The curve
should be constructed preferably on .the basis of gasoline, petrolic ether
and similar hydrocarbons. The sensitivity of the method is 0. OZ mg/li,
and the error is ±5%.
Products of Thermic Oxidation of Mineral Lubricating Oil
When mineral lubricating oil is dropped accidentally upon a super-
heated surface, thermic breakdown of the oil takes place due primarily to
oxidation. This occurs usually when lubricating oil is heated up to 150-200°
or higher. The limit of allowable concentration of thermically decomposed
vapor in the air was officially set at 0.02 mg/li.
Toxicology
Thermic decomposition of mineral lubricating oils liberates into the air
aldehydes, ketones, alcohols, volatile acids, hydrogen sulfide, oil aerosols,
etc.; the mixture, or complex, of the above mentioned vapors causes irrita-
tion of the mucous membrane,and in higher concentration may act as a
poisonous complex.
Quantitative Determination
Determination of individual components of the above described vapor
complex presents many difficulties and is time consuming; therefore, for
practical purposes, the total complex of thermic mineral oil oxidation
products is determined at present. I.F. Turov developed a luminescent
method for the determination of the above described vapor complex in the
air. Determination of dispersed lubricating oil aerosol in the air is made
by the method of M. V. Alekseeva and Ts. I. Gol'dina.
For the luminescent determination air samples are collected in glass
gas pipettes; the vapors contained in the air are then dissolved in different
organic solvents and their concentration determined by the ultra violet
spectral absorption method.
The Indicator Tubes Luminescent Method
R. V. Adamov developed a method by which mineral oil aerosols can be
determined quantitatively in a short time. The air containing the oil aerosol
is aspirated through an indicator tube containing pure washed silicagel in a
known volume. The indicator tube is then exposed to ultra violet illumina-
tion. In the presence of mineral oil aerosols luminescence will appear, the
intensity of which is proportional to the amount of oil aerosol adsorbed by
-87-
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the silicagel, that is, to the aerosol concentration in the air.
Reagents. Silicagel, pure, granular of 0,06-0.01 mm in diameter.
2. Mineral oil,
Apparatus and dishes. •
1. A 100 li capacity hermetic container having two perforations or holes,
one on the side and another in the lid of the. container. Rubber stoppers with
central perforations are inserted into these holes. A glass tube is inserted
through the stopper plugging the container side hole; a proper diameter rubber
tubing is attached to the glass tubing. for the air sample- inflow; a ca-refu-11-y ------
calibrated glass pipette is inserted through the stopper plugging the hole in
the container lid. A metallic electrically heated plate is suspended inside the
container directly below the stopper protruding end of the pipette. The degree
to which the suspended plate is heated is controled and recorded by a pyro-
meter "built into the electrically heated plate. A small electric fan is
installed in the chamber which circulates the air and brings about an even
distribution of the products of thermic oil oxidation throughout the hermetic
container.
2. Aspirator for air suction from the above described chamber.
3. Glass tubes, 80 mm long, 3 mm inside diameter.
4. Apparatus for luminescent analysis consisting of a chamber with a
horizontal partition and an opening through which a light filter is inserted for
the absorption of all light rays with the exception of the ultra violet of 360 mpt
wave length. A quartz lamp is installed above the filter. Air samples which
develop a luminescence are examined with the aid of the light filter.
pf_s_tandajd_tub_e_s_. Prepare a series of standards for the
quantitative determination of thermal mineral oil oxidation products as
follows: prepare the tube, fill it with the silicagel and compress the silicagel
layer by pushing in cotton plugs at each end of the tube. Make different con-
centrations of the mineral oil thermic oxidation products in the chamber
described under 1 as follows: fill the graduated pipette with the mineral oil
up to the zero mark. Heat the metal plate to 200-400°, preferably maintain-
ing a uniform temperature. Run out 10 mg of the oil from the graduated
pipette, or a volume of the oil equivalent to 10 mg. After the oil has com-
pletely volatilized from the hot plate start the fan for about 30-40 sec.
Connect the indicator tube to the rubber tube inserted into the side opening of
the container as described in 1; aspirate the air contained in the chamber
through the indicator tube in a volume equivalent to 0. 01 mg of the volatilized
oil. Compute according to the following formula:
_ Ax. 100, 000
P
in which V represents ml of aspirated air;
A represents mg of the thermic oxidation products;
P represents mg of oil used in the thermic oxidation.
-88-
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Seal the tube by fusing after the air has been aspirated through it, cover
with sealing wax and keep in a warm place. Prepare a series of standard
tubes as above described representing the following amounts of products of
thermal oil oxidation: 0.00, 0.02, 0.04, 0.06, 0.08, O.lOmg, etc. to a
total of 10 or 12 tubes; use a series of other steps, if found more expedient.
Analytical procedure. Aspirate 1,000 ml of the air to be tested through
the indicator tube containing the silicagel.
Calculation of results. Evaluate results by comparing intensity of
luminescence of the experimental tubes with those of the standard. The
method sensitivity is 0.01 mg/li and its accuracy is 0. 01 mg. The most
difficult part in this procedure is the preparation of the standard series.
The actual determination is very simple.
PHOSGENE (COC13)
Phosgene is a gas which easily condenses into a liquid having a sp.gr.
of 1. 411 at 4°, and a b. p. of 8. 2°. It is easily soluble in benzene and in toluol.
Its mol. wt. is 98. 924; 1. ml of the liquid weighs 4. 531 g at normal tempera-
ture and pressure. Its mol. vol. is 21.833.
Toxicology
Phosgene has a comparatively slight effect on the upper respiratory
passages affecting mostly the finer bronchi and the lungs, slowing down the
pulmonary blood circulation and causing toxic pulmonary edema. Toxic
symptoms of COC1S are vertigo, headaches, general weakness, pressure on
the chest, cough, labored breathing, palpitation of the heart, nausea and
vomiting. There is a preliminary 8-10 hour period of occult intoxication
during which no symptoms of poisoning are in evidence externally. Death
usually occurs as the result of pulmonary edema. The limit of allowable
COClg concentration in the air was set at 0. 0005 mg/li.
Qualitative Reaction
The Diphenylamine and P-diethylaminobenzaldehyde Method
In 1939 English investigators proposed a highly sensitive and simple
method for the determination of COC13 in the air based on the reaction
between diphenylamine LCCgHgJgNHj and P-diethylaminobenzaldehyde
(C2H5)aNC6H4CHO; depending upon the phosgene concentration in the air the
reaction paper acquires the following colors: with COC12 concentration of
4.4 mg/li - orange brown; with 0.022 mg/li - bright lemon; and with
0.0044 mg/li - of the phosgene the developed color is a light yellow.
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Reagents. 1. Di.phenylamine, crystalline. 2. P-diethylaminobenzalde-
hyde, crystal. 3. Methyl alcohol, c.p.
Prepa_ration _of_the_indic_aj:or_£a£e_r. Dissolve 5 g of the pure P-diethyl-
aminobenzaldehyde and 5 g of the diphenylamine in 100 ml of 98% ethyl or
methyl alcohol. After the reagents completely dissolve shake the bottle to
mix the solution well, and saturate strips of filter paper by dipping them into
the alcoholic solution; dry and store in a dark glass bottle.
Analytical procedure. The test is not specific, since chlorine and hydro-
chloride gases interfere with the reaction; it is, therefore, necessary to ab-
sorb- aity- chloF-tne O^E- hy-Aro-chlnride .ga-S.es. pre.se.nt-in the. aLr. hef.ore. as.pLrating^
the air through the in dicator tube containing the paper. This is done by
.passing the air first through a Petri or Polezhaev absorber containing a solu-
tion of-50 g of sodium thiosulfate .and. 20 g of c.p. sodium iodate in 40 ml of.
warm water. The air can also be collected with the aid of a rubber bulb of
100 or 200 ml capacity and from it forced through the absorber and the
indicator tube. Other methods for the preliminary absorption of the Cl or
HC1 can be used if desired. The method is a qualitative one, but will detect
phosgene in the air in 0. 004 mg/li concentration.
The 1, 3, 6—nitrozediethylaminopbenol and P-dimethylaminophenol Method
Prepare a. solution of 0. 3 g of 1, 3, 6-nitrozodiethylaminophenol and 0. 25
of P-dimethylaminophenol in 100 ml of benzene; dip filter paper into it and
dry. In the presence of phosgene in the air the filter paper will change from
yellowish brown to green. This method was originally proposed by L. Z.
Soborovskii and G. Yu Epshtein.
Reagents. 1. 1, 3,6-nitrozodiethylaminophenol, crystalline.
2. P-dimethylaminophenol, crystalline. 3. Benzene, c.p.
Analytical procedure. Saturate the paper with the benzene solution of
the reagents, dry at room temperature, and place where the air is to be
tested. Appearance of a green color indicates the presence of phosgene in
the air.
Quantitative Determination
iodometric Method
In the presence of phosgene iodine is liberated from sodium iodide. The
amount of liberated iodine is determined by titration with sodium thiosulfate.
The amount of standard sodium thiosulfate used in the titration of the free
iodine is proportional to the amount of phosgene present in the air.
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Reagents. 1. Sodium iodide, 2. 5% solution. 2. Sodium thiosulf ate
(hyposulfite), 0. 01 N solution. 3. Potassium periodate, c.p. 4. Starch,
soluble, 1% solution. 5. Acetone, redistilled. 6. Sulfuric acid, 1:5 solution.
7. Potassium iodate, crystalline.
TAtion j3J'J^_e_sodium_thi_o_s_ulfate_ solution. Dissolve 25 g of sodium
thiosulfate in 1 li of distilled boiled and cooled water which will make approx-
imately a 0.1 N solution of NagSgC^. Determine the exact concentration as
follows: weigh out exactly 3. 567 g of desiccated chemically pure potassium
iodate, using an analytical balance, and dissolve in 1 li of distilled water
which should make a 0.1 N solution of .the reagent. Place 10 ml of this solu-
tion into a clean glass beaker and add 25 ml of distilled water, 10 ml of the
1:5 sulfuric acid solution and 0. 5 g of chemically pure potassium iodide; mix
and titrate the liberated iodine with the standard sodium thiosulfate solution
using starch as the indicator. If the titration consumed less than 10 ml of the
standard tliiusulfate that would indicate that the prepared solution was stronger
than 0.1 N and must be adjusted further. Accordingly, it becomes necessary
to compute just how much water must be added to bring the concentration to
exactly 0.1 N. For example, assume that the titration consumed 9.2 ml of
the standard Na^^g, then another 0. 8 ml of water must be added for each
9. 2 ml of the total volume of, say, 500 ml; hence
500-0.8 ., ._
•"92 -=43.47 of water
After the 43.47 ml of water has been added the prepared solution is check-
titrated as before. If the first titration consumed more than 10 ml of the
standard thiosulfate solution, indicating that the prepared thiosulfate solution
was weaker than 0.1 N, then it becomes necessary to establish by computation
a suitable correction coefficient which is derived by dividing 10 by the number
of ml actually used in the titration; e.g., if the titration consumed 10. 2 ml
then the correction coefficient will be 10 -=- 10.2. The 0.01 N thiosulfate solu-
tion is prepared by properly diluting the 1 N or 0.1 N thiosulfate solution with
double distilled water.
Apparatus and dishes.
1. Aspirator of 5 li capacity.
2. Volumetric flask 100 ml capacity.
3. Erlenmeyer flask 50 ml capacity.
4. Chemical beaker 100 ml capacity.
5. Burette with a glass stopcock and stand.
6. Graduated pipettes 10 nil capacity.
7. P.etri Polezhaev absorber of 30 ml capacity.
8. Analytical balance.
Analytical procedure. Place 20 ml of 2. 5% sodium iodide solution of
acetone into an absorber and aspirate through it 2-3 li of the investigated air
at the rate of 200 ml per min. Iodine will be liberated according to the
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following formula: . • .
»I 2 + CO+2NaCl.
Pour the absorber content into a 100 ml volumetric flask, wash the
absorber with pure acetone and add to the volumetric flask; 'fill the flask to
the 100 ml mark. Take 25 ml of the solution, add 10-15 ml of distilled water
and titrate with 0.01 N standard sodium thiosulfate solution using starch as
the. indicator, to the point of the blue color disappearance. The reaction
proceeds as follows:
Calculation of results. Use the following formula:
V-0.49-V,
C=-
V,-W
in which C represents the mg/li of phosgene in the air;
V represents ml of 0.01 N sodium thiosulfate solution used
in the titration;
Vj_ represents ml of the volumetric flask into which the solu-
tion was poured from the absorber;
V2 represents ml of solution taken from the absorber;
W represents li of air aspirated through the absorber.
If all specifications for this determination have been carefully observed then
the calculation of results can be carried out according to the following
formula:
The symbols have the same designation as described above.
ACETYLENE (C2H2)
Acetylene is a colorless gas having a weak odor; it is easily soluble in
water and more so in alcohol and acetone. The mol. wt of acetylene is 26.04.
One ml of acetylene at 0° and 750 mm of mercury weighs 1.171 mg. Its
density as compared with air is 0.9057 and its mol. vol. is 22.22; b.p.. is
83.6°. . .
Toxicology
The toxicity of acetylene is weak and its effects begin with 60-70% of the
substance in the air. Inhalation of acetylene produces narcosis. 'Grave toxic
manifestations appear to be due to the inhalation of accompanying toxic
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admixtures. No limit of allowable acetylene concentration in the air has
been officially established; 0.5 mg/li has been proposed in 193L without any
basic reason.
Qualitative Reaction
The Copper Oxide -Ammonia-Hydroxylamine Method
The principle of the method as presented by P. N. Losway is based on the
fact that a solution of copper oxide in ammonia containing hydroxylamine
ac_q_uires_a brillian red color in the presence of acetylene.
Reagents. 1. Copper nitrate, crystalline, c.p. 2. Ammonium hydrox-
ide, 30% solution. 3. Hydroxylamine hydrochloride , crystalline, c.p.
Prepare the final solution as follows: dissolve 1 g of copper nitrate in 15 ml
of distilled water and add 4 ml of 21% ammonia and 3 g of hydroxylamine
hydrochloride.
Analytical procedure. Shake the mixture prepared as above to disappear-
ance of all color, add distilled water to the 50 ml mark and mix; saturate
plugs of cotton with this solution; dry and insert into glass tubes. Evaluate
results by comparison with colors of the cotton of a previously prepared
standard scale, as indicated on page 3. Filter paper can be used in the place
of cotton.
The Ammonium Chloride and Copper Sulfate Method
Reagents. 1. Ammonium chloride, crystalline, c.p. 2. Copper sul-
fate, crystalline, c.p. 3. Hydrochloric acid, sp.gr. 1.19. 4. Copper
shavings.
Place 175 ml of distilled water into
a 250 ml volumetric flask and add 50 g of NrT4Cl and 25 g of CuSO^, then add
0.5 ml of concentrated HC1 of 1.19 sp.gr.; add distilled water to the 250 ml
mark. Take 5 ml of this solution in a-glass beaker and add 0.4 g of copper
shavings, heat to complete discoloration; add 1 ml of distilled water, then
cool rapidly and dip filter paper into it.
Analytical procedure. In the presence of acetylene the indicator filter
paper -will acquire a bright -red color. Evaluate results as described in
page 3. The presence of hydrogen sulfide interferes with the determination.
Therefore, where the presence of such a gas in the air is suspected elimi-
nate it by first passing the air through an absorber containing lead acetate.
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BENZENE VAPOR (C6H6)
Benzene is a colorless liquid having an aromatic odor; it is easily solu-
ble in ether and absolute ethyl alcohol; its mol. wt. is 78.11. One ml of
C6H5 weighs 3.25 mg; its density at 20° and 760 mm of mercury is 0.879; its
b. p. is 80.1 and f. p. 5.4-5. 5°. . . .
Toxicology
Benzene is highly toxic. It acts as a narcotic and elicits spastic con-
vulsions-.-- B-enzene poisoning ran be. r&cuo-gni^&d by the following symptoms:.. . __
a state simulating drunkenness, muscular weakness, uncertainty of gait,
convulsive twitching, rapid respiration followed by slow respiration and
disturbed function of hemopietic organs. Inhalation of air containing
20-30 mg/li of benzene causes rapid death; the official allowable benzene
concentration in atmospheric air is 0.02 mg/li.
» Qualitative Reaction
The Formalin. Method
This method was proposed by Kobayasi and is based on the fact that as-
piration of the investigated air through an indicator tube containing the proper
indicator gel acquired a rose-red to brown color. The author suggested no
chemical reaction.
Reagents. 1. Sulfuric acid, 1.84 sp.gr. 2. Formalin, 40% solution.
3. Silicagel, purified.
Preparation of the indicator reagent. Place 20 ml of HgSO4 into a glass
beaker submerged into ice water. Add gradually with constant stirring
2. 5 ml of the 40% formalin solution. Moisten granular silicagel of
0. 25-0. 35 mm in diameter \vith the formalin sulfuric acid solution, adding
5 nil of the reagent for each 10 g of the silicagel; place the silicagel into
glass tubes 60 mm long, 2-2.5 mm of inside diameter to form a 5 mm column.
Secure the silicagel in the tubes by forcing in glass wool plugs at each end of
tlie indicator tube.
Analytical procedure. Aspirate 5 li of the investigated air through the
indicator tubes; 3 minutes later observe the color of the indicator gel as
described in page 15. Other aromatic compounds interfere with a reaction.
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Quantitative Determination
The Potassium Periodate Method
E.D. Filyanskaya and others proposed a linear colorimetric method for
the determination of benzene vapor in the air. The silicagel indicator used in
this method is prepared by saturating the granular material with a solution of
KIO3 in sulfuric acid followed by drying. This liberates I305 anhyride which
reacts with the benzene vapor forming a substance of a dark grey color.
Reagents. 1. Sulfuric acid of 1.84 sp.gr. 2. Potassium periodate,
(KI03) c. p. 3. Silicagel, purified-.
Preparation of the indicator powder. Place 75 ml of sulfuric acid into a
250 ml flask with a. ground-to-fit stopper; add 1.25 g of KIO3 and mix to com-
plete dissolution. Take 0.4 ml of this solution, place into a glass beaker and
add 1 g of the purified granular silicagel of 0.16-0.25 mm in diameter; mix to
complete moistening of the powder and dry at 175-185° with frequent mixing
with a glass rod. Place the prepared indicator powder into wide;mouth
bottles with ground-to-fit stoppers; after the powder had completely cooled
transfer it into indicator glass tubes and seal hermetically by fusing. The
silicagel layer in the .indicator tube should be 4-5 mm long.
Apparatus and dishes.
1. 250 ml glass flasks.
2. Drying hood.
3. Pipettes, graduated in 1 ml.
4. Volumetric 100 ml cylinder.
5. 20 ml wide-mouth bottles with ground-to-fit stoppers.
6. Chemical tubes.
7. Glass tubes, 60 mm long, 4 mm inside diameter.
Analytical procedure. Aspirate the investigated air through the opened
indicator tubes at a standard rate and a standard volume in all tests made.
Calculation of results. Evaluate results by the procedure described on
page 3.
ETHYLENE OXIDE (C2H4O)
Ethylene oxide is a liquid having a b.p. of 10. 7°; a sp. gr. at O° of 0.894;
it mixes with water in all proportions. Ethylene oxide reacts with water at
high temperature forming ethylene glycol and polyethylene alcohols as inter-
mediate products. C2H2OH2 is easily soluble in alcohol and ether; its mol. wt.
is 44.05.
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Toxicology
EthyLene oxide acts as a narcotic; it is a potent cellular poison. Inhala-
tion of air containing 0.05 up to 0. 01 mg/li of ethylene oxide for several hours
induces a state of poisoning accompanied by nausea, vertigo and disturbed
cardiac activity. The limit of allowable ethylene oxide vapor concentration in
the air was officially set at 0.001 mg/li.
Qualitative Reaction
The Aluminum Chloride and Fuchsin Sulfuric Acid Method
This method, proposed by Deckert, is based on the fact that in the pres-
ence of aluminum chloride ethylene oxide becomes isonrierized into acetic
aldehyde. The reaction proceeds as follows:
II H
I I
H—C—C—H^,
\/ I H '
O H
The latter substance can be colorimetrically deternained with the aid of
fuchsin sulfuric acid. '
Reagents. 1. Aluminum chloride, crystalline. 2. Fuchsin-sulfuric
acid, 0. 02% solution.
Insert glass wool into a glass tube to form a layer of 2 cm long; moisten
the glass wool with a mixture of solutions 1 and 2 in 1:10 ratio; prepare solu-
tion 1 by dissolving 50 g of crystalline aluminum chloride in 100 ml.of dis-
tilled water; prepare solution 2 by dissolving 0.02 g of fuchsin-sulfuric acid
in 100 ml of distilled water. . -
Analytical procedure. Aspirate 4: li of the studied air through a tube con-
taining glass wool moistened with the indicator. If the air contains ethylene
oxide in concentration exceeding 0.025% by volume, then the glass wool indi-
cator will acquire a red .color; at lower C2H4O concentrations the indicator
may remain colorless or acquire a light rose tint.
ANILINE (CSH5NH2)
Aniline is a colorless oily liquid which has an aromatic odor; its mol.-wt.
is 93.12 and sp.gr. at 20° is 1.022. Resinification imparts to aniline a yellow-
color; it easily volatilizes at room temperature. Aniline is sparsely soluble
in water; it is easily soluble in ethyl alcohol, in ether, and in acetone; 1 li of
air at 15° may- contain 0. 9 mg; at 25°, 1.8 mg, and at 40U 5 mg of aniline. .
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Toxicology
Aniline is a central nervous system stimulant and affects the cardio-
vascular system; upon entering the blood system aniline forms methemo-
globin which markedly lowers the capacity of hemoglobin to bind oxygen.
Clinical symptomotology of aniline poisoning is usually as follows: headache,
vertigo, lowered appetite, enlargement and tenderness of the liver and rapid
pulse. Chronic poisoning -with aniline usually produces high blood pressure
and bradycardia; shifts in. the blood morphology, such as reduced number of
erythrocytes, lowered hemoglobin concentration and affected kidneys. Chronic
exposure to aniline vapor has been known to result in blastomogenesis. The
limit of allowable aniline concentration in the air has been officially set at
0. 003 mg/li.
Quantitative. De te r mination
The P-dimethylaminobenzaldehyde Acetic Acid Method
This method is based on the principle of aniline condensation with
P-dimethylaminobenzaldehyde in the presence of acetic acid. The reaction
results in the development of a yellow color, the intensity of which varies
with the concentration of the aniline.
Reagents. 1. P-dimethylaminobenzaldehyde, 5% solution. 2. Acetic
acid, 50% solution. 3. Glass wool.
Preparation of the indicator paper. Prepare strips of high quality ash-
free filter paper and saturate with 5% solution of P-dimethylaminobenzalde-
hyde in 50% acetic acid; dry between sheets of filter paper to a point where
the moisture content will equal 5-10% of the weight of the paper; store the
indicator paper in tightly closed glass bottles .for not longer than 48 hours.
Apparatus.
1. Porcelain dish or Petri dish.
2. Cylinder graduate, 50 ml.
3. High grade ash-free filter paper.
4. Brown glass reagent bottle.
5. Aspirator.
6. Glass tube with 2-3 mm inside diameter.
Analytical procedure. Aspirate 50-400 ml of the air through two indicator
saturated filter papers at the rate of 100 ml/min. In the presence of aniline
vapor in the air the spot of the paper through which the air was aspirated will
turn yellow, which will persist for 20 minutes. The intensity of the yellow
color is then compared with an artificial scale of colors on Whatman filter
paper. Intensities of the color scale should represent 0. 03, 0.06, 0.1, 0.15,
0.37, 0.75, 1.0, 1. 5 and 2.3 y.
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Calculation of results. See page 15.
By this method 0. 01 down to 0.00002 mg/li of aniline in the air can be
determined in 10-15 minutes.
ACETONE (CH3~ CO-CH3)
Acetone is a colorless mobile fluid which has a specific odor; its mol.wt.
is 58.08, sp.gr. at 20° is 0.792. Acetone is easily soluble in water, alcohol
and ether.
Toxicology
High concentrations of acetone irritate the mucosa of the respiratory
passages and of the eyelids. Under chronic conditions acetone produces a
catarrhal condition of the upper respiratory passages and of the conjunctiva.
It also affects the morphologic blood picture. The limit of allowable acetone
concentration in the air was officially set at 0.2 mg/li.
Qualitative Reaction
The Sodium Nitroprusside and Mercuric Chloride Method
This method was proposed by Sinochara and is based on the fact that
the indicator saturated filter paper turns violet blue in the presence of acetone.
Reagents. 1. Sodium nitroprusside, c.p. 2. Mercuric chloride,
crystalline, c.p. 3. Ammonium sulfate, c.p. 4. Sodium carbonate, c.p.
Preparation of the reagent. Dissolve 5 g of the .sodium nitroprusside in
1,000 ml of distilled water; add 1. 8 g of HgCl2; wait until it dissolves, then
add 50 g of (NH4)3SO4, after this is dissolved. Saturate the filter paper with
this solution and perform the analysis as described on page 3.
•* *
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APPENDIXES
APPENDIX I
APPENBIX 2
PERCENT OF SULFURIC ACID IN SOLUTIONS
OF DIFFERED SPECIFIC GRAVITY
SP.SR.
AT 15°
1.010
1,020
1,030
1,040
1,050
1,060
1,0 7U
1,080
1.090
1,100
1,110
1,120
1.130
1,140
1.150
1,160
1,170
• 1.180
1.I9U
1,200
1,210
1,220
1,230
1,240
1,250
1.260
1,270
,1,280
1,200
1.300 '
1,310
PERCENT
OY WEIGHT
1,57
3,03
4.49
5.%
7.37
8.77
10,19
11.60
12,99'
. 14.35
15.71
17,01
18.31
19.61
20,91
22.19
23.47
24.76
26.04 '
27.32
28,58
29.84
31,11
32,28
33.43
34,57 '
35.71
36,87
38,03
39,19
4035
SP.GR.
AT 15°
1,320
1,330
.340
.350
.360
,370
.380
. ,390
,400
,410
.420
,4oO
.440 '
,450
,460
.470.
.480
,490
,*00
,510
1,520
1,5 JO
1,540
1.550
. 1.560
1.570
1,580
1,590
i.eoo
1.610
1,620
1 PERCENT
|tY WEIGHT
41,50
42,66
43,74
44,82
45,88
46.94
48.00
49,06
50,11
51,15
52,15
53,11
54,07
55.C3
55,97
56,90
57,83
58.74
59.70
60,65
61,59
62.53
63.43
• 64.26
65.08
65.90
66,71
67.59
68.51
69,43
70,31
| SPoGR.'
| • AT 15"
l.SSO
1,640
1,650
1,660
1.670
1.680
1,690
• 1,700
• 1,710
1.720
1.730
1.740
1.750
1.760
1.770 -
1.78U
1,790
1,800
1,810
1,620
1,822
1,824
1,826
1,828
1/30
1,832
1,834
1,836
•1.838
1,840
~
PERCENT
BY' WEIGHT
71,16
71,69
72,82
7J.64
74,51
75.42
76,30
77,17
78,04
78.92
79,80
80,68
81.56
. 82,44
83,32
84,50
85,70
86,90
88.30
90,05
90,40
90,80
• 91,25
91.70
92,10
92,52
93.05
93.80
94,60
93*0
~
PERCENT OF HYDROCHLORIC AND NITRIC ACIDS
IN SOLUTIONS OF DIFFERENT SPECIFIC GRAVITY
SP.GR.
AT 15°
1.01
1.02
1,03
1,04
1.05
1.06
1.07
1.08
1,09
1,10
1.11
1,12
1.18
1.14
1.15 *
1,16
1.17
1,18
1.19
1.20
1,21
1.22
• 1.23
1,24
1,25
1,26
PERCENT BY WEIGHT'
HCl
2,14
4.13
6.15
8.16
10,17
12,19 -
14,17
. 16,15
18,11
20,01
21.92
23,82
25,75
27.66
29,57
31,52
33,46
35,39
37,23
39.11
HNO,
1,9!)
3,70
5.50
7,26
8,93
10.68
. 12,33
13,95
15,53 •
17,11
18,67
20,23
21,77
23,31
24,84
26,36
27.88
29,38
30,88
32.36
33.82
35,28
36,78
38.29
39,82
41,34
P
SP.GR.
. AT 15°
1,27
• 1.28
1,29
1,30
1,31
1,32
' 1,33
1.34
1.35
1,36
1,37
I, .38
1,39
1,40
1.41
1,42
1,43
1,44
1,45
1,46
1.47
1,48
1,49
1,50
1.51
1,52
PERCENT
OY WEIGHT
42,87
44,41
45.95
47,49
49,07
50.71
52.37
54,07
' 55,79
57.57
59,39
61,27
63,23
65,30
67,50
69.80
72,17
- 74,68
77,28
79,98 •
82,90
86.05
89.90
94.09
98.10
99.67
-------
APPENDIX 3
APPENDIX 4
PERCENT OF KOH AND NAOH IN SOLUTIONS
OF DIFFERENT SPECIFIC GRAVITY
SYMBOLS AND ATOMIC WEIGWS OF MOST
IMPORTANT CHEMICAL ELEMENTS
'SP. GR. AT 15°
1.014
1,029
1.045
1.060
' 1.075
i,091
1.108
1.125
1.142
1.162
1,180
1,200
1.220
1,241
1,252
1,27V •
1,297
1,320
1.345
1,370
1.397
1,424
1.453
1.483 • •
1.514
1.546
1.580
1,615
PBRCEKT BY WEIGHT
N«OH
1.20
2,71
4.00 .
.. 5.29
6,55'
8.iX)
9.12
H',97
• 12,64
14,37
15,91
17.67
19,58
21,42
22,64
2-4,81
26,83
• 28.83
31,22
33.69
36,25
38,80
. 41,41
44.38
47.60
—
—
—
KOH
1.7
3.5
5.6
7,4
9.2
Hi. 2
12,9
14.8
16,5
18,6
20.5
22.4
24,2
26,1
27,0
28,9 .
•30,7
32,7
34.9
36,9
38.9
40.9
• 43,4
45,8
48.3
50,6
53,2
55,9
NAME
SYI^-
BOL
A 1
Ar
Ra
B
Rr
v
H
Ho
Po '
A ti
J
CA
Ca
f~r\
Si
Mrr
rag
Mn
Cu
Mo
Ac
ATOMIC
WEIGHT
1 A fYlfl
9fi Qfi
?Q Q44
137 30
1082
7Q Qlfi
5095
1 008
20<30
1 QO GO
A (VVJ
ee oc
1O7 9
126,91
11241
39 10
4008
160
•yi
-------
APPEXII* 5
CKEKICAL ECUIVALEI.7S
S-JrSTATCE
rOR.TJLA
1
» UJ
_J —I
f> •<
C >
5 —
UJ
I-
« z
o —
3
H
^ K-
j S
— 3
c/
UJ
REMARKS
111 NEUTRALIZATION REACTIONS
BARIUM HYoaoxn-.-...
CALCIUM KYSROXIBE-...
HYDROCHLORIC AC IB....
OXALIC ACID
POTASSIUM HYDRGXISE--
SODIUM CAFSCfUTE
SODIUM CAF30IIATE.....
SODPJK mAHBO'.'ATE...
tta (Utt)3
Ba(OHo-SHjO)
Ca(OH),
HCI
HNOj
hUSO,
H-C3O4-2HjO
NaOH
KOH
Na,CO,
Na,CO,
N«HCO3
2
2
1
1
2
2
]
L
1
2
2
1
I/I.JH
315.50
74.10
36,47
63,02
98.08
126,06
400
5B.IO
106,00
106,0
84,02
S.'i.b!)
157.75
35,05
36,47
63.02
49.04
63.03
4000
loe'.oo
53.0
84,02
ANHYDROUS
HYDROUS
PHEHOLPHTHALEIN
TITRATIOH
METHYL ORAHSE
TITRATION
OxrOATICM-SESUCTIOK REACT! 0!IS
SCDIl',1 OXALATE.,...o.
SODIUM Sl'LFITE ,
FOTA.SSI i'«
FOTASSI DM
POTASSIUM
Dl CKS OMjl" E, . , . ,.oo.
CXALIO ACI3 o.o.
(-YD20SES f?ROXI5H....
POTASSIUM CHRC:HTEC«.
Na,C,04
Na,S303
KMnO
1 »i*lll '—'4
KMnO,
KjCr-O7
H2C,b,
H^Oj
K,CrO,
2
1
c
o
3
6
2
3
134,00
248.2
1 ^ 04
158.04
294,21
9o!i,4
34.02
194,19
67,00
248,2
**I fil
5?,£8
49 035
45.02
I7.ol
64.73
1 II ACID MEDIUM
l» ALKALINE
MEDIUM
! '.' PRECIPITATIOfl REACTIONS
SlLV£-. !!I7?.ATE
SODIUM OH LOR ID £...«„.
FOTAS5I UH CHLOT 10 E...
SARIUM CHLOBIOC. ...<»
AgNO,
NaCl
KC1
Bad,
1
1
I
2
169,9
58.45
.74.55
208,27
169,9
58.45
74,55
104,13
-101-
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Appendix 6
Formulas and Calculations
1. Conversion of gas concentrations in the air from volume percent
to weight concentration in mg/li at O° and 760 mm mercury column.
C-m-p-0,45, (1)
where C represents gas concentration in mg/li;
m represents the gas mol. wt. ;
p volume in ml." " " - " -•-.-..--._
Example: Carbon monoxide concentration in the air is 0.23 vol. %.
What is its concentration in mg/li? Mol. wt. of CO (m) = 28.
Substituting absolute values in formula (l) obtain:
•', C-28.-0.23- 0,45-2,87
2. Conversion of gas concentrations originally expressed in mg/li to
volume concentration, i.e. ml percent concentration. Use formula below:
; " m-0.45 ' . (2)
where p, C, and m have the same designations as in (l).
3. Reduce gases to normal (standard) temperature and pressure:
(Ou and 760 mm mercury column).
. __ W273./7J
'; " 760-(273-M) \^l } •
where Vo represents the gas volume brought to normal temperature
(O°) and pressure (760 mm mercury column);
Vt represents the gas volume at prevailing air temperature and
barometric pressure;
t represents the gas temperature, i.e. the air temperature.
Example: 250 ml of oxygen was taken at 18° air temperature and 730 mm
barometric pressure. What will the volume be at standard
(normal) temperature and barometric pressure? Use formula '
(3). Substitute absolute values for corresponding symbols as
shcv/n below:
,', • 550.273-730 ooc or .
= ^o,/o mi
760-(273+18)
-102-
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Appendix 6 (cont'd)
V0 can also be determined by multiplying
Vj; by F, or a previously computed factor
as presented-.in the table below.
F =
273 -p
760-(27J-j-0
X. ATM.
X.PRESSURE
^v IK Vt\
TEMPERATURE^
10°
12°
14°
16°
18°
20°
22°
24"
26"
28°
30°
32°
34°
700
9.SS9
(X882
0.876
0.870
0.884
0.858
0,852
0,847
0,841
0.835
0.830
0.824
0,319
710
0.901
oisfls
n,8*9
0,883
0.876
0.870
0,865
0.859
0.853
0,847
0,842
0.836
0,831
720
0.914
O.S03
0,901
0,895
0,889
0,883
0,877
0,871
0,855
0,859
0,854
0.848
0,842
730
0.927
o;«2o
0.914
0,907
0.201
0.895
0.8S9
0.883
0,877
(',871
0.855
0.850
0.854
740
0.939
0.933
0,828
0,920
0.914
0.907
O.S01
0,895
0.889
0,88.3
0.877
0.872
0.86S
750
0.952
0.945
0,930
0,932
0.926
0.920
0.913
0.207
O.S01
0.895
0.689
0.833
0,878
760
0.955
0.958
0.951
0,945
0,938
0.932
0.925
0.919
0.913
0.907
0.901
0.695
0.889
770
0,977
0.971
O.S64
0,957
0,951
0,944
0.938
0.931
0.925
0.919
0.913
0.207
0.801
4. Preparation of mixtures of carbon monoxide and air, containing
given CO concentrations.
In many instances such mixtures may be required for the purpose of
checking the methods for the determination of CO in the air.
Prepare a rarefaction of CO in a gasometer. Calculate using the
following formula: :
V=
C-V,
1,25
where V is the desired volume of pure CO in ml run into the
gasometer;
C is the desired CO concentration in ml;
Vl is the total volume of the prepared mixture;
1. 25 is the weight of 1 li of CO in g.
Example: Prepare 10 li of a mixture containing 1 mg/li of CO.
-103-
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Appendix 6 (cont'd)
V=
MO
1.25
8 ml CO.
Run into a gasometer 8 ml of CO; add clean air up to 10 li'.. With this
as a stock mixture of CO-clean air prepare mixtures of concentrations
and in volumes as indicated in the table below.
TABLE OF CO CONCENTRATIONS IN AIR MIXTURES
YOU CF MIX-
TUH t HI Ml
500
500
500
800
SOO
625
500
500
800
800
635
CO CONCENTRA-
TION IN KG/I 1
1,0
0,5
0,25
0,125
0,100
0,08
0,05
0.025
0,0125
0,010
0,0008
VOL. OF ADBE8
AIR IN Ml
500
500
500
200
200
365
500
500
200
200
365
FINAL CO CONCH
1 N MG/I 1
0,5
0,25
0,125
0.100
0,080
0,050
0,025
0,0125
0,010
0.008
0.005
5. Calculation formulas for the preparation of any desired gas con-
centration from stock dilutions:
. a) Preparation of lower gas-in-air concentrations from higher
gas concentrations:
where V represents ml of higher gas concentration required to dilute
to lower concentration;
VL represents total volume of the required gas dilution in ml;
p % concentration of the required gas dilution;
P % concentration of the original or stock gas dilution.
Example: Prepare 150 ml of 3.5% concentration of any substance from
a 25% stock solution.
150-3,5
~
_
2\ ml
Take 21 ml of the 25% solution and add clean air to 150 ml.
b) What will be the % concentration (p) of a substance in solution
if to volume V having a P concentration Vx of clean air was added.
-104-
-------
Appendix 6 (cont'd)
v.p
Example: Fifteen ml of a 22% solution was diluted to 100 ml by the
addition of 85 ml of clean water. Find the final dilution
in percent.
c) The strength of a solution is frequently expressed in terms of
dilution ratios, such as 1:25, 1:5, etc. The final dilution
obtained after the addition of a given volume of the diluent in
such cases can be determined by the following formulas.
Example: What is the final dilution (l:b) when a diluent volume Vl
was added to volume (V) of a l:a dilution? Use the
following formula:
where b is the dilution multiple desired;
a is the original dilution multiple;
Y! is the volume of added diluent in ml
V is the volume of the original solution.
Example: What dilution degree will result from the addition to 50 ml
of 1:30 solution of 25 ml of pure diluent?
30 (25-1-50) =
d) Determine volume (V) of a given dilution (l:a) required to obtain
dilution degree (l:b) by the addition of diluent (water or air)
volume (V1). Use the following formula:
,/«•"•
b-a •
in which symbols have the same designation as above.
Example: How many ml of a 1:60 dilution must be added to 100 ml of
water to obtain a 1:300 dilution?
-105-
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Appendix 6 (cont'd)
V—-
300-50
(e) To obtain sulfuric acid solutions of different percent concen
trations by weight, use the following formula:
where V is the volume of strong sulfuric acid which must be added
to 100 ml of water;
p is the required percent concentration of sulfuric acid;
P is the percent concentration of the strong sulfuric acid;
d is the specific gravity of the strong sulfuric acid.
Where the percent concentration of the sulfuric acid is 95.6 and
its specific gravity is 1. 84, the above formula can be reduced to:
V°p. 0,558 ml
-106-
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JIHTEPATYPA
A;i«KcceBa M. B. 3aooacj. OS-beKTHBHbiii (p.nyopecueHTHbu'i MBTOA aHa^iisa B
inpaK-nixe rnraempiecKoro ncc^eAOBannd BOSAyxa. HOBOCTH we-
AKUiiiibi, .1952, IB. 26.
OQAOTOB B. n. SKcnpecciibm MBTOA onpeac.iCHnn (popMajibAeniAa
D iBOSAyxe. PiHriieiia n caiiHiapiiH, 1956, J^T? 9. 85.
QUAD HC-Kan E R. n AP- JIi[HeHHO-,Ko.aopncTH'iecKiiii MeroA ana-'
jiHsa -BpeAHbix rasoa n napos B B03jyxe npo.Mbiuj.neiiHbix npeA-
npHHTHH. HpocpMAaT, 1958.
Qua a HCIX a,a E ZI. FIpiiOop onpeAeJieiuia cepoaoAOpOAa H aMMiia-
Ka D BOSAyxe, B1IHHOJ1 BUCOC. JI., 1951.
OoMnqeD'3 H. H. OnpeaMeime cepimcToro aiiniApiiAa B Boajiyxc
iipn noMOiuii .iniAHKaTOpiibix TpyfioK. PiirneHa n SAOposbe, 1941.
j»f9 9 9—10.
lUnpcK'aH B A. Bucrpbiii MCTOA onpeAe.nemm osona opTOTOrtHAH-
HOM B «H.: Onpeae-nemie apCA-Hbix BeiueciiB B Bosayxe, PDA
O. R. Xa.iiiaoBoii. MeAniis, M., 1957.
-107-
-------
Arm it K. A. J. of Hyg.; 1908, 8. 565.
Beckmann. Anaiyt. Chcm.. 1948, 20, N. 7., 674—677.
Berisso K. M. Publ. list, invest, microg., 1950. 14, 199.
Cherrard G. C. U. S. Pub. Health, Cervice, Reprint.," 1928, 12—
22.
Deckert W. Z. Z. Anal. Chcm., 1956. 150, N. 6, 421—425; Abgew.
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Dlxon B. C. Analyst, 1958, 83, 199—202.
Forles J. J. U. S. Bur. Miners Circ.. 1938, 33.
Fuches W. S. Techniknacluichten. .1957, 7, N. 6, 273.
Jacobs M. B. Chemfcat analysis of- rrtdustria-J—- sevens. New
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Ko 1th off J. M., Dansel E. B. Textbook of Quantitative Inor-
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Kobayaschi V. J.Chem. Soc. Japan, Industr. Chem. Soc., 1955,
58. N. 9. 651—654.
Kobayaschi V. J. Chem. Soc. Japan. Industr. Chem. Soc., 195-1.
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Lap in L. N. Z. anal. Chem., 1935, 102, 418. I
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Woog P. J. de Saint-Mars. Bull. Soc. Chem., 1935, 5, N. 2, 1214
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Zeaflet Z. K. Dept. Sci. Ind. Research. Brit.. 1939, 7.
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