vvEPA
United States
Environmental Protection
Agency
Environmental Monitoring Systems
Laboratory
Research Triangle Park NC 2771 1
EPA-600/4-84-041
Apr 1984
Research and Development
Compendium of
Methods for the
Determination of
Toxic Organic
Compounds in
Ambient Air
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EPA-600A-8l»-04l
April 1984
COMPENDIUM OF METHODS FOR THE DETERMINATION
OF TOXIC ORGANIC COMPOUNDS IN AMBIENT AIR
by
R. M. Riggin
Battelle-Columbus Laboratories
505 King Avenue
Columbus, Ohio 43201
Contract No. 68-02-3745 (WA-9)
EPA Project Officer:
L. J. Purdue
Quality Assurance Division
Environmental Monitoring Systems Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, North Carolina 27711
ENVIRONMENTAL MONITORING SYSTEM LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
RESEARCH TRIANGLE PARK, NORTH CAROLINA 27711
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Disclaimer
This report has been reviewed by the Environmental Monitoring
Systems Laboratory, U. S. Environmental Protection Agency, and
approved for publication. Mention of trade names or commercial
products does not constitute endorsement or recommendation for
use.
ii
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CONTENTS
Page
FOREWARD iv
INTRODUCTION v
METHODS
Tenax GC Adsorption Method TO-1
Carbon Molecular Sieve Adsorption Method TO-2
Cryogenic Trapping Method TO-3
High Volume Polyurethane Foam Sampling Method TO-4
Dinitrophenylhydrazine Liquid Impinger Method TO-5
Sampling
APPENDIX A - EPA Method
111
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FOREWARD
Measurement and monitoring research efforts are designed to
anticipate potential environmental problems, to support regulatory
actions by developing an in-depth understanding of the nature and
processes that impact health and the ecology, to provide innovative
means of monitoring compliance with regulations, and to evaluate the
effectiveness of health and environmental protection efforts through
the monitoring of long-term trends. The Environmental Monitoring
Systems Laboratory Research Triangle Park, North Carolina, has
responsibility for: assessment of environmental monitoring
technology and systems; implementation of Agency-wide quality
assurance programs for air pollution measurement systems; and
supplying technical support to other groups in the Agency, including
the Office of Air and Radiation, the Office of Toxic Substances, and
the Office of Enforcement.
Determination of toxic organic compounds in ambient air is a
complex task, primarily because of the wide variety of compounds of
interest and the lack of standardized sampling and analysis procedures.
This methods compendium has been prepared to provide a standardized
format for such analytical procedures. A core set of five methods is
presented in the current document. Addition of specific methods to
the compendium will occur as suitable methods become available.
Additionally, the current methods may be modified from time to time
as advancements are made.
Thomas R. Mauser, Ph.D.
Director
Environmental Monitoring Systems Laboratory
Research Triangle Park, North Carolina
iv
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INTRODUCTION
This Methods Compendium has been prepared to provide regional,
state, and local environmental regulatory agencies, as well as other
interested parties, with specific guidance on the determination of
selected toxic organic compounds in ambient air. Recently, a
Technical Assistance Document (TAD) was published which provided
guidance to such persons (1). Based on the comments received
concerning the TAD the decision was made to begin preparation of a
Methods Compendium which would provide specific sampling and analysis
procedures, in a standardized format, for selected toxic organic
compounds.
The current Methods Compendium consists of five procedures which
are considered to be of primary importance in current toxic organic
monitoring efforts. Additional methods will be placed in the
compendium from time to time, as such methods become available.
The current methods were selected to cover as many compounds as
possible (i.e. multiple analyte methods were selected). Future
methods are expected to be targeted towards specific compounds, or
small groups of compounds which, for various technical reasons,
cannot be determined by the more general methods.
Each of the methods writeups is self contained (including pertinent
literature citations) and can be used independent of the remaining
portions of the Methods Compendium. To the extent possible the
American Society for Testing and Materials (ASTM) standardized format
has been used, since most potential users are familiar with that
format. Each method has been identified with a revision number and
date, since modifications to the methods may be required in the future.
Nearly all the methods writeups have some flexibility in the procedure.
Consequently, it is the user's responsibility to prepare certain
standard operating procedures (SOPs) to be employed in that particular
laboratory. Each method indicates those operations for which SOPs are
required.
Table 1 summarizes the methods currently in the compendium. As shown
in Table 1 the first three methods are directed toward volatile nonpolar
compounds. The user should review the procedures as well as the back-
ground material provided in the TAD (1) before deciding which of these
methods best meets the requirements of the specific task.
Table 2 presents a partial listing of toxic organic compounds which
can be determined using the current set of methods in the compendium.
Additional compounds may be determined by these methods, but the user
must carefully evaluate the applicability of the method before use.
Reference
1. Riggin, R. M., "Technical Assistance Document for Sampling and
Analysis of Toxic Organic Compounds in Ambient Air", EPA-600/4-
83-027, U. S. Environmental Protection Agency, Research Triangle
Park, North Carolina, 1983.
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TABLE 1. LIST OF METHODS IN THE COMPENDIUM
Method
Number
Description
Types of
Compounds Determined
TO-1
TO-2
TO-3
Tenax GC Adsorption and
GC/MS Analysis
Carbon Molecular Sieve
Adsorption and GC/MS
Analysis
Cryogenic Trapping
and GC/FID or ECD
Analysis.
Volatile, nonpolar organics
(e.g. aromatic hydrocarbons,
chlorinated hydrocarbons)
having boiling points in the
range of 80 to 200°C.
Highly volatile, nonpolar
organics (e.g. vinyl chloride,
vinylidene chloride, benzene,
toluene) having boiling points
in the range of -15 to + 120°C.
Volatile.nonpolar organics having
boiling points in the range of
-10 to + 200°C.
TO-4
TO-5
High volume PUF
Sampling and GC/ECD
Analysis.
Dinitrophenylhydrazine
Liquid Impinger Sampling
and HPLC/UV Analysis.
Organochlorine pesticides and
PCBs
Aldehydes and Ketones
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TABLE 2. LIST OF COMPOUNDS OF PRIMARY INTEREST
Compound
Applicable
Method(s)
Comments
Acetaldehyde
Acrolein
Acrylonitrile
Ally! Chloride
Benzaldehyde
Benzene
Benzyl Chloride
Carbon Tetrachloride
Chlorobenzene
Chloroform
Chloroprene
(2-Chloro-l,3-butadiene)
4,4'-DDE
4,4'-DDT
1,4-Dichlorobenzene
Ethylene dichloride
(1,2-Dichloroethane)
Formaldehyde
Methyl Chloroform
(1,1,1-Trichloroethane)
Methylene chloride
Nitrobenzene
Perchloroethylene
(Tetrachloroethylene)
Polychlorinated biphenyls
(PCBs)
Propanal
Toluene
TO-5
TO-5
TO-2, TO-3
TO-2, TO-3
TO-5
TO-1, TO-2, TO-3
TO-1, TO-3
(TO-1?) TO-2, TO-3
TO-1, TO-3
(TO-1?) TO-2, TO-3
TO-1, TO-3
TO-4
TO-4
TO-1, TO-3
(TO-1?) TO-2, TO-3
TO-5
(TO-1?) TO-2, TO-3
TO-2, TO-3
TO-1, TO-3
TO-1, (TO-2?), TO-3
TO-4
TO-5
TO-1, TO-2, TO-3
TO-3 yields better recovery
data than TO-2.
TO-3 yields better recovery
data than TO-2.
TO-3 yields best recovery data.
Breakthrough volume is very low
using TO-1.
Breakthrough volume is very low
using TO-1.
The applicability of these methods
for chloroprene has not been
documented.
Breakthrough volume very low using
TO-1.
Breakthrough volume very low using
TO-1.
TO-2 performance has not been
documented for this compound.
vii
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TABLE 2. (Continued)
r . Applicable
Compound Methnd(«;) Comments
Trichloroethylene TO-1, TO-2, TO-3
Vinyl Chloride TO-2, TO-3
Vinylidine Chloride TO-2, TO-3
(1,1-dichloroethene)
o,m,p-Xylene TO-1, TO-3
viii
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METHOD TOT Revision 1.0
April, 1984
METHOD FOR THE DETERMINATION OF VOLATILE ORGANIC COMPOUNDS
IN AMBIENT AIR USING TENAX® ADSORPTION AND
GAS CHROMATOGRAPHY/MASS SPECTROMETRY (GC/MS)
1. Scope
1.1 The document describes a generalized protocol for collection
and determination of certain volatile organic compounds
which can be captured on Tenax® GC (poly(2,6-Diphenyl
phenylene oxide)) and determined by thermal desorption
GC/MS techniques. Specific approaches using these techniques
are described in the literature (1-3).
1.2 This protocol is designed to allow some flexibility in order
to accommodate procedures currently in use. However, such
flexibility also results in placement of considerable
responsibility with the user to document that such procedures
give acceptable results (i.e. documentation of method performance
within each laboratory situation is required). Types of
documentation required are described elsewhere in this method.
1.3 Compounds which can be determined by this method are nonpolar
organics having boiling points in the range of approximately
80° - 200°C. However, not all compounds falling into this
category can be determined. Table 1 gives a listing of
compounds for which the method has been used. Other compounds
may yield satisfactory results but validation by the individual
user is required.
2. Applicable Documents
2.1 ASTM Standards:
01356 Definitions of Terms Related to Atmospheric Sampling
and Analysis.
E355 Recommended Practice for Gas Chromatography Terms and
Relationships.
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T01-2
2.3 Other documents:
Existing procedures (1-3).
U.S. EPA Technical Assistance Document (4).
3. Summary of Protocol
3.1 Ambient air is drawn through a cartridge containing ^1-2
grams of Tenax and certain volatile organic compounds are
trapped on the resin while highly volatile organic compounds
and most inorganic atmospheric constituents pass through the
cartridge. The cartridge is then transferred to the
laboratory and analyzed.
3.2 For analysis the cartridge is placed in a heated chamber and
purged with an inert gas. The inert gas transfers the
volatile organic compounds from the cartridge onto a cold trap
and subsequently onto the front of the GC column which is held
at low temperature (e.g. - 70°C). The GC column temperature is
then increased (temperature programmed) and the components
eluting from the column are identified and quantified by mass
spectrometry. Component identification is normally accomplished,
using a library search routine, on the basis of the GC retention
time and mass spectral characteristics. Less sophistacated
detectors (e.g. electron capture or flame ionization) may be
used for certain applications but their suitability for a given
application must be verified by the user.
3.3 Due to the complexity of ambient air samples only high resolution
(i.e. capillary) GC techniques are considered to be acceptable
in this protocol.
4. Significance
4.1 Volatile organic compounds are emitted into the atmosphere from
a variety of sources including industrial and commercial
facilities, hazardous waste storage facilities, etc. Many of
these compounds are toxic; hence knowledge of the levels of
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TO!-3
such materials in the ambient atmosphere is required in order
to determine human health impacts.
4.2 Conventional air monitoring methods (e.g. for workspace
monitoring) have relied on carbon adsorption approaches with
subsequent solvent desorption. Such techniques allow
subsequent injection of only a small portion, typically 1-5%
of the sample onto the GC system. However, typical
ambient air concentrations of these compounds require a more
sensitive approach. The thermal desorption process, wherein
the entire sample is introduced into the analytical (GC/MS)
system fulfills this need for enhanced sensitivity.
5. Definitions
Definitions used in this document and any user prepared SOPs should
be consistent with ASTM 01356(6). All abbreviations and symbols
are defined with this document at the point of use.
6. INTERFERENCES
6.1 Only compounds having a similar mass spectrum and GC retention
time compared to the compound of interest will interfere in
the method. The most commonly encountered interferences are
structural isomers.
6.2 Contamination of the Tenax cartridge with the compound(s)
of interest is a commonly encountered problem in the method.
The user must be extremely careful in the preparation, storage,
and handling of the cartridges throughout the entire sampling
and analysis process to minimize this problem.
7. Apparatus
7.1 Gas Chromatograph/Mass Spectrometry system - should be capable
of subambient temperature programming. Unit mass resolution
or better up to 800 amu. Capable of scanning 30-440 amu region
every 0.5-1 second. Equipped with data system for instrument
control as well as data acquisition, processing and storage.
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TO!-4
7.2 Thermal Desorption Unit - Designed to accommodate Tenax
cartridges in use. See Figure 2a or b.
7.3 Sampling System - Capable of accurately and precisely
drawing an air flow of 10-500 ml/minute through the Tenax
cartridge. (See Figure 3a or b.)
7.4 Vacuum oven - connected to water aspirator vacuum supply.
7.5 Stopwatch
7.6 Pyrex disks - for drying Tenax.
7.7 Glass jar - Capped with Teflon-lined screw cap. For
storage of purified Tenax.
7.8 Powder funnel - for delivery of Tenax into cartridges.
7.9 Culture tubes - to hold individual glass Tenax cartridges.
7.10 Friction top can (paint can) - to hold clean Tenax cartridges.
7.11 Filter holder - stainless steel or aluminum (to accommodate
1 inch diameter filter). Other sizes may be used if desired.
(optional)
7.12 Thermometer - to record ambient temperature.
7.13 Barometer (optional).
7.14 Dilution bottle - Two-liter with septum cap for standards
preparation.
7.15 Teflon stirbar - 1 inch long.
7.16 Gas-tight glass syringes with stainless steel needles -
10-500 ul for standard injection onto GC/MS system..
7.17 Liquid micro!iter syringes - 5,50 ul for injecting neat
liquid standards into dilution bottle.
7.18 Oven - 60 + 5°C for equilibrating dilution flasks.
7.19 Magnetic stirrer.
7.20 Heating mantel.
7.21 Variac
7.22 Soxhlet extraction apparatus and glass thimbles - for purifying
Tenax.
7.23 Infrared lamp - for drying Tenax.
7.24 GC column - SE-30 or alternative coating, glass capillary or
fused silica.
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T01-5
7.25 Psychrometer - to determine ambient relative humidity.
(optional).
8. Reagents and Materials
8.1 Empty Tenax cartridges - glass or stainless steel (See
Figure la or b).
8.2 Tenax 60/80 mesh (2,6-diphenylphenylene oxide polymer),
8.3 Glasswool - silanized.
8.4 Acetone - Pesticide quality or equivalent.
8.5 Methanol - Pesticide quality, or equivalent.
8.6 Pentane - Pesticide quality or equivalent.
8.7 Helium - Ultra pure, compressed gas. (99.9999%)
8.8 Nitrogen - Ultra pure, compressed gas. (99.9999%)
8.9 Liquid nitrogen.
8.10 Polyester gloves - for handling glass Tenax cartridges.
8.11 Glass Fiber Filter - one inch diameter, to fit in filter holder.
(optional)
8.12 Perfluorotributylamine (FC-43).
8.13 Chemical Standards - Neat compounds of interest. Highest
purity available.
8.14 Granular activated charcoal - for preventing contamination of
Tenax cartridges during storage.
9. Cartridge Construction and Preparation
9.1 Cartridge Design
9.1.1 Several cartridge designs have been reported in the
literature (1-3). The most common (1) is shown in
Figure la. This design minimizes contact of the
sample with metal surfaces, which can lead to
decomposition in certain cases. However, a
disadvantage of this design is the need to rigorously
avoid contamination of the outside portion of the
cartridge since the entire surface is subjected to the
purge gas stream during the desorption porcess.
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T01-6
Clean polyester gloves must be worn at all times
when handling such cartridges and exposure of the
open cartridge to ambient air must be minimized.
9.1.2 A second common type of design (3) is shown in
Figure Ib. While this design uses a metal (stainless
steel) construction, it eliminates the need to avoid
direct contact with the exterior surface since only
the interior of the cartridge is purged.
9.1.3 The thermal desorption module and sampling system
must be selected to be compatible with the particular
cartridge design chosen. Typical module designs
are shown in Figures 2a and b. These designs are
suitable for the cartridge designs shown in Figures
la and Ib, respectively.
9.2 Tenax Purification
9.2.1 Prior to use the Tenax resin is subjected to a
series of solvent extraction and thermal treatment
steps. The operation should be conducted in an area
where levels of volatile organic compounds (other than
the extraction solvents used) are minimized.
9.2.2 All glassware used in Tenax purification as well as
cartridge materials should be thoroughly cleaned by
water rinsing followed by an acetone rinse and dried
in an oven at 250°C.
9.2.3 Bulk Tenax is placed in a glass extraction thimble
and held in place with a plug of clean glasswool.
The resin is then placed in the soxhlet extraction
apparatus and extracted sequentially with methanol
and then pentane for 16-24 hours (each solvent) at
approximately 6 cycles/hour. Glasswool for cartidge
preparation should be cleaned in the same manner as
Tenax.
9.2.4 The extracted Tenax is immediately placed in an open
glass dish and heated under an infrared lamp for two
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TO!-7
hours in a hood. Care must be exercised to avoid
over heating of the Tenax by the infrared lamp.
The Tenax is then placed in a vacuum oven (evacuated
using a water aspirator) without heating for one hour.
An inert gas (helium or nitrogen) purge of 2-3
ml/minute is used to aid in the removal of solvent
vapors. The oven temperature is then increased to
110°C, maintaining inert gas flow and held for one
hour. The oven temperature control is then shut
off and the oven is allowed to cool to room temperature.
Prior to opening the oven, the oven is slightly
pressurized with nitrogen to prevent contamination
with ambient air. The Tenax is removed from the oven
and sieved through a 40/60 mesh sieve (acetone rinsed
and oven dried) into a clean glass vessel. If the Tenax
is not to be used immediately for cartridge preparation
it should be stored in a clean glass jar having a
Teflon-lined screw cap and placed in a desiccator.
9.3 Cartridge Preparation and Pretreatment
9.3.1 All cartridge materials are pre-cleaned as described
in Section 9.2.2. If the glass cartridge design shown
in Figure la is employed all handling should be
conducted wearing polyester gloves.
9.3.2 The cartridge is packed by placing a 0.5-lcm glass-
wool plug in the base of the cartridge and then
filling the cartridge to within approximately 1 cm
of the top. A 0.5-lcm glasswool plug is placed in
the top of the cartridge.
9.3.3 The cartridges are then thermally conditioned by
heating for four hours at 270°C under an inert gas
(helium) purge (100 - 200 ml/min).
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TO!-8
9.3.4 After the four hour heating period the cartridges
are allowed to cool. Cartridges of the type shown
in Figure la are immediately placed (without cooling)
in clean culture tubes having Teflon-lined screw caps
with a glasswool cushion at both the top and the bottom.
Each tube should be shaken to ensure that the cartridge
is held firmly in place. Cartridges of the type shown
in Figure Ib are allowed to cool to room temperature under
inert gas purge and are then closed with stainless steel
plugs.
9.3.5 The cartridges are labeled and placed in a tightly
sealed metal can (e.g. paint can or similar friction
top container). For cartridges of the type shown
in Figure la the culture tube, not the cartridge,is
labeled.
9.3.6 Cartridges should be used for sampling within 2 weeks
after preparation and analyzed within two weeks after
sampling. If possible the cartridges should be stored
at -20°C in a clean freezer (i.e. no solvent extracts
or other sources of volatile organics contained in the
freezer).
10. Sampling
10.1 Flow rate and Total Volume Selection
10.1.1 Each compound has a characteristic retention volume
(liters of air per gram of adsorbent) which must not
be exceeded. Since the retention volume is a function
of temperature, and possibly other sampling variables,
one must include an adequate margin of safety to
ensure good collection efficiency. Some considerations
and guidance in this regard are provided in a recent
report (5). Approximate breakthrough volumes at 38°C
(100°F) in liters/gram of Tenax are provided in Table 1.
These retention volume data are supplied only as rough
guidance and are subject to considerable variability,
depending on cartridge design as well as sampling
parameters and atmospheric conditions.
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T01-9
10.1.2 To calculate the maximum total volume of air which
can be sampled use the following equation:
VMAX = vbxw
1.5
where
VMAX is tne calculated maximum total volume in liters.
Vfo is the breakthrough volume for the least retained
compound of interest (Table 1) in liters per gram
of Tenax.
W is the weight of Tenax in the cartridge, in grams.
1.5 is a dimensionless safety factor to allow for
variability in atmospheric conditions. This factor
is appropriate for temperatures in the range of
25-30°C. If higher temperatures are encountered the
factor should be increased (i.e. maximum total volume
decreased).
10.1.3 To calculate maximum flow rate use the following
equation:
V
n MAX v 1000
QMAX = -t— x IUUU
where
QMAX is *ne calculated maximum flow rate in milli-
leters per minute.
t is the desired sampling time in minutes. Times
greater than 24 hours (1440 minutes) generally
are unsuitable because the flow rate required
is too low to be accurately maintained.
10.1.4 The maximum flow rate QMAX should yield a linear flow
velocity of 50-500 cm/minute. Calculate the linear
velocity corresponding to the maximum flow rate
using the following equation:
B = QMAX
irr
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T01-10
where
B is the calculated linear flow velocity in
centimeters per minute.
r is the internal radius of the cartridge in
centimeters.
If B is greater than 500 centimeters per minute
either the total sample volume (VMAX) should be
reduced or the sample flow rate (QMAX) should be
reduced by increasing the collection time. If B is
less than 50 centimeters per minute the sampling rate
(QMAX) should be increased by reducing the sampling
time. The total sample value (VMAX) cannot be
increased due to component breakthrough.
10.1.4 The flow rate calculated as described above defines
the maximum flow rate allowed. In general, one should
collect additional samples in parallel, for the same
time period but at lower flow rates. This practice
yields a measure of quality control and is further
discussed in the literature (5). In general, flow
rates 2 to 4 fold lower than the maximum flow rate
should be employed for the parallel samples. In
all cases a constant flow rate should be achieved
for each cartridge since accurate integration of the
analyte concentration requires that the flow be
constant over the sampling period.
10.2 Sample Collection
10.2.1 Collection of an accurately known volume of air
is critical to the accuracy of the results. For
this reason the use of mass flow controllers,
rather than conventional needle valves or orifices
is highly recommended, especially at low flow
velocities (e.g. less than 100 milliliters/minute).
Figure 3a illustrates a sampling system utilizing
mass flow controllers. This system readily allows
for collection of parallel samples. Figures 3b
shows a commercially available system based on
needle valve flow controllers.
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Toi-n
10.2.2 Prior to sample collection insure that the sampling
flow rate has been calibrated over a range including
the rate to be used for sampling, with a "dummy"
Tenax cartridge in place. Generally calibration
is accomplished using a soap bubble flow meter
or calibrated wet test meter. The flow calibration
device is connected to the flow exit, assuming
the entire flow system is sealed. ASTM Method
D3686 describes an appropriate calibration scheme,
not requiring a sealed flow system downstream
of the pump.
10.2.3 The flow rate should be checked before and after
each sample collection. If the sampling interval
exceeds four hours the flow rate should be checked
at an intermediate point during sampling as well.
In general, a rotameter should be included, as
showed in Figure 3b, to allow observation of the
sampling flow rate without disrupting the sampling
process.
10.2.4 To collect an air sample the cartridges are removed
from the sealed container just prior to initiation
of the collection process. If glass cartridges
(Figure la) are employed they must be handled
only with polyester gloves and should not contact
any other surfaces.
10.2.5 A particulate filter and holder are placed on
the inlet to the cartridges and the exit end
of the cartridge is connected to the sampling
apparatus. In many sampling situations the use
of a filter is not necessary if only the total
concentration of a component is desired. Glass
cartridges of the type shown in Figure la are
connected using teflon ferrules and Swagelok
(stainless steel or teflon) fittings. Start the
pump and record the following parameters on an
appropriate data sheet (Figure 4): data, sampling
location, time, ambient temperature, barometric
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T01-12
pressure, relative humidity, dry gas meter reading
(if applicable) flow rate, rotameter reading (if
applicable), cartridge number and dry gas meter
serial number.
10.2.6 Allow the sampler to operate for the desired time,
periodically recording the variables listed above.
Check flow rate at the midpoint of the sampling
interval if longer than four hours.
At the end of the sampling period record the
parameters listed in 10.2.5 and check the flow
rate and record the value. If the flows at the
beginning and end of the sampling period differ
by more than 10% the cartridge should be marked
as suspect.
10.2.7 Remove the cartridges (one at a time) and place
in the original container (use gloves for glass
cartridges). Seal the cartridges or culture tubes
in the friction-top can containing a layer of
charcoal and package for immediate shipment to
the laboratory for analysis. Store cartridges
at reduced temperature (e.g. - 20°C) before analysis
if possible to maximize storage stability.
10.2.8 Calculate and record the average sample rate for
each cartridge according to the following equation:
Q. Qi + Q2 + ---QN
A " N
where
Q/\ = Average flow rate in ml/minute.
Q], 0.2, QN= Flow rates determined at
beginning, end, and immediate points
during sampling.
N = Number of points averaged.
10.2.9 Calculate and record the total volumetric flow for
each cartridge using the following equation:
1000
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T01-13
where
Vm = Total volume sampled in liters at measured
temperature and pressure,
T2 = Stop time.
T] = Start time.
T = Sampling time = T£ - T], minutes
10.2.10 The total volume (Vs) at standard conditions,
25°C and 760 rnrnHg, is calculated from the
following equation:
'm x 76o * 273 + tA
where
P/\ = Average barometric pressure, mrnHg
t/\ = Average ambient temperature, °C.
11. 6C/MS Analysis
11.1 Instrument Set-up
11.1.1 Considerable variation from one laboratory to
another is expected in terms of instrument configuration.
Therefore each laboratory must be responsible
for verifying that their particular system yields
satisfactory results. Section 14 discusses specific
performance criteria which should be met.
11.1.2 A block diagram of the typical GC/MS system
required for analysis of Tenax cartridges is
depicted in Figure 5. The operation of such
devices is described in 11.2.4. The thermal
desorption module must be designed to accommodate
the particular cartridge configuration. Exposure
of the sample to metal surfaces should be
minimized and only stainless steel, or nickel metal
surfaces should be employed.
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T01-14
The volume of tubing and fittings leading from
the cartridge to the GC column must be minimized
and all areas must be well-swept by helium carrier
gas.
11.1.3 The GC column inlet should be capable of being
cooled to -70°C and subsequently increased rapidly
to approximately 30°C. This can be most readily
accomplished using a GC equipped with subambient
cooling capability (liquid nitrogen) although
other approaches such as manually cooling the
inlet of the column in liquid nitrogen may be
acceptable.
11.1.4 The specific GC column and temperature program
employed will be dependent on the specific compounds
of interest. Appropriate conditions are described
in the literature (1-3). In general a nonpolar
stationary phase (e.g. SE-30, OV-1) temperature
programmed from 30°C to 200°C at 8°/minute will
be suitable. Fused silica bonded phase columns
are preferable to glass columns since they are
more rugged and can be inserted directly into
the MS ion source, thereby eliminating the need
for a GC/MS transfer line.
11.1.5 Capillary column dimensions of 0.3 mm ID and 50
meters long are generally appropriate although
shorter lengths may be sufficient in many cases.
11.1.6 Prior to instrument calibration or sample analysis
the GC/MS system is assembled as shown in Figure
5. Helium purge flows (through the cartridge)
and carrier flow are set at approximately 10 ml/
minute and 1-2 ml/minute respectively. If applicable,
the injector sweep flow is set at 2-4 ml/minute.
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T01-15
11.1.7 Once the column and other system components are
assembled and the various flows established the
column temperature is increased to 250°C for
approximately four hours (or overnight if desired)
to condition the column.
11.1.8 The MS and data system are set according to the
manufacturer's instructions. Electron impact
ionization (70eV) and an electron multiplier gain
of approximately 5 x 10^ should be employed.
Once the entire GC/MS system has been setup the
system is calibrated as described in Section 11.2.
The user should prepare a detailed standard
operating procedure (SOP) describing this process
for the particular instrument being used.
11.2 Instrument Calibration
11.2.1 Tuning and mass standarization of the MS system
is performed according to manufacturer's instructions
and relevant information from the user prepared
SOP. Perf1uorotributyl amine should generally
be employed for this purpose. The material
is introduced directly into the ion source
through a molecular leak. The instrumental
parameters (e.g. lens voltages, resolution,
etc.) should be adjusted to give the relative
ion abundances shown in Table 2 as well as
acceptable resolution and peak shape. If
these approximate relative abundances cannot
be achieved, the ion source may require cleaning
according to manufacturer's instructions.
In the event that the user's instrument cannot
achieve these relative ion abundances, but
is otherwise operating properly, the user
may adopt another set of relative abundances
as performance criteria.
-------
T01-16
However, these alternate values must be repeatable
on a day-to-day basis.
11.2.2 After the mass standarization and tuning process
has been completed and the appropriate values
entered into the data system the user should
then calibrate the entire system by introducing
known quantities of the standard components
of interest into the system. Three alternate
procedures may be employed for the calibration
process including 1) direct syringe injection
of dilute vapor phase standards, prepared
in a dilution bottle, onto the GC column, 2)
Injection of dilute vapor phase standards
into a carrier gas stream directed through the
Tenax cartridge, and 3) introduction of permeation
or diffusion tube standards onto a Tenax cartridge.
The standards preparation procedures for each
of these approaches are described in Section
13. The following paragraphs describe the
instrument calibration process for each of
these approaches.
11.2.3 If the instrument is to be calibrated by direct
injection of a gaseous standard, a standard
is prepared in a dilution bottle as described
in Section 13.1. The GC column is cooled
to -70°C (or, alternately, a portion of the
column inlet is manually cooled with liquid
nitrogen). The MS and data system is set
up for acquisition as described in the relevant
user SOP. The ionization filament should be turned
off during the initial 2-3 minutes of the run to
allow oxygen and other highly volatile components
to elute. An appropriate volume (less than 1 ml)
of the gaseous standard is injected onto the GC
system using an accurately calibrated gas tight syringe.
-------
T01-17
The system clock is started and the column is
maintained at -70°C (or liquid nitrogen inlet cooling)
for 2 minutes. The column temperature is rapidly
increased to the desired initial temperature (e.g. 30°C).
The temperature program is started at a consistent
time (e.g. four minutes) after injection. Simultaneously
the ionization filament is turned on and data acquisition
is initiated. After the last component of interest has
eluted acquisiton is terminated and the data is processed
as described in Section 11.2.5. The standard injection
process is repeated using different standard volumes as
desired.
11.2.4 If the system is to be calibrated by analysis of
spiked Tenax cartridges a set of cartridges is
prepared as described in Sections 13.2 or 13.3.
Prior to analysis the cartridges are stored as
described in Section 9.3. If glass cartridges (Figure la)
are employed care must be taken to avoid direct
contact, as described earlier. The GC column is
cooled to -70°C, the collection loop is immersed in
liquid nitrogen and the desorption module is
maintained at 250°C. The inlet valve is placed in the
desorb mode and the standard cartridge is placed in
the desorption module, making certain that no leakage
of purge gas occurs. The cartridge is purged
for 10 minutes and then the inlet valve is placed in
the inject mode and the liquid nitrogen source removed
from the collection trap. The GC column is maintained
at -70°C for two minutes and subsequent steps are as
described in 11.2.3. After the process is complete the
cartridge is removed from the desorption module and
stored for subsequent use as described in Section 9.3.
-------
T01-18
11.2.5 Data processing for instrument calibration involves
determining retention times, and integrated characteristic
ion intensities for each of the compounds of interest.
In addition, for at least one chromatographic run,the
individual mass spectra should be inspected and
compared to reference spectra to ensure proper
instrumental performance. Since the steps involved
in data processing are highly instrument specific, the
user should prepare a SOP describing the process for
individual use. Overall performance criteria for
instrument calibration are provided in Section 14. If
these criteria are not achieved the user should refine
the instrumental parameters and/or operating
procedures to meet these criteria.
11.3 Sample Analysis
11.3.1 The sample analysis process is identical to that
described in Section 11.2.4 for the analysis of standard
Tenax cartridges.
11.3.2 Data processing for sample data generally involves
1) qualitatively determining the presence or absence
of each component of interest on the basis of a set
of characteristic ions and the retention time using
a reverse^search software routine, 2) quantification
of each identified component by integrating the intensity
of a characteristic ion and comparing the value to
that of the calibration standard, and 3) tentative
identification of other components observed using a
forward (library) search software routine. As for
other user specific processes, a SOP should be prepared
describing the specific operations for each individual
laboratory.
-------
TO!-19
12. Calculations
12.1 Calibration Response Factors
12.1.1 Data from calibration standards is used to calculate
a response factor for each component of interest.
Ideally the process involves analysis of at least
three calibration levels of each component during a
given day and determination of the response
factor (area/nanogram injected) from the linear
least squares fit of a plot of nanograms injected
versus area (for the characteristic ion).
In general quantities of component greater
than 1000 nanograms should not be injected
because of column overloading and/or MS response
non linearity.
12.1.2 In practice the daily routine may not always
allow analysis of three such calibration standards.
In this situation calibration data from consecutive
days may be pooled to yield a response factor,
provided that analysis of replicate standards
of the same concentration are shown to agree
within 20% on the consecutive days. One standard
concentration, near the midpoint of the analytical
range of interest, should be chosen for injection
every day to determine day-to-day response
reproducibility.
12.1.3 If substantial nonlinearity is present in
the calibration curve a nonlinear least squares
fit (e.g. quadratic) should be employed.
This process involves fitting the data to
the following equation:
Y = A + BX + CX2
where
Y = peak area
X = quantity of component, nanograms
A,B, and C are coefficients in the equation
-------
TO 1-20
12.2 Analyte Concentrations
12.2.1
where
12.2.2
12.2.3
where
Analyte quantities on a sample cartridge are calculated
from the following equation:
YA = A + BXA + CXA
YA is the area of the analyte characteristic ion for
the sample cartridge.
XA is the calculated quantity of analyte on the sample
cartridge, in nanograms.
A,B, and C are the coefficients calculated from the
calibration curve described in Section 12.1.3.
If instrumental response is essentially linear over the
concentration range of interest a linear equation
(C=0 in the equation above) can be employed.
Concentration of analyte in the original air sample is
calculated from the following equation:
r XA
CA is the calculated concentration of analyte in
nanograms per liter.
Vs and X. are as previously defined in Section
10.2.10 and 12.2.1, respectively.
13. Standard Preparation
13.1 Direct Injection
13.1.1 This process involves preparation of a dilution
bottle containing the desired concentrations
of compounds of interest for direct injection
onto the GC/MS system.
-------
T01-21
13.1.2 Fifteen three-millimeter diameter glass beads
and a one-inch Teflon stirbar are placed in a
clean two-liter glass septum capped bottle and
the exact volume is determined by weighing the
bottle before and after filling with deionized water.
The bottle is then rinsed with acetone and dried at 200°C.
13.1.3 The amount of each standard to be injected into the
vessel is calculated from the desired injection quantity
and volume using the following equation:
WT _ -
T "vl
where
Wj is the total quantity of analyte to be injected
into the bottle in milligrams
Wj is the desired weight of analyte to be injected
onto the GC/MS system or spiked cartridge in
nanograms
Vi is the desired GC/MS or cartridge injection
volume (should not exceed 500) in microliters.
VB is total volume of dilution bottle determined
in 13.1.1, in liters.
13.1.4 The volume of the neat standard to be injected
into the dilution bottle is determined using
the following equation:
WT
where
Vj is the total volume of neat liquid to be injected
in microliters.
d is the density of the neat standard in grams per
milliliter.
-------
T01-22
13.1.6 The bottle is placed in a 60°C oven for at
least 30 minutes prior to removal of a vapor
phase standard.
13.1.7 To withdraw a standard for GC/MS injection
the bottle is removed from the oven and stirred
for 10-15 seconds. A suitable gas-tight microber
syring warmed to 60°C, is inserted through
the septum cap and pumped three times slowly.
The appropriate volume of sample (approximately 25%
larger than the desired injection volume) is drawn
into the syringe and the volume is adjusted to the
exact value desired and then immediately injected
over a 5-10 seconds period onto the GC/MS system as
described in Section 11.2.3.
13.2 Preparation of Spiked Cartridges by Vapor Phase Injection
13.2.1 This process involves preparation of a dilution
bottle containing the desired concentrations
of the compound(s) of interest as described
in 13.1 and injecting the desired volume of
vapor into a flowing inert gas stream directed
through a clean Tenax cartridge.
13.2.2 A helium purge system is assembled wherein
the helium flow 20-30 mL/minute is passed
through a stainless steel Tee fitted with
a septum injector. The clean Tenax cartridge
is connected downstream of the tee using
appropriate Swagelok fittings. Once the cartridge
is placed in the flowing gas stream the appropriate
volume vapor standard, in the dilution bottle,
is injected through the septum as described in
13.1.6. The syringe is flushed several times
by alternately filling the syringe with carrier
gas and displacing the contents into the flow
stream, without removing the syringe from the septum.
Carrier flow is maintain through the cartridge for
approximately 5 minutes after injection.
-------
TO!-23
13.3 Preparation of Spiked Traps Using Permeation or Diffusion
tubes
13.3.1 A flowing stream of inert gas containing known
amounts of each compound of interest is generated
according to ASTM Method 03609(6). Note that
a method of accuracy maintaining temperature
within + 0.1°C is required and the system
generally must be equilibrated for at least
48 hours before use.
13.3.2 An accurately known volume of the standard
gas stream (usually 0.1-1 liter) is drawn
through a clean Tenax cartridge using the
sampling system described in Section 10.2.1,
or a similar system. However, if mass flow
controllers are employed they must be calibrated
for the carrier gas used in Section 13.3.1
(usually nitrogen). Use of air as the carrier
gas for permeation systems is not recommended,
unless the compounds of interest are known
to be highly stable in air.
13.3.3 The spiked cartridges are then stored or immediately
analyzed as in Section 11.2.4.
14. Performance Criteria and Quality Assurance
This section summarizes quality assurance (QA) measures and
provides guidance concerning performance criteria which should be
achieved within each laboratory. In many cases the specific
QA procedures have been described within the appropriate section
describing the particular activity (e.g. parallel sampling).
-------
TO!-24
14.1 Standard Opreating Procedures (SOPs)
14.1.1 Each user should generate SOPs describing the
following activities as they are performed
in their laboratory:
1) assembly, calibration, and operation of
the sampling system,
2) preparation, handling and storage of Tenax
cartridges,
3) assembly and operation of GC/MS system including
the thermal desorption apparatus and data
system, and
4) all aspects of data recording and processing.
14.1.2 SOPs should provide specific stepwise instructions
and should be readily available to, and understood
by the laboratory personnel conducting the
work.
14.2 Tenax Cartridge Preparation
14.2.1 Each batch of Tenax cartridges prepared (as
described in Section 9) should be checked for
contamination by analyzing one cartridge immediately
after preparation. While analysis can be accomplished
by GC/MS, many laboratories may chose to use
GC/FID due to logistical and cost considerations.
14.2.2 Analysis by GC/FID is accomplished as described
for GC/MS (Section 11) except for use of FID
detection.
-------
TO!-25
14.2.3 While acceptance criteria can vary depending
on the components of interest, at a minimum
the clean cartridge should be demonstrated
to contain less than one fourth of the minimum
level of interest for each component. For
most compounds the blank level should be less
than 10 nanograms per cartridge in order to
be acceptable. More rigid criteria may be
adopted, if necessary, within a specific laboratory.
If a cartridge does not meet these acceptance
criteria the entire lot should be rejected.
14.3 Sample Collection
14.3.1 During each sampling event at least one clean
cartridge will accompany the samples to the
field and back to the laboratory, without being
used for sampling, to serve as a field blank.
The average amount of material found on the
field blank cartridge may be subtracted from
the amount found on the actual samples. However,
if the blank level is greater than 25% of the
sample amount, data for that component must
be identified as suspect.
14.3.2 During each sampling event at least one set
of parallel samples (two or more samples collected
simultaneously) will be collected, preferably
at different flow rates as described in Section
10.1. If agreement between parallel samples
is not generally within + 25/S the user should
collect parallel samples on a much more frequent
basis (perhaps for all sampling points). If
a trend of lower apparent concentrations with
increasing flow rate is observed for a set
-------
TOT-26
of parallel samples one should consider using
a reduced flow rate and longer sampling interval
if possible. If this practice does not improve
the reproducibility further evaluation of the
method performance for the compound of interest
may be required.
14.3.3 Backup cartridges (two cartridges in series)
should be collected with each sampling event.
Backup cartridges should contain less than
20% of the amount of components of interest
found in the front cartridges, or be equivalent
to the blank cartridge level, whichever is
greater. The frequency of use of backup cartridges
should be increased if increased flow rate
is shown to yield reduced component levels
for parallel sampling. This practice will
help to identify problems arising from breakthrough
of the component of interest during sampling.
14.4 GC/MS Analysis
14.4.1 Performance criteria for MS tuning and mass
calibration have been discussed in Section
11.2 and Table 2. Additional criteria may
be used by the laboratory if desired. The
following sections provide performance guidance
and suggested criteria for determining the
acceptability of the GC/MS system.
14.4.2 Chromatographic efficiency should be evaluated
using spiked Tenax cartridges since this practice
tests the entire system. In general a reference
compound such as perfluorotoluene should be
spiked onto a cartridge at the 100 nanogram
level as described in Section 13.2 or 13.3.
The cartridge is then analyzed by GC/MS as
-------
T01-27
described in Section 11.4. The perfluorotoluene (or
other reference compound) peak is then plotted on an
expanded time scale so that its width at 10% of the
peak can be calculated, as shown in Figure 6. The
width of the peak at 10% height should not exceed
10 seconds. More stringent criteria may be required
for certain applications. The assymmetry factor
(See Figure 6) should be between 0.8 and 2.0. The
assymmetry factor for any polar or reactive compounds
should be determined using the process described above.
If peaks are observed that exceed the peak width or
assymmetry factor criteria above, one should inspect
the entire system to determine if unswept zones or
cold spots are present in any of the fittings and
is necessary. Some laboratories may chose
to evaluate column performance separately by
direct injection of a test mixture onto the
GC column. Suitable schemes for column evaluation
have been reported in the literature (7).
Such schemes cannot be conducted by placing
the substances onto Tenax because many of
the compounds (e.g. acids, bases, alcohols)
contained in the test mix are not retained,
or degrade, on Tenax.
14.4.3 The system detection limit for each component
is calculated from the data obtained for
calibration standards. The detection limit
is defined as
DL = A + 3.3S
-------
T01-28
where
DL is the calculated detection limit in
nanograms injected.
A is the intercept calculated in Section
12.1.1 or 12.1.3.
S is the standard deviation of replicate
determinations of the lowest level standard
(at least three such determinations are
required.
In general the detection limit should be 20
nanograms or less and for many applications
detection limits of 1-5 nanograms may be required.
The lowest level standard should yield a signal
to noise ratio, from the total ion current response,
of approximately 5.
14.4.4 The relative standard deviation for replicate
analyses of cartridges spiked at approximately
10 times the detection limit should be 20%
or less. Day to day relative standard deviation
should be 25% or less.
14.4.5 A useful performance evaluation step is the
use of an internal standard to track system
performance. This is accomplished by spiking
each cartridge, including blank, sample, and
calibration cartridges with approximately 100
nanograms of a compound not generally present
in ambient air (e.g. perfluorotoluene). The
integrated ion intensity for this compound
helps to identify problems with a specific
sample. In general the user should calculate
the standard deviation of the internal standard
response for a given set of samples analyzed
under identical tuning anc1 calibration conditions.
Any sample giving a value greater than _+ 2
standard deviations from the mean (calculated
-------
T01-31
TABLE 1. RETENTION VOLUME ESTIMATES FOR COMPOUNDS ON TENAX
ESTIMATED RETENTION VOLUME AT
COMPOUND 100°F (38°C)-LITERS/GRAM
Benzene 19
Toluene 97
Ethyl Benzene 200
Xylene(s) -v 200
Cumene 440
n-Heptane 20
1-Heptene 40
Chloroform 8
Carbon Tetrachloride 8
1,2-Dichloroethane 10
1,1,l-Trichloroethane 6
Tetrechloroethylene 80
Trichloroethylene 20
1,2-Dichloropropane 30
1,3-Dichloropropane 90
Chlorobenzene 150
Bromoform 100
Ethylene Dibromide 60
Bromobenzene 300
-------
TO!-32
TABLE 2. SUGGESTED PERFORMANCE CRITERIA FOR RELATIVE
ION ABUNDANCES FROM FC-43 MASS CALIBRATION
% RELATIVE
M/E ABUNDANCE
51 1.8+0.5
69 100
100 12.0 + 1.5
119 12.0 + 1.5
131 35.0 + 3.5
169 3.0 + 0.4
219 24.0 + 2.5
264 3.7 + 0.4
314 0.25 + 0.1
-------
TO!-29
excluding that particular sample) should be
identified as suspect. Any marked change in
internal standard response may indicate a need
for instrument recalioration.
-------
T01-30
REFERENCES
1. Krost, K. J., Pellizzari, E. D., Walburn, S. 6., and Hubbard, S. A.,
"Collection and Analysis of Hazardous Organic Emissions",
Analytical Chemistry. 54, 810-817, 1982.
2. Pellizzari, E. 0. and Bunch, J. E., "Ambient Air Carcinogenic Vapors-
Improved Sampling and Analytical Techniques and Field Studies",
EPA-600/2-79-081, U.S. Environmental Protection Agency, Research
Triangle Park, North Carolina, 1979.
3. Kebbekus, B. B. and Bozzelli, J. W., "Collection and Analysis of
Selected Volatile Organic Compounds in Ambient Air", Proc. Air
Pollution Control Assoc., Paper No. 82-65.2. Air Poll. Control
Assoc., Pittsburgh, Pennsylvania, 1982.
4. Riggin, R. M., "Technical Assistance Document for Sampling and
Analysis of Toxic Organic Compounds in Ambient Air", EPA-600/
4-83-027, U.S. Environmental Protection Agency, Research Triangle
Park, North Carolina, 1983.
5. Walling, J. F., Berkley, R. E., Swanson, D. H., and Toth, F. J.
"Sampling Air for Gaseous Organic Chemical-Applications to Tenax",
EPA-600/7-54-82-059, U.S. Environmental Protection Agency, Research
Triangle Park, North Carolina, 1982.
6. Annual Book of ASTM Standards, Part 11.03, "Atmospheric Analysis",
American Society for Testing and Material, Philadelphia,
Pennsylvania.
7. Grob, K., Jr., Grob, 6.,-and Grob, K., "Comprehensive Standardized
Quality Test for Glass Capillary Columns", J. Chromatog., 156,
1-20, 1978.
-------
T01-33
Tenax
~1.5 Grams (6 cm Bed Depth)
• Glass Wool Plugs
(0.5 cm Long)
Glass Cartridge
(13.5 mm OD x
100 mm Long)
idae A
.(a) Glass Cartridge
1/2" to
1/8"
Reducing
Union
Glass Wool
Plugs
(0.5 cm Long)
\
1/8" End Cap,
Tenax
~1.5 Grams (7 cm Bed Depth)
(b) Metal Cartridge
Metal Cartridge
(12.7 mm OD x
100 mm Long)
FIGURE 1. TENAX CARTRIDGE DESIGNS
-------
T01-34
Teflon
Compression
Seal
Purge
Gas
Cavity for •
Tenax
Cartridge
Latch for
Compression
Seal
Effluent to
6-Port Valve
To GC/MS
Liquid
Nitrogen
Coolant
(a) Glass Cartridges (Compression Fit)
Purge
Swagelok
End Fittings
Tenax
Trap
z
Heated
Block
To GC/MS
Vent
Liquid
Nitrogen
Coolant
(b) Metal Cartridges (Swagelok Fittings)
FIGURE 2. TENAX CARTRIDGE DESORPTION MODULES
-------
TO!-35
D
Vent
Couplings
to Connect
Tenax
Cartridges
(a) Mass Flow Control
Rotometer
Vent
Dry
Test
Meter
V
Pump
Coupling to
Connect Tenax
Cartridge
Needle
Valve
(b) Needle Valve Control
FIGURE 3. TYPICAL SAMPLING SYSTEM CONFIGURATIONS
-------
TOT - 36
SAMPLING DATA SHEET
(One Sample Per Data Sheet)
PROJECT:
SITE:
DATE(S) SAMPLED:
LOCATION:
TIME PERIOD SAMPLED:
OPERATOR:
INSTRUMENT MODEL N0:_
PUMP SERIAL NO:
SAMPLING DATA
CALIBRATED BY:
Sample Number:
Start Time:
Stop Time:
Time
1.
2.
3.
4.
N.
Dry Gas
Meter
Reading
Rotameter
Reading
Flow
Rate,*Q
ml /Min
Ambient
Temperature
°C
Barometric
Pressure,
mmHg
Relative
Humidity, %
Comments
Total Volume Data**
Vm = (Final - Initial) Dry Gas Meter Reading, or
- Ql + 0.2 + 0.3---QN x 1 ,
R1000 x (Sampling Time in Minutes)
Liters
Liters
* Flowrate from rotameter or soap bubble calibrator
(specify which).
** Use data from dry gas meter if available.
FIGURE 4. EXAMPLE SAMPLING DATA SHEET
-------
Purge
Gas
TO!-37
Thermal
Desorption
Chamber
6-Port High-Temperature
Valve
Capillary
Gas
Chromatograph
Mass
Spectrometer
Data
System
Carrier
Gas
Vent
Freeze Out Loop
Liquid
Nitrogen
Coolant
FIGURE 5. BLOCK DIAGRAM OF ANALYTICAL SYSTEM
-------
TO!-38
BC
Asymmetry Factor * —
Example Calculation:
Peak Height - DE = 100 mm
10% Peak Height - BD - 10 mm
Peak Width at 10% Peak Height - AC - 23 mm
AB • 11 mm
BC *12 mm
12
Therefore: Asymmetry Factor • — « 1.1
FIGURE 6. PEAK ASYMMETRY CALCULATION
-------
METHOD T02 Revision 1.0
April, 1984
METHOD FOR THE DETERMINATION OF VOLATILE ORGANIC COMPOUNDS IN
AMBIENT AIR BY CARBON MOLECULAR SIEVE ADSORPTION AND
GAS CHROMATOGRAPHY/MASS SPECTROMETRY (GC/MS)
1. Scope
1.1 This document describes a procedure for collection and
determination of selected volatile organic compounds
which can be captured on carbon molecular sieve (CMS)
adsorbents and determined by thermal desorption GC/MS
techniques.
1.2 Compounds which can be determined by this method are
nonpolar and nonreactive organics having boiling points
in the range -15 to +120°C. However, not all compounds
meeting these criteria can be determined. Compounds for
which the performance of the method has been documented
are listed in Table 1. The method may be extended to
other compounds but additional validation by the user
is required. This method has been extensively used in
a single laboratory. Consequently, its general applicability
has not been thoroughly documented.
2. Applicable Documents
2.1 ASTM Standards
D 1356 Definitions of Terms Related to Atmospheric Sampling
and Analysis.
E 355 Recommended Practice for Gas Chromatography Terms
and Relationships.
2.2 Other Documents
Ambient Air Studies (1,2).
U.S. EPA Technical Assistance
Document (3).
-------
T02-2
3. Summary of Method
3.1 Ambient air is drawn through a cartridge containing ^0.4
of a carbon molecular sieve (CMS) adsorbent. Volatile
organic compounds are captured on the adsorbent while
major inorganic atmospheric constituents pass through
(or are only partially retained). After sampling, the
cartridge is returned to the laboratory for analysis.
3.2 Prior to analysis the cartridge is purged with 2-3 liters of
pure, dry air (in the same direction as sample flow) to
remove adsorbed moisture.
3.3 For analysis the cartridge is heated to 350°-400°C, under
helium purge and the desorbed organic compounds are
collected in a specially designed cryogenic trap. The
collected organics are then flash evaporated onto a
capillary column GC/MS system (held at -70°C). The
individual components are identified and quantified during
a temperature programmed chromatographic run.
3.4 Due to the complexity of ambient air samples, only high
resolution (capillary column) GC techniques are
acceptable for most applications of the method.
4. Significance
4.1 Volatile organic compounds are emitted into the atmosphere
from a variety of sources including industrial and commercial
facilities, hazardous waste storage and treatment facilities,
etc. Many of these compounds are toxic; hence knowledge of
the concentration of such materials in the ambient atmosphere
is required in order to determine human health impacts.
4.2 Traditionally air monitoring methods for volatile organic
compounds have relied on carbon adsorption followed by
solvent desorption and GC analysis. Unfortunately, such
methods are not sufficiently sensitive for ambient air
monitoring, in most cases, because only a small portion of
-------
T02-3
the sample is injected onto the GC system. Recently on-line
thermal desorption methods, using organic polymeric adsorbents
such as Tenax® GC, have been used for ambient air monitoring.
The current method uses CMS adsorbents (e.g. Spherocarb®)
to capture highly volatile organics (e.g. vinyl chloride)
which are not collected on Tenax®. The use of on-line thermal
desorption GC/MS yields a sensitive, specific analysis
procedure.
5. Definitions
Definitions used in this document and any user prepared SOPs should
be consistent with ASTM D1356 (4). All abbreviations and symbols
are defined with this document at the point of use.
6. Interferences
6.1 Only compounds having a mass spectrum and GC retention
time similar to the compound of interest will interfere
in the method. The most commonly encountered interferences
are structural isomers.
6.2 Contamination of the CMS cartridge with the compound(s)
of interest can be a problem in the method. The user must
be careful in the preparation, storage, and handling of the
cartridges through the entire process to minimize contamination.
-------
T02-4
7. Apparatus
7.1 Gas Chromatograph/Mass Spectrometry system - must be capable
of subambient temperature programming. Unit mass resolution
to 800 amu. Capable of scanning 30-300 amu region every
0.5-0.8 seconds. Equipped with data system for instrument
control as well as data acquisition, processing and storage.
7.2 Thermal Desorption Injection Unit - Designed to accommodate
CMS cartridges in use (See Figure 3) and including cryogenic
trap (Figure 5) and injection valve (Carle Model 5621
or equivalent).
7.3 Sampling System - Capable of accurately and precisely
drawing an air flow of 10-500 ml/minute through the CMS
cartridge. (See Figure 2a or b.)
7.4 Dewar flasks - 500 mL and 5 liter.
7.5 Stopwatches.
7.6 Various pressure regulators and valves - for connecting
compressed gas cylinders to GC/MS system.
7.7 Calibration gas - In aluminum cylinder. Prepared by
user or vendor. For GC/MS calibration.
7.8 High pressure apparatus for preparing calibration gas
cylinders (if conducted by user). Alternatively, custom
prepared gas mixtures can be purchased from gas supply
vendors.
7.9 Friction top can (e.g. one-gallon paint can) - With layer
of activated charcoal to hold clean CMS cartridges.
7.. 10 Thermometer - to record ambient temperature.
7.11 Barometer (optional).
7.12 Dilution bottle - Two-liter with septum cap for standard
preparation.
7.13 Teflon stirbar - 1 inch long
7.14 Gas tight syringes - 10-500 u.1 for standard injection onto
GC/MS system and CMS cartridges.
7.15 Liquid microliter syringes - 5-50 ul for injecting neat
liquid standards into dilution bottle.
7.16 Oven - 60 + 5°C for equilibrating dilution bottle.
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7.17 Magnetic stirrer.
7.18 Variable voltage transformers - (120 V and 1000 VA) and
electrical connectors (or temperature controllers) to
heat cartridge and cryogenic loop.
7.19 Digital pyrometer - 30 to 500°C range.
7.20 Soap bubble flow meter - 1, 10 and 100 mL calibration
points.
7.21 Copper tubing (1/8 inch) and fittings for gas inlet lines.
7.22 GC column - SE-30 or alternative coating, glass capillary
or fused silica.
7.23 Psychrometer (optional).
7.24 Filter holder - stainless steel or aluminum (to accommodate
1 inch diameter filter). Other sizes may be used if
desired, (optional)
8. Reagents and Materials
8.1 Empty CMS cartridges - Nickel or stainless steel (See
Figure 1).
8.2 CMS Adsorbent, 60/80 mesh- Spherocarb® from Analabs Inc.,
or equivalent.
8.3 Glasswool - silanized.
8.4 Methylene chloride - pesticide quality, or equivalent.
8.5 Gas purifier cartridge for purge and GC carrier gas
containing charcoal, molecular sieves, and a drying
agent. Available from various chromatography supply
houses.
8.6 Helium - Ultra pure, (99.9999%) compressed gas.
8.7 Nitrogen - Ultra pure, (99.9999%) compressed gas.
8.8 Liquid nitrogen or argon (50 liter dewar).
8.9 Compressed air, if required - for operation of GC oven
door.
8.10 Perfluorotributyl amine (FC-43) for GC/MS calibration.
8.11 Chemical Standards - Neat compounds of interest. Highest
purity available.
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9. Cartridge Construction and Preparation
9.1 A suitable cartridge design in shown in Figure 1. Alternate
designs have been reported (1) and are acceptable, provided
the user documents their performance. The design shown in
Figure 1 has a built-in heater assembly. Many users may
choose to replace this heater design with a suitable
separate heating block or oven to simplify the cartridge
design.
9.2 The cartridge is assembled as shown in Figure 1 using
standard 0.25 inch O.D. tubing (stainless steel or nickel),
1/4 inch to 1/8 inch reducing unions, 1/8 inch nuts,
ferrules, and endcaps. These parts are rinsed with
methylene chloride and heated at 250°C for 1 hour prior
to assembly.
9.3 The thermocouple bead is fixed to the cartridge body, and
insulated with a layer of Teflon tape. The heater wire
(constructed from a length of thermocouple wire) is wound
around the length of the cartridge and wrapped with Teflon
tape to secure the wire in place. The cartridge is then
wrapped with woven silica fiber insulation (Zetex or
equivalent). Finally the entire assembly is wrapped with
fiber glass tape.
9.4 After assembly one end of the cartridge is marked with
a serial number to designate the cartridge inlet during
sample collection.
9.5 The cartridges are then packed with ^0.4 grams .of CMS
adsorbent. Glasswool plugs (MD.5 inches long) are placed
at each end of the cartridge to hold the adsorbent firmly
in place. Care must be taken to insure that no strands
of glasswool extend outside the tubing, thus causing
leakage in the compression endfittings. After loading the
endfittings (reducing unions and end caps) are tightened
onto the cartridge.
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9.6 The cartridges are conditioned for initial use by heating
at 400°C overnight (at least 16 hours) with a 100 mL/minute
purge of pure nitrogen. Reused cartridges need only to be
heated for 4 hours and should be reanalyzed before use to
ensure complete desorption of impurities.
9.7 For cartridge conditioning ultra-pure nitrogen gas is passed
through a gas purifier to remove oxygen.moisture and organic
contaminants. The nitrogen supply is connected to the
unmarked end of the cartridge and the flow adjusted to
^50 mL/minute using a needle valve. The gas flow from the
inlet (marked) end of the cartridge is vented to the atmosphere.
9.8 The cartridge thermocouple lead is connected to a pyrometer
and the heater lead is connected to a variable voltage
transformer (Variac) set at 0 V_. The voltage on the Variac
is increased to ^15 _V and adjusted over a 3-4 minute period
to stabilize the cartridge temperature at 380-400°C.
9.9 After 10-16 hours of heating (for new cartridges) the
Variac is turned off and the cartridge is allowed to cool
to ^30°C, under continuing nitrogen flow.
9.10 The exit end of the cartridge is capped and then the entire
cartridge is removed from the flow line and the other endcap
immediately installed. The cartridges are then placed in a
metal friction top (paint) can containing ^2 inches of gran-
ulated activated charcoal (to prevent contamination of the
cartridges during storage) in the bottom, beneath a retaining
screen. Clean paper tissues (e.g. Kimwipes ) are placed in
can to avoid damage to the cartridges during shipment.
9.11 Cartridges are stored in the metal can at all times except
when in use. Adhesives initially present in the cartridge
insulating materials are "burnt off" during initial condition-
ing. Therefore, unconditioned cartridges should not be placed
in the metal can since they may contaminate the other
cartridges.
9.12 Cartridges are conditioned within two weeks of use. A blank
from each set of cartridges is analyzed prior to use in field
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sampling. If an acceptable blank level is achieved, that
batch of cartridges (including the cartridge serving as the
blank) can be used for field sampling.
10. Sampling
10.1 Flow Rate and Total Volume Selection
10.1.1 Each compound has a characteristic retention
volume (liters of air per unit weight of
adsorbent). However, all of the compounds listed
in Table 1 have retention volumes (at 37°C) in
excess of 100 liters/cartridge (0.4 gram CMS
cartridge) except vinyl chloride for which the
value is ^30 liters/cartridge. Consequently, if
vinyl chloride or similarly volatile compounds are
of concern the maximum allowable sampling volume
is approximately 20 liters. If such highly volatile
compounds are not of concern, samples as large as
100 liters can be collected.
10.1.2 To calculate the maximum allowable sampling flow
rate the following equation can be used:
QMax =
where
QM is the calculated maximum sampling
rate in mL/minute.
t is the desired sampling time in minutes.
Vu is the maximum allowable total volume
Max
based on the discussion in 10.1.1.
10.1.3 For the cartridge design shown in Figure 1
should be between 20 and 500 mL/minute. If
lies outside this range the sampling time or total
sampling volume must be adjusted so that this
criterion is achieved.
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10.1.4 The flow rate calculated in 10.1.3 defines the
maximum allowable flow rate. In general, the
user should collect additional samples in parallel,
at successive 2- to 4-fold lower flow rates. This
practice serves as a quality control procedure to
check on component breakthrough and related sampling
and adsorption problems, and is further discussed
in the literature (5).
10.2 Sample Collection
10.2.1 Collection of an accurately known volume of air
is critical to the accuracy of the results. For
this reason the use of mass flow controllers, rather
than conventional needle valves or orifices is highly
recommended, especially at low flow rates (e.g. less
than 100 milliliters/minute). Figure 2a illustrates
a sampling system based on mass flow controllers
which readily allows for collection of parallel samples.
Figure 2b shows a commercially available sampling system
based on needle valve flow controllers.
10.2.2 Prior to sample collection the sampling flow rate is
calibrated near the value used for sampling, with a
"dummy" CMS cartridge in place. Generally calibration
is accomplished using a soap bubble flow meter or
calibrated wet test meter connected to the flow exit,
assuming the entire flow system is sealed. ASTM
Method D 3686 (4) describes an appropriate calibration
scheme, not requiring a sealed flow system downstream
of the pump.
10.2.3 The flow rate should be checked before and after each
sample collection. Ideally, a rotemeter or mass flow
meter should be included in the sampling system to
allow periodic observation of the flow rate without
disrupting the sampling process.
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10.2.4 To collect an air sample the cartridges are removed
from the sealed container just prior to initiation of
the collection process.
10.2.5 The exit (unmarked) end of the cartridge is connected
to the sampling apparatus. The endcap is left on the
sample inlet and the entire system is leak checked by
activating the sampling pump and observing that no flow
is obtained over a 1 minute period. The sampling
pump is then shut off.
10.2.6 The endcap is removed from the cartridge, a particulate
filter and holder are placed on the inlet end of the
cartridge, and the sampling pump is started. In many
situations a particulate filter is not necessary since
the compounds of interest are in the vapor state. How-
ever, if, large amounts of particulate matter are
encountered, the filter may be useful to prevent con-
tamination of the cartridge. The following parameters
are recorded on an appropriate data sheet (Figure 4):
date, sampling location, time, ambient temperature,
barometric pressure, relative humidity, dry gas meter
reading (if applicable), flow rate, rotometer reading
(if applicable), cartridge number, pump, and dry gas
meter serial number.
10.2.7 The samples are collected for the desired time,
periodically recording the variables listed above. At
the end of the sampling period the parameters listed
in 10.2.6 are recorded and the flow rate is checked.
If the flows at the beginning and end of the sampling
period differ by more than 10%, the cartridge should
be marked as suspect.
10.2.8 The cartridges are removed (one at a time), the
endcaps are replaced, and the cartridges are placed
into the original container. The friction top can
is sealed and packaged for immediate shipment to the
analytical laboratory.
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10.2.9 The average sample rate is calculated and recorded
for each cartridge according to the following equation:
where
Q^ = Average flow rate in ml/minute.
Q-,, Qp,...Q., = Flow rates determined at
beginning, end, and immediate points
during sampling.
N = Number of points averaged.
10-2.10 The total volumetric flow is obtained directly from
the dry gas meter or calculated and recorded for
each cartridge using the following equation:
„ _Tx«A
where
TOOTT
V = Total volume sampled in liters at measured
temperature and pressure.
T = Sampling time = T9-T,, minutes.
10.2.11 The total volume sampled (Vg) at standard conditions,
760 mm Hg and 25°C, is calculated from the following
equation:
Pa 298
's 'm x 760 x 273 + ta
V. = V.
where
Pa = Average barometric pressure, mm Hg
ta = Average ambient temperature, °C.
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11. Sample Analysis
11.1 Sample Purging
11.1.1 Prior to analysis all samples are purged at room
temperature with pure, dry air or nitrogen to remove
water vapor. Purging is accomplished as described
in 9.7 except that the gas flow is in the same direction
as sample flow (i.e. marked end of cartridge is
connected to the flow system).
11.1.2 The sample is purged at 500 mL/minute for 5 minutes.
After purging the endcaps are immediately replaced.
The cartridges are returned to the metal can or
analyzed immediately.
11:1.3 If very humid air is being sampled the purge time
may be increased to more efficiently remove water
vapor. However, the sum of sample volume and purge
volume must be less than 75% of the retention volume for
the most volatile component of interest.
11.2 GC/MS Setup
11.2.1 Considerable variation from one laboratory to another
is expected in terms of instrument configuration.
Therefore, each laboratory must be responsible for
verifying that their particular system yields satis-
factory results. Section 14 discusses specific
performance criteria which should be met.
11.2.2 A block diagram of the analytical system required
for analysis of CMS cartridges is depicted in Figure 3.
The thermal desorption system must be designed to
accommodate the particular cartridge configuration.
For the CMS cartridge design shown in Figure 1, the
cartridge heating is accomplished as described in 9.8.
The use of a desorption oven, in conjunction with a
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simplier cartridge design is also acceptable. Exposure
of the sample to metal surfaces should be minimized and
only stainless steel or nickel should be employed.
The volume of tubing leading from the cartridge to
the GC column must be minimized and all areas must
be well-swept by helium carrier gas.
11.2.3 The GC column oven must be capable of being cooled to
-70°C and subsequently temperature programmed to 150°C.
11.2.4 The specific GC column and temperature program employed
will be dependent on the compounds of interest. Appro-
priate conditions are described in the literature (2).
In general, a nonpolar stationary phase (e.g. SE-30,
OV-1) temperature programmed from -70 to 150°C at 8°/
minute will be suitable. Fused silica, bonded-phase
columns are preferable to glass columns since they are
more rugged and can be inserted directly into the MS
ion source, thereby eliminating the need for a GC/MS
transfer line. Fused silica columns are also more
readily connected to the GC injection valve (Figure 3).
A drawback of fused silica, bonded-phase columns is the
lower capacity compared to coated, glass capillary
columns. In most cases the column capacity will be less
than 1 microgram injected for fused silica columns.
11.2.5 Capillary column dimensions of 0.3 mm ID and 50 meters
long are generally appropriate although shorter lengths
may be sufficient in many cases.
11.2.6 Prior to instrument calibration or sample analysis the
GC/MS system is assembled as shown in Figure 3. Helium
purge flow (through the cartridge) and carrier flow are
set at approximately 50 mL/minute and 2-3 mL/minute
respectively. When a cartridge is not in place a union
is placed in the helium purge line to ensure a continuous
inert gas flow through the injection loop.
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11.2.7 Once the column and other system components are assembled
and the various flows established the column temperature
is increased to 250°C for approximately four hours (or
overnight if desired) to condition the column.
11.2.8 The MS and data system are set up according to the
manufacturer's instructions. Electron impact ionization
(70eV) and an electron multiplier gain of approximately
4
5 x 10 should be employed. Once the entire GC/MS
system has been setup the system is calibrated as described
in Section 11.3. The user should prepare a detailed
standard operating procedure (SOP) describing this process
for the particular instrument being used.
11.3 GC/MS Calibration
11.3.1 Tuning and mass standardization of the MS system is per-
formed according to manufacturer's instructions
and relevant user prepared SOPs. Perfluorotributyl amine
(FC-43) should generally be employed as the reference
compound. The material is introduced directly into the
ion source through a molecular leak. The instrumental
parameters (e.g., lens voltages, resolution, etc.)
should be adjusted to give the relative ion abundances
shown in Table 2, as well as acceptable resolution and
peak shape. If these approximate relative abundances
cannot be achieved, the ion source may require cleaning
according to manufacturer's instructions. In the event
that the user's instrument cannot achieve these relative
ion abundances, but is otherwise operating properly,
the user may adopt another set of relative abundances
as performance criteria. However, these alternate
values must be repeatable on a day-to-day basis.
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11.3.2 After the mass standardization and tuning process has
been completed and the appropriate values entered into
the data system, the user should then calibrate the
entire GC/MS system by introducing known quantities
of the components of interest into the system. Three
alternate procedures may be employed for the calibra-
tion process including 1) direct injection of dilute
vapor phase standards, prepared in a dilution bottle
or compressed gas cylinder, onto the GC column,
2) injection of dilute vapor phase standards into a
flowing inert gas stream directed onto a CMS cartridge,
and 3) introduction of permeation or diffusion tube
standards onto a CMS cartridge. Direct injection of a
compressed gas cylinder (aluminum) standard containing
trace levels of the compounds of interest has been found
to be the most convenient practice since such standards
are stable over a several month period. The standards
preparation processes for the various approaches are
described in Section 13. The following paragraphs
describe the instrument calibration process for these
approaches.
11.3.3 If the system is to be calibrated by direct injection
of a vapor phase standard, the standard, in either a
compressed gas cylinder or dilution flask, is obtained
as described in Section 13. The MS and data system
are setup for acquisition, but the ionizer filament
is shut off. The GC column oven is cooled to -70°C,
the injection valve is placed in the load mode, and the
cryogenic loop is immersed in liquid nitrogen or liquid
argon. Liquid argon is required for standards prepared
in nitrogen or air, but not for standards prepared in
helium. A known volume of the standard (10-1000 ml)
is injected through the cryogenic loop at a rate of
10-100 mL/minute.
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11.3.4 Immediately after loading the vapor phase standard, the
injection valve is placed in the inject mode, the GC
program and system clock are started, and the cryogenic
loop is heated to 60°C by applying voltage (15-20 volts)
to the thermocouple wire heater surrounding the loop.
The voltage is adjusted to maintain a loop temperature
of 60°C. An automatic temperature controller can be
used in place of the manual control system. After
elution of unretained components (<3 minutes after
injection) the ionizer filament is turned on and data
acquisition is initiated. The helium purge line (set
at 50 mL/minute) is connected to the injection valve
and the valve is returned to the load mode. The loop
temperature is increased to 150°C, with helium purge,
and held at this temperature until the next sample is
to be loaded.
11.3.5 After the last component of interest has eluted,
acquisition is terminated and the data is processed as
described in Section 11.3.8. The standard injection
process is repeated using different standard concentra-
tions and/or volumes to cover the analytical range of
interest.
11.3.6 If the system is to be calibrated by analysis of
standard CMS cartridges, a series of cartridges is
prepared as described in Sections 13.2 or 13.3. Prior
to analysis the cartridges are stored (no longer than
48 hours) as described in Section 9.10. For analysis
the injection valve is placed in the load mode and the
cryogenic loop is immersed in liquid nitrogen (or
liquid argon if desired). The CMS cartridge is installed
in the helium purge line (set at 50 mL/minute) so that
the helium flow through the cartridge is opposite to
the direction of sample flow and the purge gas is
directed through the cryogenic loop and vented to the
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atmosphere. The CMS cartridge is heated to 370-400°C
and maintained at this temperature for 10 minutes (using
the temperature control process described in Section 9.8).
During the desorption period, the GC column oven is
cooled to -70°C and the MS and data system are setup for
acquisition, but the ionizer filament is turned off.
11.3.7 At the end of the 10 minute desorption period, the ana-
lytical process described in Sections 11.3.4 and 11.3.5
is conducted. During the GC/MS analysis heating of the
CMS cartridge is discontinued. Helium flow is maintained
through the CMS cartridge and cryogenic loop until the
cartridge has cooled to room temperature. At that time,
the cryogenic loop is allowed to cool to room temperature
and the system is ready for further cartridge analysis.
Helium flow is maintained through the cryogenic loop at
all times, except during the installation or removal of
a CMS cartridge, to minimize contamination of the loop.
11.3.8 Data processing for instrument calibration involves
determining retention times, and integrated characteristic
ion intensities for each of the compounds of interest.
In addition, for at least one chromatographic run, the
individual mass spectra should be inspected and compared
to reference spectra to ensure proper instrumental
performance. Since the steps involved in data processing
are highly instrument specific,.the user should prepare
a SOP describing the process for individual use. Overall
performance criteria for instrument calibration are
provided in Section 14. If these criteria are not
achieved, the user should refine the instrumental
parameters and/or operating procedures to meet these
criteria.
11.4 Sample Analysis
11.4.1 The sample analysis is identical to that described
in Sections 11.3.6 and 11.3.7 for the analysis of
standard CMS cartridges.
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11.4.2 Data processing for sample data generally involves
1) qualitatively determining the presence or absence
of each component of interest on the basis of a set
of characteristic ions and the retention time using
a reversed-search software routine, 2) quantification
of each identified component by integrating the intensity
of a characteristic ion and comparing the value to
that of the calibration standard, and 3) tentative
identification of other components observed using a
forward (library) search software routine. As for
other user specific processes, a SOP should be prepared
describing the specific operations for each individual
laboratory.
12. Calculations
12.1 Calibration Response Factors
12.1.1 Data from calibration standards is used to calculate a
response factor for each component of interest.
Ideally the process involves analysis of at least three
calibration levels of each component during a given
day and determination of the response factor (area/
nanogram injected) from the linear least squares
fit of a plot of nanograms injected versus area
(for the characteristic ion). In general, quantities
of components greater than 1,000 nanograms should not
be injected because of column overloading and/or MS
response nonlinearity.
12.1.2 In practice the daily routine may not always allow
analysis of three such calibration standards. In
this situation calibration data from consecutive days
may be pooled to yield a response factor, provided
that analysis of replicate standards of the same
concentration are shown to agree within 20% on the
consecutive days. In all cases one given standard
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concentration, near the midpoint of the analytical
range of interest, should be injected at least once
each day to determine day-to-day precision of response
factors.
12.1.3 Since substantial nonlinearity may be present in the
calibration curve, a nonlinear least squares fit
(e.g. quadratic) should be employed. This process
involves fitting the data to the following equation:
Y = A + BX + CX2
where
Y = peak area
X = quantity of component injected nanograms
A, B, and C are coefficients in the equation.
12.2 Analyte Concentrations
12.2.1 Analyte quantities on a sample cartridge are calculated
from the following equation:
YA = A + BXA + CX2
where Y. is the area of the analyte characteristic ion for
the sample cartridge.
X/\ is the calculated quantity of analyte on the sample
cartridge, in nanograms.
A, B, and C are the coefficients calculated from the
calibration curve described in Section 12.1.3.
12.2.2 If instrumental response is essentially linear over the
concentration range of interest, a linear equation
(C=0 in the equation above) can be employed.
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12.2.3 Concentration of analyte in the original air sample
is calculated from the following equation:
C =XA
CA
where
C. is the calculated concentration of analyte in ng/L.
Vs and X. are as previously defined in Section 10.2.11
and 12.2.1, respectively.
13. Standard Preparation
13.1 Standards for Direct Injection
13.1.1 Standards for direct injection can be prepared in
compressed gas cylinders or in dilution vessels.
The dilution flask protocol has been described in
detail in another method and is not repeated here (6).
For the CMS method where only volatile compounds
(boiling point <120°C) are of concern, the preparation
of dilute standards in 15 liter aluminum compressed
gas cylinders has been found to be most convenient.
These standards are generally stable over at least a
3-4 month period and in some cases can be purchased
from commercial suppliers on a custom prepared basis.
13.1.2 Preparation of compressed gas cylinders requires
working with high pressure tubing and fittings, thus
requiring a user prepared SOP which ensures that
adequate safety precautions are taken. Basically,
the preparation process involves injecting a pre-
determined amount of neat liquid or gas into an
empty high pressure cylinder of known volume, using
gas flow into the cylinder to complete the transfer.
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The cylinder is then pressurized to a given value
(500-1000 psi). The final cylinder pressure must be
determined using a high precision gauge after the
cylinder has thermally equilibrated for a 1-2 hour
period after filling.
13.1.2 The concentration of components in the cylinder
standard should be determined by comparison with
National Bureau of Standards reference standards
(e.g. SRM 1805-benzene in nitrogen) when available.
13.1.3 The theoretical concentration (at 25°C and 760 mm
pressure) for preparation of cylinder standards
can be calculated using the following equation:
CT = VI x d 14.7 x 24.4 x 1000
Vc x Pc + 14>7
where CT is the component concentration, in ng/mL at 25°C
and 760 mm Hg pressure.
Vj is the volume of neat liquid component injected,
in yL.
Vc is the internal volume of the cylinder, in L.
d is the density of the neat liquid component,
in g/mL.
PC is the final pressure of the cylinder standards,
in pounds per square inch gauge (psig).
13.2 Preparation of Spiked Traps by Vapor Phase Injection
This process involves preparation of a dilution flask
or compressed gas cylinder containing the desired concentra-
tions of the compound(s) of interest and injecting the desired
volume of vapor into a flowing gas stream which is directed
onto a clean CMS cartridge. The procedure is described in
detail in another method within the Compendium (6) and will not be
repeated here.
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13.3 Preparation of Spiked Traps Using Permeation or Diffusion Tubes
13.3.1 A flowing stream of inert gas containing known amounts
of each compound of interest is generated according
to ASTM Method D3609 (4). Note that a method of
accurately maintaining temperature within +_ 0.1°C is
required and the system generally must be equilibrated
for at least 48 hours before use.
13.3.2 An accurately known volume of the standard gas stream
(usually 0.1-1 liter) is drawn through a clean CMS
cartridge using the sampling system described in
Section 10.2.1, or a similar system. However, if mass
flow controllers are employed, they must be calibrated
for the carrier gas used in Section 13.3.1 (usually
nitrogen). Use of air as the carrier gas for permeation
systems is not recommended, unless the compounds of
interest are known to be highly stable in air.
13.3.3 The spiked traps are then stored or immediately
analyzed as in Sections 11.3.6 and 11.3.7.
14. Performance Criteria and Quality Assurance
This section summarizes the quality assurance (QA) measures and
provides guidance concerning performance criteria which should be
achieved within each laboratory. In many cases the specific QA
procedures have been described within the appropriate section
describing the particular activity (e.g. parallel sampling).
14.1 Standard Operating Procedures (SOPs)
14.1.1 Each user should generate SOPs describing the following
activities as accomplished in their laboratory:
1) assembly, calibration and operation of the sampling
system, 2) preparation, handling and storage of CMS
cartridges, 3) assembly and operation of GC/MS system
including the thermal desorption apparatus and data
system, and 4) all aspects of data recording and processing
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14.1.2 SOPs should provide specific stepwise instructions and
should be readily available to, and understood by the
laboratory personnel conducting the work.
14.2 CMS Cartridge Preparation
14.2.1 Each batch of CMS cartridges, prepared as described in
Section 9, should be checked for contamination by
analyzing one cartridge, immediately after preparation.
While analysis can be accomplished by GC/MS, many
laboratories may chose to use GC/FID due to logistical
and cost considerations.
14.2.2 Analysis by GC/FID is accomplished as described for
GC/MS (Section 11) except for use of FID detection.
14.2.3 While acceptance criteria can vary depending on the
components of interest, at a minimum the clean
cartridge should be demonstrated to contain less than
one-fourth of the minimum level of interest for each
component. For most compounds the blank level should
be less than 10 nanograms per cartridge in order to be
acceptable. More rigid criteria may be adopted, if
necessary, within a specific laboratory. If a cartridge
does not meet these acceptance criteria, the entire lot
should be rejected.
14.3 Sample Collection
14.3.1 During each sampling event at least one clean cartridge
will accompany the samples to the field and back to the
laboratory, having been placed in the sampler but without
sampling air, to serve as a field blank. The average
amount of material found on the field blank cartridges
may be subtracted from the amount found on the actual
samples. However, if the blank level is greater than
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25% of the sample amount, data for that component
must be identified as suspect.
14.3.2 During each sampling event at least one set of
parallel samples (two or more samples collected
simultaneously) should be collected, preferably at
different flow rates as described in Section 10.1.4.
If agreement between parallel samples is not generally
within +25% the user should collect parallel samples
on a much more frequent basis (perhaps for all sampling
points). If a trend of lower apparent concentrations
with increasing flow rate is observed for a set of
parallel samples one should consider usi/ig a reduced
sampling rate and longer sampling interval, if possible.
If this practice does not improve the reproducibility
further evaluation of the method performance for the
compound of interest might be required.
14.3.3 Backup cartridges (two cartridges in series) should be
collected with each sampling event. Backup cartridges
should contain less than 10% of the amount of components
of interest found in the front cartridges, or be equiva-
lent to the blank cartridge level, whichever is greater.
14.4 GC/MS Analysis
14.4.1 Performance criteria for MS tuning and mass standardiza-
tion have been discussed in Section 11.2 and Table 2.
Additional criteria can be used by the laboratory,
if desired. The following sections provide performance
guidance and suggested criteria for determining the
acceptability of the GC/MS system.
-------
T02-25
14.4.2 Chromatographic efficiency should be evaluated daily
by the injection of calibration standards. A reference
compound(s) should be chosen from the calibration
standard and plotted on an expanded time scale so that
its width at 10% of the peak height can be calculated,
as shown in Figure 6. The width of the peak at 10%
height should not exceed 10 seconds. More stringent
criteria may be required for certain applications.
The asymmetry factor (see Figure 6) should be between
0.8 and 2.0. The user should also evaluate chroma-
tographic performance for any polar or reactive compounds
of interest, using the process described above. If peaks
are observed that exceed the peak width or asymmetry
factor criteria above, one should inspect the entire
system to determine if unswept zones or cold spots are
present in any of the fittings or tubing and/or if
replacement of the GC column is required. Some labora-
tories may chose to evaluate column performance separately
by direct injection of a test mixture onto the GC
column. Suitable schemes for column evaluation have been
reported in the literature (7).
14.4.3 The detection limit for each component is calculated
from the data obtained for calibration standards. The
detection limit is defined as
DL = A + 3.3S
where
DL is the calculated detection limit in nanograms
injected.
A is the intercept calculated in Section 12.1.3.
S is the standard deviation of replicate determina-
tions of the lowest level standard (at least three
such determinations are required). The lowest
-------
T02-26
level standard should yield a signal to noise ratio
(from the total ion current response) of approximately 5.
14.4.4 The relative standard deviation for replicate analyses
of cartridges spiked at approximately 10 times the
detection limit should be 20% or less. Day to day
relative standard deviation for replicate cartridges
should be 25% or less.
14.4.5 A useful performance evaluation step is the use of an
internal standard to track system performance. This
is accomplished by spiking each cartridge, including
blank, sample, and calibration cartridges with approx-
imately 100 nanograms of a compound not generally
present is ambient air (e.g. perfluorotoluene). Spik-
ing is readily accomplished using the procedure outlined
in Section 13.2, using a compressed gas standard. The
integrated ion intensity for this compound helps to
identify problems with a specific sample. In general
the user should calculate the standard deviation of the
internal standard response for a given set of samples
analyzed under identical tuning and calibration conditions,
Any sample giving a value greater than +_ 2 standard
deviations from the mean (calculated excluding that
particular sample) should be identified as suspect.
Any marked change in internal standard response may
indicate a need for instrument recalibration.
14.5 Method Precision and Recovery
14.5.1 Recovery and precision data for selected volatile organic
compounds are presented in Table 1. These data were
obtained using ambient air, spiked with known amounts
of the compounds in a dynamic mixing system (2).
14.5.2 The data in Table 1 indicate that in general recoveries
better than 75% and precision (relative standard
deviations) of 15-20% can be obtained. However,
selected compounds (e.g. carbon tetrachloride and
-------
T02-27
benzene) will have poorer precision and/or recovery.
The user must check recovery and precision for any
compounds for which quantitative data are needed.
-------
T02-28
References
1. Kebbekus, B. B. and J. W. Bozzelli. Collection and Analysis of
Selected Volatile Organic Compounds in Ambient Air. Proceedings
of Air Pollution Control Association, Paper No. 82-65.2, Air
Pollution Control Association, Pittsburgh, Pennsylvania, 1982.
2. Riggin R. M. and L. E. Slivon. Determination of Volatile Organic
Compounds in Ambient Air Using Carbon Molecular Sieve Adsorbants,
Special Report on Contract 68-02-3745 (WA-7), U.S. Environmental
Protection Agency, Research Triangle Park, North Carolina, September,
1983.
3. Riggin, R. M., "Technical Assistance Document for Sampling and
Analysis of Toxic Organic Compounds in Ambient Air", EPA-600/4-
83-027, U.S. Environmental Protection Agency, Research Triangle
Park, North Carolina, 1983.
4. Annual Book of ASTM Standards, Part 11.03, "Atmospheric Analysis:
Occupational Health and Safety", American Society for Testing and
Materials, 1983.
5. Walling, J. F., Berkley, R. E., Swanson, D. H., and Toth, F. J.
"Sampling Air for Gaseous Organic Chemical-Applications to Tenax",
EPA-600/7-54-82-059, U.S. Environmental Protection Agency, Research
Triangle Park, North Carolina, 1982.
6. This Methods Compendium - Tenax Method (TO 1).
7. Grob, K., Jr., Grob, G., and Grob, K., "Comprehensive Standardized
Quality Test for Glass Capillary Columns", J. Chromatog., 156
1-20, 1978.
-------
TABLE 1. VOLATILE ORGANIC COMPOUNDS FOR WHICH THE
CMS ADSORPTION METHOD HAS BEEN EVALUATED
Compound
Vinyl Chloride
Acrylonitrile
Vinylidene Chloride
Methylene Chloride
Ally! Chloride
Chloroform
1 ,2-Dichloroethane
1 ,1 ,1-Trichloroethane
Benzene
Carbon Tetrachloride
Tol uene
Retention
Time,/ x
6.3
10.8
10.9
11.3
11.4
13.8
14.5
14.7
15.4
15.5
18.0
Characteristic
Mass Fragment
Used For
Quantification
62
53
96
84
76
83
62
97
78
117
91
Method Performance -Data^ '
Concentration,
ng/L
17
20
36
28
32
89
37
100
15
86
4.1
Percent
Recovery
74
85
94
93
72
91
85
75
140
55
98
Standard
Deviation
19
18
19
16
19
12
11
9.1
37
2.9
5.4
a) GC conditions as follows:
Column - Hewlett Packard, crosslinked methyl silicone,
0.32 mm ID x 50 mm long, thick film, fused silica.
Temperature Program - 70°C for 2 minutes then increased at
8°C/minute to 120°C.
b) From Reference 2. For spiked ambient air.
o
ro
ro
-------
T02-30
TABLE 2. SUGGESTED PERFORMANCE CRITERIA FOR RELATIVE
ION ABUNDANCES FROM FC-43 MASS CALIBRATION
M/E
51
69
100
119
131
169
219
264
314
% Relative
Abundance
1.8 +0.5
100
12.0 + 1.5
12.0 + 1.5
35.0 + 3.5
3.0 + 0.4
24.0 + 2.5
3.7 + 0.4
0.25 + 0.1
-------
T02-31
Thormocoupte
Zetex
Insulation
/- Fiberglass
/ Tape
nnnun
1/4" Nut
Thermocouple
Connector
Heater
Connector
Reducing
Union
• Stainless
Steel Tube
1/4" O.D. x 3" Long
FIGURE 1. DIAGRAM SHOWING CARBON MOLECULAR SIEVE TRAP (CMS) CONSTRUCTION
-------
T02-32
Coupling*
to Connect
CMS
Cartridges
Vent
Man Flow
Controllers
(a) Mass Flow Control
Rotomttar
Vent
Dry
Test
Meter
^m
mm
rfri
1 — V
Needle
Valve
Pump
1 Connect CMS
(b) Needle Valve Control
FIGURE 2. TYPICAL SAMPLING SYSTEM CONFIGURATIONS
-------
T02-33
Couplings for
CMS Cartridge
Vent
Heated 6-Port
Injection Valve
. • Cryogenic Loop (•*• Figure S)
Helium Twik
and Regulator
Flow
Control!*™'
Liquid Nitrogen '
HwHifn Purge
From Cooling H
OC Column
Own
GC Column
Cooling to -70 C
(b) Vaivt-Load Mod*
V*m
OC Column
(«) Vilve- Intact Mod*
Spectrometer
Cryogenic Trap
Held at Liquid N2
Temperature
Helium Carrier
Flow — 2-3 ml/minut*
Cryogenic Trap
HaMateoC
FIGURE 3. GC/MS ANALYSIS SYSTEM FOR CMS CARTRIDGES
-------
T02-3**
SAMPLING DATA SHEET
(One Sample Per Data Sheet)
PROJECT:_
SITE:
DATE(S) SAMPLED:
LOCATION:
TIME PERIOD SAMPLED:
OPERATOR:
INSTRUMENT MODEL NO:.
PUMP SERIAL NO:
SAMPLING DATA
CALIBRATED BY:
Sample Number:_
Start Time:
Stop Time:
Time
1.
2.
3.
4.
N.
Dry Gas
Meter
Reading
Rotameter
Reading
Flow
Rate,*Q
ml/Min
Ambient
Temperature
°C
Barometric
Pressure,
mmHg
Relative
Humidity, %
Comments
Total Volume Data**
Vm = (Final - Initial) Dry Gas Meter Reading, or
+ 0.2 + 0.3...QN
1
1000 x (Sampling Time in Minutes)
Liters
Liters
* Flowrate from rotameter or soap bubble calibrator
(specify which).
** Use data from dry gas meter if available.
FIGURE 4. EXAMPLE SAMPLING DATA SHEET
-------
T02-35
oc
Oo
oo
DO
OCj
1/8" to 1/16" Reducing Union
1/8" Swageiok Nut and Ferrule
Silanized
Glass
Wool
1/2" Long
60/80 Mesh Silanized Glass Beads.
Stainless Steel
Tubing
1/8" O.D. x 0.08" I.D. x 8" Long
oo
30
OC
JDC
30
OO
>o
°0
00
FIGURE 5. CRYOGENIC TRAP DESIGN
-------
T02-36
BC
Asymmetry Factor • -?-=•
AB
Example Calculation:
Paak Height - DE - 100 mm
10% Peak Height - BD • 10 mm
Peak Width at 10% Peak Height - AC - 23 mm
AB - 11 mm
BC *12mm
Therefore: Asymmetry Factor - —
1.1
FIGURE 6. PEAK ASYMMETRY CALCULATION
-------
METHOD T03 Revision 1.0
April, 1984
METHOD FOR THE DETERMINATION OF VOLATILE ORGANIC COMPOUNDS
IN AMBIENT AIR USING CRYOGENIC PRECONCENTRATION TECHNIQUES
AND GAS CHROMATOGRAPHY WITH FLAME IONIZATION AND
AND ELECTRON CAPTURE DETECTION
1. Scope
1.1 This document describes a method for the determination of
highly volatile compounds having boiling points in the range
of -10 to 200°C.
1.2 The methodology detailed in this document is currently
employed by numerous laboratories (l-4;8-ll). Modifications
to this methodology should be accompanied by appropriate
documentation of the validity and reliability of these
changes.
2. Applicable Documents
2.1 ASTM Standards
D1356 Definition of Terms Related to Atmospheric Sampling
and Analysis
E 355 Recommended Practice for Gas Chromatography Terms
and Relationships
2.2 Other Documents
Ambient Air Studies (1-4).
U. S. EPA Technical Assistance Document (5).
3. Summary of Method
3.1 Ambient air analyses are performed as follows. A collection
trap, as illustrated in Figure 1, is submerged in either
liquid oxygen or argon. Liquid argon is highly recommended
for use because of the safety hazard associated with liquid
-------
T03-2
oxygen. With the sampling valve in the fill position an
air sample is then admitted into the trap by a volume
measuring apparatus. In the meantime, the column oven is
cooled to a sub-ambient temperature (-50°C). Once sample
collection is completed, the valve is switched so that the
carrier gas sweeps the contents of the trap onto the head of
the cooled GC column. Simultaneously, the liquid cryogen is
removed and the trap is heated to assist the sample transfer
process. The GC column is temperature programmed and the
component peaks eluting from the columns are identified and
quantified using flame ionization and/or electron capture
detection. Alternate detectors (e.g. photoionization) can be
used as appropriate. An automated system incorporating
these various operations as well as the data processing
function has been described in the literature (8,9).
3.2 Due to the complexity of ambient air samples, high resolution
(capillary column) GC techniques are recommended. However,
when highly selective detectors (such as the electron
capture detector) are employed, packed column technology
without cryogenic temperature programming can be effectively
utilized in some cases.
4. Significance
4.1 Volatile organic compounds are emitted into the atmosphere
from a variety of sources including industrial and commercial
facilities, hazardous waste storage facilities, etc. Many
of these compounds are toxic, hence knowledge of the levels
of such materials in the ambient atmosphere is required in
order to determine human health impacts.
4.2 Because these organic species are present at ppb levels or
below, some means of sample preconcentration is necessary in
order to acquire sufficient material for identification and
quantitation. The two primary preconcentration techniques
are cryogenic collection and the use of solid adsorbents.
The method described herein involves the former technique.
-------
T03-3
5. Definitions
Definitions used in this document and any user prepared SOPs should
be consistent with ASTM Dl356 (6). All abbreviations and symbols
are defined within this document at the point of use.
6. Interferences/Limitations
6.1 Compounds having similar GC retention times will interfere
in the method. Replacing the flame ionization detector
with more selective detection systems will help to minimize
these interferences. Chlorinated species, in particular,
should be determined using the electron capture detector
to avoid interference from volatile hydrocarbons.
6.2 An important limitation of the technique is the condensation
of moisture in the collection trap. The possibility of
ice plugging the trap and stopping the flow is of concern,
and water subsequently transferred to the capillary column
may also result in flow stoppage and cause deleterious effects
to certain column materials. Use of permaselective Nafion®
tubing in-line before the cryogenic trap avoids this problem;
however, the material must be used with caution because of
possible loses of certain compounds. Another potential
problem is contamination from the Nafion ® tubing. The
user should consult the literature (7-12) for details on the
use of permeation-type driers.
7. Apparatus
7.1 Gas chromatograph/Flame lonization/Electron Capture
Detection System- must be capable of subambient temperature
programming. A recent publication (8) describes an automated
GC system in which the cyrogenic sampling and analysis
features are combined. This system allows simultaneous
flame ionization and electron capture detection.
-------
T03-4
7.2 Six-port sampling valve - modified to accept a sample
collection trap (Figure 1).
7.3 Collection trap - 20 cm x 0.2 cm I.D. stainless steel
tubing packed with 60/80 mesh silanized glass beads and sealed
with glass wool. For the manual system (Section 9.2) the
trap is externally wrapped with 28 gauge (duplex and
fiberglass insulated) type "K" thermocouple wire. This
wire, beaded at one end, is connected to a powerstat
during the heating cycle. A thermocouple is also attached
to the trap as shown in Figure 1.
7.4 Powerstat - for heating trap.
7.5 Temperature readout device - for measuring trap temperature
during heating cycle.
7.6 Glass dewar flask - for holding cryogen.
7.7 Sample volume measuring apparatus - capable of accurately
and precisely measuring a total sample volume up to 500 cc
at sampling rates between 10 and 200 cc/minute. See Section 9.
7.8 Stopwatch.
7.9 Dilution container for standards preparation - glass flasks
or Teflon (Tedlar) bags, .002 inch film thickness (see
Figure 2).
7.10 Liquid microliter syringes - 5-50 yl for injecting liquid
standards into dilution container.
7.11 Volumetric flasks - various sizes, 1-10 ml.
7.12 GC column - Hewlett Packard 50 meter methyl silicone cross-
linked fused silica column (.3 mm I.D., thick film) or
equivalent.
7.13 Mass flow controller - 10-200 mL/minute flow control range.
7.14 Permeation drier - PermaPure® - Model MD-125F, or equivalent.
Alternate designs described in the literature (7-12) may also
be acceptable.
8. Reagents and Materials
8.1 Glass beads - 60/80 mesh, silanized.
-------
T03-5
8.2 Glasswool - silanized.
8.3 Helium - zero grade compressed gas, 99.9999%.
8.4 Hydrogen - zero grade compressed gas, 99.9999%.
8.5 Air - zero grade compressed gas.
8.6 Liquid argon (or liquid oxygen).
8.7 Liquid nitrogen.
8.8 SRM 1805 - benzene in nitrogen standard. Available from the
National Bureau of Standards. Additional such standards will
become available in the future.
8.9 Chemical standards - neat compounds of interest, highest
purity available.
9. Sampling and Analysis Apparatus
Two systems are described below which allow collection of an
accurately known volume of air (100-1000 ml) onto a cryogenically
cooled trap. The first system (Section 9.1) is an automated
device described in the literature (8,9). The second system
(Section 9.2) is a manual device, also described in the liter-
ature (2).
9.1 The automated sampling and analysis system is shown in Figure
3. This system is composed of an automated GC system
(Hewlett Packard Model 5880A, Level 4, or equivalent) and a
sample collection system (Nutech Model 320-01, or equivalent).
The overall system is described in the literature (8).
9.1.1 The electronic console of the sampling unit controls
the mechanical operation of the six-port valve and
cryogenic trapping components as well as the tempera-
tures in each of the three zones (sample trap, transfer
line, and valve).
-------
T03-6
9.1,2 The valve (six-port air activated, Seiscor Model 8
or equivalent) and transfer line are constantly
maintained at 120°C. During sample collection the
trap temperature is maintained at -160 + 5°C by
a flow of liquid nitrogen controlled by a solenoid
valve. A cylindrical 250 with heater, held in
direct contact with the trap, is used to heat the
trap to 120°C in 60 seconds or less during the sample
desorption step. The construction of the sample
trap is described in Section 7.3.
9.1.3 The sample flow is controlled by a pump/mass flow
controller assembly, as shown in Figure 3. A sample
flow of 10-100 mL/minute is generally employed,
depending on the desired sampling period. A total
volume of 100-1000 ml is commonly collected.
9.1.4 In many situations a permaselective drier (e.g.
Nafion®) may be required to remove moisture from
the sample. Such a device is installed at the sample
inlet. Two configurations for such devices are
available. The first configuration is the tube and
shell type in which the sample flow tube is surrounded
by an outer shell through which a countercurrent flow
of clean, dry air is maintained. The dry air stream
must be free from contaminants and its flow rate should
be 3-4 times greater than the sample flow to achieve
effective drying. A second configuration (7)
involves placing a drying agent, e.g. magnesium
carbonate, on the outside of the sample flow tube.
This approach eliminates the need for a source
of clean air in the field. However, contamination
from the drying agent can be a problem.
9.2 The manual sampling consists of the sample volume measuring
apparatus shown in Figure 4 connected to the cryogenic trap/
GC assembly shown in Figure 1. The operation of this
-------
T03-7
assembly is described below.
9.2.1 Pump-Down Position
The purpose of the pump-down mode of operation is to
evacuate the ballast tank in preparation for col-
lecting a sample as illustrated in Figure 4. (While in
this position, helium can also be utilized to back-
flush the sample line, trap, etc. However, this
cleaning procedure is not normally needed during most
sampling operations). The pump used for evacuating
the system should be capable of attaining 200 torr
pressure.
9.2.2 Volume Measuring Position
Once the system has been sufficiently evacuated,
the 4-way ball valve is switched to prepare for sample
collection. The 3-position valve is used to initiate
sample flow while the needle valve controls the rate
of flow.
9.2.3 Sample Volume Calculation
The volume of air that has passed through the col-
lection trap corresponds to a known change in pressure
within the ballast tank (as measured by the Wallace
Tiernan gauge). Knowing the volume, pressure change,
and temperature of the system, the ideal gas law can
be used to calculate the number of moles of air
sampled. On a volume basis, this converts to the
following equation:
_ AP 298
760 TA+ 273
-------
T03-8
where
Vs = Volume sampled at 760 mm Hg pressure and
25°C.
AP = Change in pressure within the ballast tank,
mm of Hg.
V = Volume of ballast tank and gauge.
TA = Temperature of ballast tank, °C.
The internal volume of the ballast tank and gauge
can be determined either by H20 displacement or by
injecting calibrated volumes of air into the system
using large volume syringes, etc.
10. Sampling and Analysis Procedure - Manual Device
10.1 This procedure assumes the use of the manual sampling system
described in Section 9.2
10.2 Prior to sample collection, the entire assembly should
be leak-checked. This task is accomplished by sealing
the sampling inlet line, pumping the unit down and placing
the unit in the flow measuring mode of operation. An initial
reading on the absolute pressure gauge is taken and rechecked
after 10 minutes. No apparent change should be detected.
10.3 Preparation for sample collection is carried out by switching
the 6-port valve to the "fill" position and connecting the
heated sample line to the sample source. Meanwhile the
collection trap is heated to 150°C (or other appropriate
temperature). The volume measuring apparatus is pumped-down
and switched to the flow measuring mode. The 3-position
valve is opened and a known volume of sample is then passed
through the heated sample line.and trap to purge the
system.
-------
TO 3-9
10.4 After the system purge is completed, the 3-position valve is
closed and the corresponding gauge pressure is recorded.
The collection trap is then immersed into a dewar of liquid
argon (or liquid oxygen) and the 3-position valve is
temporarily opened to draw in a known volume of air, i.e.
a change in pressure corresponds to a specific volume of
air (see Section 9). Liquid nitrogen cannot be used as the
cryogen since it will also condense oxygen from the air.
Liquid oxygen represents a potential fire hazard and should
not be employed unless absolutely necessary.
10.5 After sample collection is completed, the 6-port valve is
switched to the inject position, the dewar is removed and
the trap is heated to 150°C to transfer the sample components
to the head of the GC column which is initially maintained
at -50°C. Temperature programming is initiated to elute
the compounds of interest.
10.6 A GC integrator (or data system if available) is activated
during the injection cycle to provide component identification
and quantisation.
11. Sampling and Analysis Procedure - Automated Device
11.1 This procedure assumes the use of the automated system shown
in Figure 3. The components of this system are discussed
in Section 9.1.
11.2 Prior to initial sample collection the entire assembly should
be leak-checked. This task is completed by sealing the
sample inlet line and noting that the flow indication or the
mass flow controller drops to zero (less than 1 mL/minute).
11.3 The sample trap, valve, and transfer line are heated to
120°C and ambient air is drawn through the apparatus
(M50 mL/minute) for a period of time 5-10 minutes to flush
the system, with the sample valve in the inject position.
During this time the GC column is maintained at 150°C to
condition the column.
-------
T03-10
11.4 The sample trap is then cooled to -160 + 5°C using a
controlled flow of liquid nitrogen. Once the trap
temperature has stabilized,sample flow through the
trap is initiated by placing the valve in the inject
position and the desired volume of air is collected.
11.5 During the sample collection period the GC column is
stabilized at -50°C to allow for immediate injection
of the sample after collection.
11.6 At the end of the collection period the valve is
immediately placed in the inject position, and the
cryogenic trap is rapidly heated to 120°C to desorb
the components onto GC column. The GC temperature
program and data acquisition are initiated at this
time.
11.7 At the desired time the cryogenic trap is cooled to - 160°C,
the valve is returned to the collect position and the next
sample collection is initiated (to coincide with the completion
of the GC analysis of the previous sample).
12. Calibration Procedure
Prior to sample analysis, and approximately every 4-6 hours there-
after, a calibration standard must be analyzed, using the identical
procedure employed for ambient air samples (either Section 10 or 11).
This section describes three alternative approaches for preparing
suitable standards.
12.1 Teflon® (on Tedlar®) Bags
12.1.1 The bag (nominal size; 20L) is filled with zero air
and leaked checked. This can be easily accomplished
by placing a moderate weight (text book) on the
inflated bag and leaving overnight. No visible change
in bag volume indicates a good seal. The bag should
also be equipped with a quick-connect fitting for
sample withdrawal and an insertion port for liquid
injections (Figure 2).
-------
T03-11
12.1.2 Before preparing a standard mixture, the bag is
sequentially filled and evacuated with zero air
(5 times). After the 5th filling, a sample blank
is obtained using the sampling procedure outlined
in Section 10.
12.1.3 In order to prepare a standard mixture, the bag is
filled with a known volume of zero air. This flow
should be measured via a calibrated mass flow
controller or equivalent flow measuring device.
A measured aliquot of each analyte of interest is
injected into the bag through the insertion port
using a microliter syringe. For those compounds
with vapor pressures lower than benzene or for strongly
adsorbed species, the bag should be heated
(60°C) oven) during the entire calibration period.
12.1.4 To withdraw a sample for analysis, the sampling line
is directly connected to the bag. Quick connect
fittings allow this hook-up to be easily accomplished
and also minimizes bag contamination from labora-
tory air. Sample collection is initiated as described
earlier.
12.2 Glass Flasks
12.2.1 If a glass flask is employed (Figure 2) the exact
volume is determined by weighing the flask before
and after filling with deionized water. The flask
is dried by heating at 200°C.
12.2.2 To prepare a standard, the dried flask is flushed with
zero air until cleaned (i.e. a blank run is made).
An appropriate aliquot of each analyte is injected
using the same procedures as described for preparing
bag standards.
12.2.3 To withdraw a standard for analysis, the GC
sampling line is directly connected to the flask
and a sample obtained. However, because the flask
-------
T03-12
is a rigid container, it will not remain at
atmospheric pressure after sampling has commenced.
In order to prevent room air leakage into the flask,
it is recommended that no more than 10% of the initial
volume be exhausted during the calibration period
(i.e. 200 cc if a 2 liter flask is used).
12.3 Pressurized Gas Cylinders
12.3.1 Pressurized gas cylinders containing selected analytes
at ppb concentrations in air can be prepared or
purchased. A limited number of analytes (e.g.
benzene, propane) are available from NBS.
12.3.2 Speciality gas suppliers will prepare custom gas
mixtures, and will cross reference the analyte
concentrations to an NBS standard for an additional
charge. In general, the user should purchase such
custom mixtures, rather than attempting to prepare
them because of the special high pressure filling
apparatus required. However, the concentrations should
be checked, either by the supplier or the user using
NBS reference materials.
12.3.3 Generally, aluminum cylinders are suitable since most
analytes of potential interest in this method have
been shown to be stable for at least several months
in such cylinders. Regulators constructed of stainless
steel and Teflon® (no silicon or neoprene rubber).
12.3.4 Before use the tank regulator should be flushed by
alternately pressuring with the tank mixture, closing
the tank valve, and venting the regulator contents to
the atmosphere several times.
12.3.5 For calibration a continuous flow of the gas mixture
should be maintained through a glass or Teflon® manifold
from which the calibration standard is drawn. To
generate various calibration concentrations the
-------
T03-13
pressurized gas mixture can be diluted, as desired,
with zero grade air using a dynamic dilution system
(e.g. CSI Model 1700 ).
13. Calibration Strategy
13.1 Vapor phase standards can be prepared with either neat
liquids or diluted liquid mixtures depending upon the
concentration levels desired. It is recommended that benzene,
also be included in this preparation scheme so that flame
ionization detector response factors, relative to benzene,
can be determined for the other compounds. The benzene
concentration generated in this fashion should be cross-
checked with an NBS (e.g. SRM 1805) for accuracy determina-
tions.
13.2 Under normal conditions, weekly multipoint calibrations
should be conducted. Each multipoint calibration should
include a blank run and four concentration levels for the
target species. The generated concentrations should bracket
the expected concentration of ambient air samples.
13.3 A plot of nanograms injected versus area using a linear
least squares fit of the calibration data will yield the
following equation:
Y = A + BX
where
Y = quantity of component, nanograms
A = intercept
B = slope (response factor)
If substantial nonlinearity is present in the calibration
curve a quadratic fit of the data can be used:
-------
T03-14
Y = A + BX + CX2
where
C = constant
Alternatively, a, stepwise multilevel calibration scheme
may be used if more convenient for the data system in use.
14. Performance Criteria and Quality Assurance
This section summarizes the quality assurance (QA) measures and
provides guidance concerning performance criteria which should be
achieved within each laboratory.
14.1 Standard Operating Procedures (SOPs)
14.1.1 Each user should generate SOPs describing the
following activities as accomplished in their
laboratories:
1) assembly, calibration and operation of
the sampling system.
2) preparation and handling of calibration
standards.
3) assembly, calibration and operation of the
GC/FID system and
4) all aspects of data recording and processing.
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T03-15
14.1.2 SOPs should provide specific stepwise instructions
and should be readily available to, and understood
by, the laboratory personnel conducting the work.
14.2 Method Sensitivity, Precision and Accuracy
14.2.1 System sensitivity (detection limit) for each
component is calculated from the data obtained for
calibration standards. The detection limit is
defined as
DL = A + 3.3S
where
DL = calculated detection limit in
nanograms injected.
A = intercept calculated in Section 13.
S = standard deviation of replicate
determination of the lowest level
standard (at least three deter-
minations are required).
For many compounds detection limits of 1 to 5
nanograms are found using the flame ionization
detection. Lower detection limits can be obtained
for chlorinated hydrocarbons using the electron
capture detector.
14.2.2 A precision of + 5% (relative standard deviation)
can be readily achieved at concentrations 10
times the detection limit. Typical performance
data are included in Table 1.
14.2.3 Method accuracy is estimated to be within + 10%,
based on National Bureau of Standard calibrated
mixtures.
-------
T03-16
REFERENCES
1. Holdren, M., Spicer, C., Sticksel, P., Nepsund, K., Ward, G.,
and Smith, R., "Implementation and Analysis of Hydrocarbon
Grab Samples from Cleveland and Cincinnati 1981 Ozone Monitoring
Study", EPA-905/4-82-001. U.S. Environmental Protection Agency,
Research Triangle Park, North Carolina,1982.
2. Westberg, H., Rasmussen, R., and Holdren, M., "Gas Chromatographic
Analysis of Ambient Air for Light Hydrocarbons Using a Chemically
Bonded Stationary Phase", Anal. Chem. 46, 1852-1854, 1974.
3. Lonneman, W. A., "Ozone and Hydrocarbon Measurements in Recent
Oxidant Transport Studies", in Int. Conf. on Photochemical Oxidant
Pollutant and Its Control Proceedings, EPA-600/3-77-001a, 1977.
4. Singh, H., "Guidance for the Collection and Use of Ambient Hydrocarbon
Species Data in Development of Ozone Control Strategies", EPA-450/4-
80-008. U.S. Environmental Protection Agency, Research Triangle
Park, North Carolina, 1980.
5. Riggin, R. M., "Technical Assistance Document for Sampling and
Analysis of Toxic Organic Compounds in Ambient Air", EPA-600/4-83-027.
U.S. Environmental Protection Agency, Research Triangle Park,
North Carolina, 1983.
6. Annual Book of ASTM Standards, Part 11.03, "Atmospheric Analysis1,1
American Society for Testing and Materials, Philadelphia, Pennsylvania,
1983.
7. Foulger, B. E. and P. G. Sinamouds, "Drier for Field Use in the
Determination of Trace Atmospheric Gases", Anal. Chem., 51, 1089-1090,
1979.
8. Pheil, J. D. and W. A. McClenney, "Reduced Temperature Preconcentration
Gas Chromatographic Analysis of Ambient Vapor-Phase Organic Compounds:
System Automation", Anal. Chem., submitted, 1984.
9. Holdren, M. W0 W. A. McClenney, and R. N. Smith "Reduced Temperature
Preconcentration and Gas Chromatographic Analysis of Ambient Vapor-
Phase Organic Compounds: System Performance", Anal. Chem.,
submitted, 1984.
10. Holdren, M., S. Rust, R. Smith, and J. Koetz, "Evaluation of
Cryogenic Trapping as a Means for Collecting Organic Compounds in
Ambient Air", Draft Final Report on Contract No. 68-02-3487, 1984.
-------
T03-17
REFERENCES (Continued)
11. Cox R. D. and R. E. Earp,"Determination of Trace Level Organics
in Ambient Air by High-Resolution Gas Chromatography with
Simultaneous Photoiom'zation and Flame lonization Detection",
Anal. Chem. !54, 2265-2270, 1982.
12. Burns W. F., 0. T. Tingy, R. C. Evans and E. H. Bates,
"Problems with a Nafion® Membrane Dryer for Chromatographic
Samples", J. Chrom. 269, 1-9, 1983.
-------
T03-18
Sample Volume
Measuring Apparatus
Heated Sample Line
G.C. Carrier
Gas
Variac
Temperature
Controller
Sample Source
a. Fill Position
Sample Volume
Measuring Apparatus
Heated Sample Line
Sample Source
G.C. Carrier
Gas
.C. Column
Variac
Temperature
Controller
b. Injection Position
Figure 1. Schematic of Six-Port Valve Used for Sample
Collection.
-------
T03-19
Septum Seal
Glass/Teflon Valve
\ '
Pin hole Insertion,
Port or Septum
Injection Port
20 Liter
Teflon Bag
• Quick Connect
Sampling Port
Figure 2. Dilution Containers for Standard Mixtures
-------
Cryogenic
Sampling
Electronics
Console
Voltage to Solenoid
Liquid
Mass
Flow
Controller
Voltage to
Cartridge
Heaters
Vent
Gas Chromatographic System
o
oo
FIGURE 3. AUTOMATED SAMPLING AND ANALYSIS
SYSTEM FOR CRYOGENIC TRAPPING
-------
T03-21
Pump>
Vent
4 Way Bail Valve / Shut Off Valve
r-4
Helium Tank
Needle Valve
3 Position Valve
(1) Gas Chromatograph 6-Port Valve
(2) (Optional 2nd GC System)
(3) Off
(a) Volume Measuring Position
Pump,
Vent
4 Way Ball Valve
Shut Off Valve
Helium Tank
Ballast Tank
Needle Valve
3 Position Valve
(1) Gas Chromatograph 6-Port Valve
(2) (Optional 2nd GC System)
(3) Off
1 2
(b) Pump - Down Position
Figure 4. Sample Volume Measuring Apparatus
-------
TABLE 1. VOLATILE ORGANIC COMPOUNDS FOR WHICH THE CRYOGENIC SAMPLING
METHOD HAS BEEN EVALUATED^)
Compound
Vinylidene Chloride
Chloroform
1 ,2-Dichloroethane
Methyl chloroform
Benzene
Trichloroethylene
Tetrachl oroethyl ene
Chlorobenzene
Retention Time,
Minutes(b/
9.26
12.16
12.80
13.00
13.41
14.48
17.37
18.09
Test 1
(4 runs, 200cc
Mean
(ppb)
144
84
44
63
93
84
69
46
samples)
%RSD
4.4
3.8
3.7
4.5
4.0
3.7
3.7
3.3
Test 2
(8 runs, 200-cc
Mean
(ppb)
6.1
3.5
1.9
2.7
3.9
3.5
2.9
1.9
samples)
%RSD
3.9
5.8
5.1
4.9
5.1
4.1
4.3
3.2
a)Recovery efficiencies were 100 + 5% as determined by comparing direct sample loop (5cc) injections
with cryogenic collection techniques (using test 1 data). Data from reference 10.
b)GC conditions as follows:
Column - Hewlett Packard, crosslinked methyl silicone, 0.32 mm ID x 50 m long, thick
film, fused silica.
Temperature Program - 50°C for 2 minutes, then increased at 8°C/minute to 150°C.
I
CO
t-0
-------
METHOD T04 Revision 1.0
April, 1984
METHOD FOR THE DETERMINATION OF ORGANOCHLORINE PESTICIDES
AND POLYCHLORINATED BIPHENYLS IN AMBIENT AIR
1. Scope
1.1 This document describes a method for determination of a
variety of organochlorine pesticides and polychlorinated
biphenyls (PCBs) in ambient air. Generally, detection
3
limits of >1 ng/m are achievable using a 24-hour sampling
period.
1.2 Specific compounds for which the method has been employed
are listed in Table 1. Several references are available
which provide further details on the development and
application of the method. The sample cleanup and analysis
methods are identical to those described in U. S. EPA Method
608. That method is included as Appendix A of this methods
compendium.
2. Applicable Documents
2.1 ASTM Standards
D1356 Definition of Terms Related to
Atmospheric Sampling and Analysis (7).
2.2 Other Documents
Ambient Air Studies (1-3)
U. S. EPA Technical Assistance Document (4).
U. S. EPA Method 608 (5). See Appendix A of methods
compendium.
3. Summary of Method
3.1 A modified high volume sampler consisting of a glass
fiber filter with a polyurethane foam (PUF) backup
absorbent cartridge is used to sample ambient air at
a rate of -^200-280 L/minute.
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T04-2
3.2 The filter and PUF cartridge are placed in clean, sealed
containers and returned to the laboratory for analysis.
The PCBs and pesticides are recovered by Soxhlet extraction
with 5% ether in hexane.
3.3 The extracts are reduced in volume using Kuderna-Danish (K-D)
concentration techniques and subjected to column chroma-
tographic cleanup.
3.4 The extracts are analyzed for pesticides and PCBs using gas
chromatography with electron capture detection (GC-ECD), as
described in U. S. EPA Method 608 (5).
4. Significance
4.1 Pesticides, particularly organochlorine pesticides, are widely
used in both rural and urban areas for a variety of applications.
PCBs are less widely used, due to extensive restrictions placed
on their manufacture. However, human exposure to PCBs
continues to be a problem because of their presence in
various electrical products.
4.2 Many pesticides and PCBs exhibit bioaccumulative, chronic health
effects and hence monitoring ambient air for such compounds
is of great importance.
4.3 The relatively low levels of such compounds in the environment
requires the use of high volume sampling techniques to
acquire sufficient sample for analysis. However, the volatility
of these compounds prevents efficient collection on filter
media. Consequently, this method utilizes both a filter and
a PUF backup cartridge which provides for efficient collection
of most organochlorine pesticides, PCBs, and many other organics
within the same volatility range.
5. Definitions
Definitions used in this document and any user-prepared SOPs
should be consistent with ASTM D1356 (7). All abbreviations
-------
T04-3
and symbols are defined within this document at the point of
use.
6. Interferences
6.1 The use of column chromatographic cleanup and selective GC
detection (GC-ECD) minimizes the risk of interference from
extraneous organic compounds. However, the fact that PCBs
as well as certain organochlorine pesticides (e.g. toxaphene
and chlordane) are complex mixtures of individual compounds
can cause difficulty in accurately quantifying a particular
formulation in a multiple component mixture.
6.2 Contamination of glassware and sampling apparatus with traces
of pesticides or PCBs can be a major source of error in the
method, particularly when sampling near high level sources
(e.g. dumpsites, waste processing plants, etc.) careful attention
to cleaning and handling procedures is required in all steps
of the sampling and analysis to minimize this source of error.
7. Apparatus
7.1 Hi-Vol Sampler with PDF cartridge - available from General
Metal Works (Model PS-1). See Figure 1.
7.2 Sampling Head to contain glass cartridge with PUF plug - available
from General Metal Works. See Figure 2.
7.3 Calibration orifice - available from General Metal Works.
7.4 Manometer - to use with calibration orifice.
7.5 Soxhlet extraction system - including Soxhlet extractors
(500 and 250 ml), heating mantels, variable voltage trans-
formers, and cooling water source - for extraction of PUF
cartridges before and after sampling. Also for extraction of
filter samples.
7.6 Vacuum oven connected to water aspirator - for drying
extracted PUF cartridges.
7.7 Gas chromatograph with electron capture detector - (consult
U. S. EPA Method 608 for specifications).
-------
T04-4
7.8 Forceps - to handle quartz fiber filter samples.
7.9 Die - to cut PUF plugs.
7.10 Various items for extract preparation, cleanup, and analysis
consult U. S. EPA Method 608 for detailed listing.
7.11 Chromatography column - 2 mm I.D. x 15 cm long - for alumina
cleanup.
8. Reagent and Materials
8.1 Polyurethane foam - 3 inch thick sheet stock, polyether
type used in furniture upholstering. Density 0.022 g/cm .
8.2 Polyester gloves - for handling PUF cartridges and filters
8.3 Filters, quartz fiber - Pallflex 2500 QAST , or equivalent.
8.4 Wool felt filter - 4.9 mg/cm2 and 0.6 mm thick. To fit
sample head for collection efficiency studies. Pre-
extracted with 5% diethyl ether in hexane.
8.5 Hexane - Pesticide or distilled in glass grade.
8.6 Diethyl ether - preserved with 2% ethanol - distilled in
glass grade, or equivalent.
8.7 Acetone - Pesticide or distilled in glass grade.
8.8 Glass container for PUF cartridges.
8.9 Glass petri dish - for shipment of filters to and from the
laboratory.
8.10 Ice chest - to store samples at M)°C after collection.
8.11 Various materials needed for extract preparation, cleanup,
and analysis - consult U. S. EPA Method 608 for details
(Appendix A of this compendium).
8.12 Alumina - activity grade IV. 100/200 mesh
9. Assembly and Calibration of Sampling Apparatus
9.1 Description of Sampling Apparatus
9.1.1 The entire sampling system is diagrammed in Figure 1.
This sampler was developed by Syracuse University
-------
T04-5
Research Corporation (SURC) under a U. S. EPA
contract (6) and further modified by Southwest
Research Institute and the U. S. EPA. A unit
specifically designed for this method is now commer-
cially available (Model PS-1 - General Metal Works,
Inc., Village of Cleves, Ohio). The method
writeup assumes the use of the commercial device,
although the earlier modified device is also con-
sidered acceptable.
9.1.2 The sampling module (Figure 2) consists of a glass
sampling cartridge and an air-tight metal cartridge
holder. The PUF plug is retained in the glass
sampling cartridge.
9.2 Calibration of Sampling System
9.2.1 The airflow through the sampling system is monitored
by a venturi/Manehelic assembly, as shown in Figure 1.
A multipoint calibration of the venturi/mag-
nehelic assembly must be conducted every six months
using an audit calibration orifice, as described in
the U. S. EPA High Volume Sampling Method (8). A
single point calibration must be performed before
and after each sample collection, using the procedure
described below.
9.2.2 Prior to calibration a "dummy" PUF cartridge and
filter are placed in the sampling head and the sampling
motor is activated. The flow control valve is
fully opened and the voltage variator is adjusted
so that a sample flow rate corresponding to i/110% of
the desired flow rate is indicated on the magnehelic
(based on the previously obtained multipoint cali-
bration curve). The motor is allowed to warmup
for VI0 minutes and then the flow control valve is
adjusted to achieve the desired flow rate. The
ambient temperature and barometric pressure should
-------
T04-6
be recorded on an appropriate data sheet (e.g. Figure 3)
9.2.3 The calibration orifice is then placed on the sampling
head and a manometer is attached to the tap on the
calibration orifice. The sampler is momentarily
turned off to set the zero level of the manometer.
The sampler is then switched on and the manometer
reading is recorded, once a stable reading is
achieved. The sampler is then shut off.
9.2.4 The calibration curve for the orifice is used to
calculate sample flow from the data obtained in
9.2.3, and the calibration curve for the venturi/
magnehelic assembly is used to calculate sample
flow from the data obtained in 9.2.2. The calibra-
tion data should be recorded on an appropriate
data sheet (e.g. Figure 3). If the two values do
not agree within 10% the sampler should be inspected
for damage, flow blockage, etc. If no obvious problems
are found the sampler should be recalibrated (multi-
point) according to the U. S. EPA High Volume
Sampling procedure (8).
9.2.5 A multipoint calibration of the calibration orifice,
against a primary standard, should be obtained
annually.
10. Preparation of Sampling (PUF) Cartridges
10.1 The PUF adsorbent is a polyether-type polyurethane foam
(density No. 3014 or 0.0225 g/cm3). This type of foam
is used for furniture upholstery. It is white and yellows
on exposure to light.
10.2 The PUF inserts are 6.0 cm diameter cylindrical plugs cut
from 3 inch sheet stock and should fit with slight com-
pression in the glass cartridge, supported by the wire
-------
T04-7
screen. See Figure 2. During cutting the die is rotated
at high speed (e.g. in a drill press) and continuously
lubricated with water.
10.3 For initial cleanup the PUF plug is placed in a Soxhlet
extractor and extracted with acetone for 14-24 hours at
approximately 4 cycles per hour. When cartridges are
reused, 5% diethyl ether in n-hexane can be used as the
cleanup solvent.
10.4 The extracted PUF is placed in a vacuum oven connected
to a water aspirator and dried at room temperature for
approximately 2-4 hours (until no solvent odor is detected).
10.5 The PUF is placed into the glass sampling cartridge using
polyester gloves. The module is wrapped with hexane
rinsed aluminum foil, placed in a labeled container
and tightly sealed.
10.6 Other adsorbents may be suitable for this method as indicated
in the various references (1-3). If such materials are
employed the user must define appropriate preparation
procedures based on the information contained in these
references.
10.7 At least one assembled cartridge from each batch must be
analyzed, as a laboratory blank, using the procedures
described in Section 12, before the batch is considered
acceptable for field use. A blank level of <10 ng/plug
for single compounds is considered to be acceptable. For
multiple component mixtures (e.g. Arochlors) the blank level
should be <100 ng/plug.
11. Sampling
11.1 After the sampling system has been assembled and calibrated
as described in Section 9 it can be used to collect air
samples as described below.
11.2 The samples should be located in an unobstructed area, at
least two meters from any obstacle to air flow. The
exhaust hose should be stretched out in the downwind
-------
T04-8
direction to prevent recycling of air.
11.3 A clean sampling cartridge and quartz fiber filter are removed
from sealed transport containers and placed in the sampling
head using forceps and gloved hands. The head is tightly sealed
into the sampling system. The aluminum foil wrapping is
placed back in the sealed container for later use.
11.4 The zero reading of the Magnehelic is checked. Ambient
temperature, barometric pressure, elapsed time meter setting,
sampler serial number, filter number and PUF cartridge number
are recorded. A suitable data sheet is shown in Figure 4.
11.5 The voltage variator and flow control valve are placed at the
settings used in 9.2.3 and the power switch is turned on.
The elapsed time meter is activated and the start time recorded.
The flow (Magnehelic setting) is adjusted, if necessary using
the flow control valve.
11.6 The Magnehelic reading is recorded every six hours during
the sampling period. The calibration curve (Section 9.2.7) is
used to calculate the flow rate. Ambient temperature and
barometric pressure are recorded at the beginning and end of
the sampling period.
11.7 At the end of the desired sampling period the power is turned
off and the filter and PUF cartridges are wrapped with the
original aluminum foil and placed in sealed, labeled containers
for transport back to the laboratory.
11.8 The Magnehelic calibration is checked using the calibration
orifice as described in Section 9.2.4. If the calibration
deviates by more than 10% from the initial reading the flow data
for that sample must be marked as suspect and the sampler
should be inspected and/or removed from service.
11.9 At least one field blank will be returned to the laboratory
with each group of samples. A field blank is treated exactly
as a sample except that no air is drawn through the cartridge.
-------
T04-9
11.10 Samples are stored at ^20°C in an ice chest until receipt at
the analytical laboratory, at which time they are stored
refrigerated at 4°C.
12. Sample Preparation and Analysis
12.1 Sample Preparation
12.1.1 All samples should be extracted within 1 week after
collection.
12.1.2 PDF cartridges are removed from the sealed con-
container using gloved hands, the aluminum foil
wrapping is removed, and the cartridges are placed
into a 500-mL Soxhlet extraction. The cartridges are
extracted for 14-24 hours at ^4 cycles/hour with 5%
diethyl ether in hexane. Extracted cartridges can be
dried and reused following the handling procedures
in Section 10. The quartz filter can be placed in
the extractor with the PUF cartridges. However, if
separate analysis is desired then one can proceed with
12.1.3.
12.1.3 If separate analysis is desired, quartz filters are
placed in a 250-mL Soxhlet extractor and extracted
for 14-24 hours with 5% diethyl ether in hexane.
12.1.4 The extracts are concentrated to 10 ml final
volume using 500-mL Kuderna-Danish concentrators
as described in EPA Method 608 (5), using a hot water
bath. The concentrated extracts are stored refrigerated
in sealed 4-dram vials having teflon-lined screw-caps
until analyzed or subjected to cleanup.
12.2 Sample Cleanup
12.2.1 If only organochlorine pesticides and PCBs are sought,
an alumina cleanup procedure reported in the literature
is appropriate (1). Prior to cleanup the sample
-------
T04-10
extract is carefully reduced to 1 ml using a gentle
steam of clean nitrogen.
12.2.2 A glass chromatographic column (2 mm ID x 15 cm long)
is packed with alumina, activity grade IV and rinsed
with ^20 ml of n-hexane. The concentrated sample
extract (from 12.2.1) is placed on the column and
eluted with 10 ml of n-hexane at a rate of 0.5
mL/minute. The eluate volume is adjusted to
exactly 10 mL and analyzed as described in 12.3.
12.2.3 If other pesticides are sought, alternate cleanup
procedures (e.g. Florisil) may be required. Method
608 (5) identifies appropriate cleanup procedures.
12.3 Sample Analysis
12.3.1 Sample analysis is performed using GC/ECD as
described in EPA Method 608 (5). The user must
consult this method for detailed analytical procedures.
12.3.2 GC retention times and conditions are identified
in Table 1 for the compounds of interest.
13. GC Calibration
Appropriate calibration procedures are identified in EPA Method
608 (5).
14. Calculations
14.1 The total sample volume (\fn) is calculated from the
periodic flow readings (Magnehelic) taken in Section
11.6 using the following equation.
Q, + Qp ... QN T
Mn= —! -x
N 1000
where
-------
T04-11
3
V = Total sample volume (m ).
Q,, O-.-.Q^ = Flow rates determined at the
beginning, end, and intermediate points during
sampling (L/minute).
N = Number of data points averaged.
T = Elapsed sampling time (minutes).
14.2 The volume of air sampled can be converted to standard
conditions (760 mm Hg pressure and 25°C) using the following
equation:
p
A
V = V X
s m
760 273+tA
where
V = Total sample volume at 25°C and 760 mm Hg
3
pressure (m )
V = Total sample flow under ambient conditions (m )
P^ = Ambient pressure (mm Hg)
t . = Ambient temperature (°C)
14.3 The concentration of compound in the sample is calculated
using the following equation:
A x Vc
CA =
V.XVS
where
C. = Concentration of analyte in the sample,
3
yg/m
A = Calculated amount of material injected onto
the chromatograph based on calibration curve
for injected standards (nanograms)
V.j = Volume of extract injected (yL).
-------
T04-12
V = Final volume of extract (ml).
V = Total volume of air samples corrected to
•* o
standard conditions (m ).
14. Performance Criteria and Quality Assurance
This section summarizes the quality assurance (QA) measures and
provides guidance concerning performance criteria which should
be achieved within each laboratory.
14.1 Standard Operating Procedures (SOPs)
14.1.1 Users should generate SOPs describing the follow-
ing activities as accomplished in their laboratory:
1) assembly, calibration and operation of the
sampling system, 2) preparation, purification, storage
and handling of sampling cartridges, 3) assembly,
calibration and operation of the GC/ECD system, and
4) all aspects of data recording and processing.
14.1.2 SOPs should provide specific stepwise instructions
and should be readily available to, and understood
by, the laboratory personnel conducting the work.
14.2 Process, Field, and Solvent Blanks
14.2.1 One PUF cartridge and filter from each batch of
approximately twenty should be analyzed, without
shipment to the field, for the compounds of
interest to serve as a process blank.
14.2.2 During each sampling episode at least one PUF
cartridge and filter should be shipped to the field
and returned, without drawing air through the sampler,
to serve as a field blank.
14.2.3 During the analysis of each batch of samples at
least one solvent process blank (all steps conducted
but no PUF cartridge or filter included) should be
-------
T04-13
carried through the procedure and analyzed.
14.2.4 Blank levels should not exceed ^10 ng/sample for
single components or MOO ng/sample for multiple
component mixtures (e.g. PCBs).
14.3 Collection Efficiency and Spike Recovery
14.3.1 Before using the method for sample analysis each
laboratory must determine their collection
efficiency for the components of interest.
14.3.2 The glass fiber filter in the sampler is replaced
with a hexane-extracted wool felt filter (weight
2
14.9 mg/cm , 0.6 mm thick). The filter is spiked
with microgram amounts of the compounds of interest
by dropwise addition of hexane solutions of the
compounds. The solvent is allowed to evaporate
and filter is placed into the sampling system for
immediate use.
14.3.3 The sampling system, including a clean PUF cartridge,
is activated and set at the desired sampling flow
rate. The sample flow is monitored for 24 hours.
14.3.4 The filter and PUF cartridge are then removed and
analyzed as described in Section 12.
14.3.5 A second sample, unspiked is collected over the
same time period to account for any background
levels of components in the ambient air matrix.
14.3.6 A third PUF cartridge is spiked with the same amounts
of the compounds used in 14.3. 2 and extracted to
determine analytical recovery.
14.3.7 In general analytical recoveries and collection
efficiencies of 75% are considered to be acceptable
method performance.
-------
T04-14
14.3.8 Replicate (at least triplicate) determinations of
collection efficiency should be made. Relative
standard deviations for these replicate determinations
of + 15% or less is considered acceptable performance.
14.3.9 Blind spiked samples should be included with sample
sets periodically, as a check on analytical per-
formance.
14.4 Method Precision and Accuracy
Typical method recovery data are shown in Table 1. Re-
coveries for the various chlorobiphenyls illustrate the
fact that all components of an Arochlor mixture will not
be retained to the same extent. Recoveries for tetrachloro-
biphenyls and above are generally greater than 85% but
di- and trichloro homologs may not be recovered quantitatively,
-------
T04-15
REFERENCES
1. Lewis, R. G., Brown, A. R., and Jackson, M. D., "Evaluation
of Polyurethane Foam for Sampling of Pesticides, Polychlorinated
Biphenyls, and Polychlorinated Naphthalenes in Ambient Air",
Anal. Chem. 49, 1668-1672, 1977.
2. Lewis, R. G. and Jackson, M. D., "Modification and Evaluation
of a High-Volume Air Sampler for Pesticides and Semi volatile
Industrial Organic Chemicals", Anal. Chem. j>4, 592-594, 1982.
3. Lewis, R. G., Jackson, M. D., and MacLeod, K. E., "Protocol for
Assessment of Human Exposure to Airborne Pesticides", EPA-600/2-80-
180, U.S. Environmental Protection Agency, Research Triangle
Park, NC, 1980.
4. Riggin, R. M., "Technical Assistance Document for Sampling and
Analysis of Toxic Organic Compounds in Ambient Air", EPA-600/4-
83-027., U. S. Environmental Protection Agency, Research Triangle
Park, NC, 1983.
5. Longbottom, J. E. and Lichtenberg, J. J., "Methods for Organic
Chemical Analysis of Municipal and Industrial Wastewater",
EPA-600/4-82-057, U. S. Environmental Protection Agency,
Cincinnati, OH, 1982.
6. Bjorkland, J., Compton, B., and Zweig, G., "Development of
Methods for Collection and Analysis of Airborne Pesticides."
Reportfor Contract No. CPA 70-15, National Air Pollution Control
Association, Durham, NC, 1970.
7. Annual Book of ASTM Standards, Part 11.03, "Atmospheric Analysis",
American Society for Testing and Materials, Philadelphia, PA,
1983.
8. Reference Method for the Determination of Suspended Particulates
in the Atmosphere (High Volume Method). Federal Register,
Sept. 14, 1972 or 40CFR50 Appendix B.
-------
T04-16
TABLE 1. SELECTED COMPONENTS DETERMINED USING HI-VOL/PUF SAMPLING PROCEDURE
24-Hour Sampling Efficiency(b)
GC Retention
Compound Time, Minutes'9)
Aldrin 2.4
4,4'-DDE 5.1
4,4'-DDT 9.4
Chlordane (c)
Chlorobiphenyls
4,4' Di-
2,4,5 Tri-
2, 4', 5 Tri-
2,2' ,5,5' Tetra-
2, 2', 4, 5, 5' Penta-
2, 2', 4, 4', 5, 5' Hexa
Air
Concentration
ng/m^
0.3-3.0
0.6-6.0
1.8-18
15-150
2.0-20
0.2-2.0
0.2-2.0
0.2-2.0
0.2-2.0
0.2-2.0
%
Recovery
28
89
83
73
62
36
86
94
92
86
(a) Data from U.S. EPA Method 608. Conditions are as follows:
Stationary Phase - 1.5% SP2250/1.95% SP-2401 on
Supelcoport (100/120 mesh) packed in 1.8 mm long x
4 mm ID glass column.
Carrier - 5/95 methane/Argon at 60 mL/Minute
Column Temperature - 160°C except for PCBs which are
determined at 200°C.
(b) From Reference 2.
(c) Multiple component formulation. See U.S. EPA Method 608.
-------
T04-17
Magnehehc
Gauge
0-100 in.
Sampling
Head
(See Figure 2)
Exhaust
Duct
(6 in. xlOft)
Voltage Variator
Elapsed Time Meter
FIGURE 1. HIGH VOLUME AIR SAMPLER. AVAILABLE
FROM GENERAL METAL WORKS (MODEL PS-1)
-------
O
I
lU
tC
-------
Performed by_
Date/Time
Calibration Orifice
Manometer S/N
S/N
Ambient Temperature_
Bar.Press.
Hg
Sampler
S/N
VaHac
Setting V
Timer OK?
Yes/Ho
Calibration Orifice
Data
Manometer,
in. H20
Flow Rate,
scm /min(a)
Sampler
Venturi Data
Magnehelic,
in. H20
Flow Rate
scm/min (b)
% Difference Between
Calibration and Sample
Venturi Flow Rates
Comments
o
-C-
I
(a) From Calibration Tables for Calibration Orifice or Venturi Tube
(b) From Calibration Tables for Venturi Tube in each H1-Vol unit.
Date check by
Date
FIGURE 3. TYPICAL CALIBRATION SHEET FOR HIGH VOLUME SAMPLER
-------
S«mpl*r
S/N
Sampling Location
1 D
N«w
FrttM K/t
PUFCart
No
Vance
Setting
Clock Tim*
Stari, hf CDT
Stop, hf CDT
Mm Elapsed
Sampler Timer
Start, mm
Stop mm
Mm Elapsed
Ventur. Rmdmy Tima/Maynat>«4tc in H2O
1
2
3
4
Ambiant
Temperature, "C
Start
Stop
Barometric
Prassurt mm Hg
Start
Stop
•=«-"—
o
J^
I
NJ
O
(a) Record iny flvtifonc* of Umpiring with Mmplvr and/or •bnormihtiM in wmplcr op«r«tion, PUF cartridge condition or handling, ate
Data Chackad By.
FIGURE 4. TYPICAL SAMPLING DATA FORM FOR HIGH VOLUME PESTICIDE/PCB SAMPLER
-------
METHOD T05 Revision 1.0
April, 1984
METHOD FOR THE DETERMINATION OF ALDEHYDES AND KETONES IN AMBIENT AIR
USING HIGH PERFORMANCE LIQUID CHROMATOGRAPHY (HPLC)
1. Scope
1.1 This document describes a method for determination of
individual aldehydes and ketones in ambient air. With
careful attention to reagent purity and other factors
the method can detect most monofunctional aldehydes and
ketones at the 1-2 ppbv level.
1.2 Specific compounds for which the method has been employed
are listed in Table 1. Several studies have used the
same basic method, with minor procedural differences,
for analysis of ambient air (1-3).
2. Applicable Documents
2.1 ASTM Standards:
D 1356 Definitions of Terms Related to Atmospheric
Sampling and Analysis (s)
2.2 Other Documents
Ambient air studies (1-3).
U.S. EPA Technical Assistance Document (4)
3. Summary of Method
3.1 Ambient air is drawn through a midget impinger containing 10 mL
of 2N^ HC1/0.05% 2,4-dinitrophenylhydrazine (DNPH reagent)
and 10 mL of isooctane. Aldehydes and ketones readily
form stable 2,4-dinitrophenylhydrazones (DNPH derivatives).
-------
T05-2
3.2 The impinger solution is placed in a screw-capped vial having
a teflon-lined cap and returned to the laboratory for analysis.
The DNPH derivatives are recovered by removing the isooctane
layer, extracting the aqueous layer with 10 ml of 70/30
hexane/methylene chloride, and combining the organic
layers.
3.3 The combined organic layers are evaporated to dryness under
a steam of nitrogen and the residue dissolved in methanol.
3.4 The DNPH derivatives are determined using reversed phase
HPLC with an ultraviolet (UV) adsorption detector operated
at 370 nm.
4. Significance
4.1 Aldehydes and ketones are emitted into the atmosphere from
chemical operations and various combustion sources. In
addition, several of these compounds (e.g. formaldehyde and
acetaldehyde) are produced by photochemical degradation
of other organic compounds. Many of these compounds are
acutely toxic and/or carcinogenic, thus requiring their
determination in ambient air in order to assess human
health impacts.
4.2 Conventional methods for aldehydes and ketones have generally
employed colorimetric techniques wherein only one or two
compounds are detected, or the sum of numerous compounds
is determined. The method described herein provides a
means for specifically determining a wide variety of aldehydes
and ketones at typical ambient concentrations.
5. Definitions
Definitions used in this document and any user prepared SOPs
should be consistent with ASTM 01356(5). All abbreviations and
symbols are defined within this document at the point of use.
-------
T05-3
6. Interferences
6.1 The only significant interferences in the method are certain
isomeric aldehydes or ketones which may be unresolved by
the HPLC system. Such interferences can often be overcome by
altering the separation conditions (e.g. using alternate
HPLC columns or mobile phase compositions).
6.2 Formaldehyde contamination of the DNPH reagent is a
frequently encountered problem. The reagent must be
prepared within 48 hours before use and must be stored in
an uncontaminated environment before and after sampling to
minimize blank problems. Acetone contamination is
apparently unavoidable. Consequently, the method cannot be
used to accurately measure acetone levels except in highly
contaminated environments.
7. Apparatus
7.1 Isocratic HPLC system-consisting of high pressure
pump, injection valve, Zorbax ODS column (25 cm x 4.6 mm ID),
variable wavelength UV detector, and data system or
stripchart recorded. See Figure 3.
7.2 Sampling system-capable of accurately and precisely
sampling 100-1000 mL/minute of ambient air. See Figure 1.
7.3 Stopwatch
7.4 Friction top metal can e.g. one-gallon (paint can) - to hold
ONPH reagent and samples
7.5 Thermometer - to record ambient temperature.
7.6 Barometer (optional)
7.7 Analytical balance - 0.1 mg sensitivity
7.8 Reciprocating shaker
7.9 Midget impingers - jet inlet type - 25 mL volume.
7.10 Ice bath - for cooling impingers during sampling.
-------
T05-4
7.11 Nitrogen evaporator with heating block - for concentrating
samples
7.12 Suction filtration apparatus - for filtering HPLC
mobile phase.
7.13 Volumetric flasks - 100 ml and 500 ml.
7.14 Pipettes - various sizes, 1-10 ml.
7.15 Helium purge line (optional) - for degassing HPLC
mobile phase.
7.16 Erlenmeyer flask, 1-liter - for preparing HPLC mobile
phase.
7.17 Graduated cylinder, 1 liter - for preparing HPLC mobile
phase.
7.18 Microliter syringe, 10-25 uL - for HPLC injector.
8. Reagents and Materials
8.1 Bottles, 10 oz. glass, with teflon-lined screw cap - for
storing DNPH reagent.
8.2 Vials, 50 mL, with teflon-lined screw cap - for holding
samples and extracts.
8.3 Disposable pipettes and bulbs.
8.4 Granular charcoal.
8.5 Methanol, hexane, methylene chloride, isooctane - distilled
in glass or pesticide grade.
8.6 2,4-Dinitrophenylhydrazine - highest purity available
(20% moisture).
8.7 Nitrogen, compressed gas cylinder -99.99% purity for
sample evaporation.
8.8 Polyester filters, 0.22 ym - Nuclepore or equiv.
8.9 DNPH derivatives of the components of interest -
synthesized from DNPH and neat aldehydes according
to reference (7). Recrystallized from ethanol before
use.
-------
T05-5
9. Preparation of DNPH Reagent
9.1 Each batch of DNPH reagent should be prepared and purified
within 48 hours of sampling, according to the procedure
described in this section.
9.2 Two hundred and fifty milligrams of solid 2,4-dinitro-
phenylhydrazine and 90 ml of concentrated hydrochloric
acid are placed into a 500 mL volumetric flask and the
flask is filled to the mark with reagent water. The
flask is then inverted several times or sonified until all of
the solid material has dissolved.
9.3 Approximately 400 mL of the DNPH reagent is placed in a
16 ounce glass screw-capped bottle having a teflon-lined
cap. Approximately 50 ml of a 70/30 (V/V) hexane/methylene
chloride mixture is added to the bottle and the capped
bottle is shaken for 15 minutes on a reciprocating shaker.
The organic layer is then removed and discarded by decanting
as much as possible and using a disposable pipette to
remove the remaining organic layer.
9.4 The DNPH reagent is extracted two more times as described
in 9.3. The bottle is then tightly capped, sealed with
teflon tape, and placed in a friction top can (paint can)
containing a 1-2 inch layer of granulated charcoal. The
bottle is kept in the sealed can prior to use.
9.5 A portion of the DNPH reagent is analyzed using the
procedure described in Section 11 prior to use in order to
ensure that adequate background levels are maintained.
10. Sampling
10.1 The sampling apparatus is assembled and should be similar to
that shown in Figure 1. EPA Method 6 uses essentially the same
sampling system (8). All glassware (e.g. impingers, sampling
bottles, etc.) must be thoroughly rinsed with methanol and oven
dried before use.
-------
T05-6
10.2 Prior to sample collection the entire assembly (including
empty sample impingers) is installed and the flow rate
checked at a value near the desired rate. In general
flow rates of 100-1000 mL/minute are useful. Flow rates
greater than ^1000 mL/minute should not be used because
impinger collection efficiency may decrease. Generally
calibration is accomplished using a soap bubble flow
meter or calibrated wet test meter connected to the flow
exit, assuming the entire system is sealed. ASTM Method
D3686 describes an appropriate calibration scheme not
requiring a sealed flow system downstream of the pump.
10.3 Ideally a dry gas meter is included in the system to record
total flow. If a dry gas meter is not available the operator
must measure and record the sampling flow rate at the
beginning and end of the sampling period to determine
sample volume. If the sampling period exceeds two hours
the flow rate should be measured at intermediate points
during the sampling period. Ideally a rotameter should be
included to allow observation of the flow rate without
interruption of the sampling process.
10.4 To collect an air sample two clean midget impingers are
loaded with 10 ml of purified DNPH reagent and 10 mL of
isooctane. The impingers are connected in series to
the sampling system and sample flow is started. The follow-
ing parameters are recorded on the data sheet (see Figure 3
for an example): date, sampling location, time, ambient
temperature, barometric pressure (if available), relative
humidity (if available), dry gas meter reading (if appro-
priate), flow rate, rotometer setting, DNPH reagent batch
number, and dry gas meter and pump identification numbers.
10.5 The sampler is allowed to operate for the desired period,
with periodic recording of the variables listed above.
The total flow should not exceed %80 liters. The operator
must ensure that at least 2-3 ml of isooctane remains in
the first impinger at the end of the sampling interval
(i.e. for high ambient temperatures lower sampling volumes
may be required).
-------
T05-7
10.6 At the end of the sampling period the parameters listed
in 10.4 are recorded and the sample flow is stopped. If
a dry gas meter is not used the flow rate must be checked
at the end of the sampling interval. If the flow rate
at the beginning and end of the sampling period differ
by more than 15% the sample should be marked as suspect.
10.7 Immediately after sampling the impingers are removed from
the sampling system. The contents of the first impinger
are emptied into a clean 50 mL glass vial having a teflon-
lined screw cap. The first impinger is then rinsed with
the contents of the second (backup) impinger and the rinse
solution is added to the vial. The vial is then capped,
sealed with teflon tape and placed in a friction top can
containing 1-2 inches of granular charcoal. The samples
are stored in the can, refrigerated until analysis.
10.8 If a dry gas meter or equivalent total flow indicator is
not used the average sample flow rate must be calculated
according to the following equation:
Q QT+QZ-.-.QN
A N
where
0. = Average flow rate in mL/minute.
Q,, Qp,...QN= Flow rates determined at the
beginning, end, and intermediate
points during sampling.
N = Number of points averaged.
10.9 The total flow is then calculated using the following
equation:
1000
Vm= Total volume sampled in liters at measured
temperature and pressure
Tp = Stop time
T-| = Start time (To-T-, given in minutes)
-------
T05-8
11. Sample Analysis
11.1 Sample Preparation
11.1.1 The samples are returned to the laboratory in
50 ml screw-capped glass vials. To recover the
DNPH derivatives the following procedure is em-
ployed.
11.1.2 The vials are shaken in a horizontal position on
a reciprocating shaker for 10 minutes. The vials
are then removed from the shaker and the isooctane
layer is removed and placed in a second clean 50 ml
screw-capped glass vial using a disposable pipette.
11.1.3 The remaining aqueous layer is extracted with 10 ml
of 70/30 (V/V) hexane/methylene chloride in the
same manner as described in 11.1.2. The organic
layer is removed and combined with the isooctane
extract.
11.1.4 The combined organic extracts are then concentrated
to dryness at 40°C under a steam of pure nitrogen.
When the sample just reaches dryness the vial is
removed from the nitrogen stream and a measured
volume (2-5 ml) of methanol is added to the vial.
The vial is tightly capped and stored refrigerated
until analysis.
11.2 HPLC Analysis
11.2.1 The instrument is assembled and calibrated as described
in Section 12. Prior to each analysis the detector
baseline is checked to ensure stable operation.
11.2.2 A 5-25 U.L aliquot of the sample, dissolved in
methanol,is drawn into a clean HPLC injection syringe.
The sample injection loop is loaded and an injection
is made. The data system, if available, is activated
simultaneously with the injection and the point of
injection is marked on the stripchart recorder.
-------
T05-9
11.2.3 After approximately one minute, the injection valve
is returned to "load" position and the syringe and
valve are flushed with methanol in preparation for
the next sample analysis.
11.2.4 After elution of the last component of interest the
acquisition is terminated and the component concen-
trations are calculated as described in Section 13.
11.2.5 After a stable baseline is achieved the system can
be used for further sample analyses as described above.
11.2.6 If the concentration of a component exceeds the linear
range of the instrument the sample should be diluted
with methanol, or a smaller volume can be injected
onto the HPLC.
12. HPLC Assembly and Calibration
12.1 The HPLC system is assembled as shown in Figure 3. The
typical chromatographic performance and operating para-
meters are shown in Figure 4.
12.2 Mobile phase is prepared by mixing 800 mL of methanol and
200 mL of reagent water. This mixture is filtered through
a 0.22 ym polyester membrane filter in an all glass and
teflon suction filtration apparatus. The filtered mobile
phase is degassed by purging with helium gas for 10-15
minutes (^ 100 mL/minute) or by heating to 'v60°C for 5-10
minutes in an Erlenmeyer flask covered with a watch glass. A
constant back pressure restrictor (^ 50 psi) or short length
(6-12 inches) of 0.01 inch I.D. teflon tubing should be
placed after the detector to further eliminate mobile phase
outgassing.
12.3 The mobile phase is placed in the HPLC solvent reservoir and
the pump flow is set at 1 mL/minute and allowed to pump
for 20-30 minutes prior to the first analysis. The detector
is switched on at least 30 minutes prior to the first
analysis and the detector output is displayed on a stripchart
recorder or similar output device at a sensitivity of .008
-------
T05-10
absorbance units full scale (AUFS). Once a stable baseline
is achieved the system is ready for calibration.
12.4 Calibration standards are prepared in methanol from the
solid DNPH derivatives. Individual stock solutions of
^ 100 mg/L are prepared by dissolving 10 mg of the solid
derivative in 100 mL of methanol. These individual solutions
are used to prepare calibration standards containing all of
the derivatives of interest at concentrations of 0.1 - 10 mg/L,
which spans the concentration of interest for most ambient
air work.
12.5 All calibration runs are performed as described for sample
analyses in Section 11. Before initial use the operator
should inject a series of calibration standards (at least
three levels) spanning the concentration range of interest.
Using the UV detector, a linear response range of approximately
0.1 to 10 mg/L should be achieved, for ^ 10 pL injection
volumes. Linear response is indicated where a correlation
coefficient of a least 0.999 for a linear least squares
fit of the data (concentration versus area response) is
obtained.
12.6 Once linear response has been documented an intermediate
concentration standard near the anticipated levels for each
component, but at least 10 times the detection limit, should
be chosen for daily calibration. The response for the various
DNPH components should be within 10% day to day. If greater
variability is observed more frequent calibration may be
required to ensure that valid results are obtained.
12.7 The response for each component in the daily calibration
standard is used to calculate a response factor according
to the following equation:
cc x v
RF =
\*
Rc
-------
T05-11
where
RF = response factor for the component of
interest in nanograms injected/response
unit (usually area counts).
C = concentration of component in the daily
t*
calibration standard (mg/L).
Vj = volume of calibration standard injected (yL)
R = response for component of interest in
calibration standard (area counts).
13.
Calculations
13.1 The volume of air sampled is often reported uncorrected for
atmospheric conditions (i.e. under ambient conditions).
However, the value can be adjusted to standard conditions
(25°C and 760 mm pressure) using the following equation:
P. 298
Vs= Vm x -£ x
760 273 + T,
where
Vs = total sample volume at 25°C and 760 mm Hg
pressure (liters).
Vm = total sample volume under ambient conditions
(liters). Calculated in 10.9 or from dry gas
meter reading.
P/\ = ambient pressure (mmHg).
TA = ambient temperature (°C).
13.2 The concentration of each aldehyde (as the DNPH derivative is
calculated for each sample using the following equation:
-------
T05-12
W . = RF,, X R . X —
d C d
where
W, = total quantity of derivative in the sample
RF = response factor calculated in 12.7
R, = response for component in sample extract
(area counts or other response units).
Vr = final volume of sample extract (ml).
Vj = volume of extract injected onto the HPLC
system (ML).
13.3 The concentration of aldehyde in the original sample is
calculated from the following equation:
W , MW,,
C = - 9 - x —2- X 1000
where
CA = concentration of aldehyde in the original
sample (ng/L).
V^ or V$ are as specified in Section 13.1.
MW. and MWd are the molecular weights (g/mole) of
the aldehyde and its corresponding DNPH derivative,
respectively.
13.4 The aldehyde concentrations can be converted to ppbv using
the following equation:
24.4
C(ppbv) = C.(ng/L) X -
where
C«(ng/L) is calculated using Vs.
-------
T05-13
14. Performance Criteria and Quality Assurance
This section summarizes the quality assurance (QA) measures and
provides guidance concerning performance criteria which should
be achieved within each laboratory.
14.1 Standard Operating Procedures (SOPs).
14.1.1 Each user should generate SOPs describing the
following activities as accomplished in their
laboratory: 1) assembly, calibration and operation
of the sampling system, 2) preparation, purification,
storage and handling of DNPH reagent and samples, 3)
assembly, calibration and operation of the HPLC
system, and 4) all aspects of data recording and
processing.
14.1.2 SOPs should provide specific stepwise instructions
and should be readily available to, and understood
by, the laboratory personnel conducting the work.
14.2 HPLC System Performance
14.2.1 The general appearance of the HPLC chromatograph
should be similar to that shown in Figure 4.
14.2.2 The HPLC system efficiency and peak asymmetry
factor should be determined in the following manner.
A solution of the formaldehyde DNPH derivative cor-
responding to at least 20 times the detection
limit should be injected with the recorder chart
sensitivity and speed set to yield a peak
approximately 75% of full scale and 1 cm wide at
half height. The peak asymmetry factor is determined
as shown in Figure 5, and should be between
0.8 and 1.8.
-------
T05-14
14.2.3 HPLC system efficiency is calculated according to
the following equation:
N = 5.54
where
N = column efficiency, theoretical plates
tr= retention time of components (seconds)
W-j/2 = width of component peak at half height
(seconds)
A column efficiency of >5,000 should be obtained.
14.2.4 Precision of response for replicate HPLC injections
should be ± 10% or less, day to day, for calibration
standards. Precision of retention times should be
± 2%, on a given day.
14.3 Process Blanks
14.3.1 Prior to use a 10 ml aliquot of each batch of DNPH
reagent should be analyzed as described in Section
11. In general,formaldehyde levels equivalent to
>5 ng/L in a 60 liter sample should be achieved
and other aldehyde levels should be <1 ng/L.
14.3.2 At least one field blank should be shipped and
analyzed with each group of samples. The field
blank is treated identically to the samples except
that no air is drawn through the reagent. The
same performance criteria described in 14.3.1
should be met for process blanks.
-------
T05-15
14.4 Method Precision and Accuracy
14.4.1 Analysis of replicate samples indicates a pre-
cision of + 15-20% relative standard deviation
can be readily achieved. Each laboratory should
collect parallel samples periodically (at least one
for each batch of samples) to document their
precision in conducting the method.
14.4.2 Precision for replicate HPLC injections should
be + 10% or better, day to day, for calibration
standards.
14.4.3 Method accuracy is difficult to assess because of
the difficulty in generating accurate gaseous
standards. Literature results indicate (1-3)
recoveries of 75% or greater are achieved for a
broad range of aldehydes. Each laboratory should
periodically collect field samples wherein the
impinger solution is spiked with a known quantity
of the compound of interest, prepared as a dilute
methanol solution. Formaldehyde cannot be spiked
in this manner and therefore a solution of the DNPH
derivative should be used for spiking purposes.
14.4.4 Before initial use of the method each laboratory
should generate triplicate spiked samples at a minimum
of three concentration levels, bracketing the
range of interest for each compound. Triplicate
nonspiked samples must also be processed. Recover-
ies of >70 + 20% and blank levels of <5 ng/L for
formaldehyde and 1 ng/L for the other compounds
(assuming a 60 liter air sample) should be achieved.
-------
T05-16
References
(1) Grosjean, D., Fung, K., and Atkinson, R., "Measurements of
Aldehydes in the Air Environment", Proc. Air Poll. Cont.
Assoc., Paper 80-50.4, 1980.
(2) Grosjean, D. and Fung K., "Collection Efficiencies of Cartridges
and Micro-Impingers for Sampling of Aldehydes in Air as 2,4-
Dinitrophenylhydrazones", Anal. Chem. 54, 1221-1224, 1982.
(3) Grosjean, D., "Formaldehyde and Other Carbonyls in Los Angeles
Ambient Air", Environ. Sci. Techno!. J_6, 254-262, 1982.
(4) Riggin, R. M., "Technical Assistance Document for Sampling and
Analysis of Toxic Organic Compounds in Ambient Air", EPA-600/4-83-027.
U.S. Environmental Protection Agency, Research Triangle Park,
North Carolina, 1983.
(5) Annual Book of ASTM Standards, Part 11.03, "Atmospheric Analysis",
American Society for Testing and Material, Philadelphia,
Pennsylvania, 1983.
(6) Berry, D. A., Holdren, M. W., Lyon, T. F., Riggin, R. M., and
Spicer, C. W., "Turbine Engine Exhaust Hydrocarbon Analysis-Interim
Report on Task 1 and 2", Report on Contract No. F-08635-82-C-0131,
Air Force Engineering and Services Center, Tyndall AFB, Florida,
1983.
(7) Shiner, R., Fuson, R., and Curtin, D., "The Systematic Identification
of Organic Compounds", John Wiley and Sons, Inc., 5th ed. , New
York, 1964.
(8) "Method 6 Determination of SOg Emissions from Stationary Sources",
Federal Register, Vol. 42., No. 160, August 1977.
-------
T05-17
TABLE 1. ALDEHYDES AND KETONES FOR WHICH THE METHOD HAS BEEN EVALUATED
Compound
Formaldehyde
Acetaldehyde
Acrolein
Propanal
Acetone
Crotonaldehyde
Isobutyraldehyde
Methyl Ethyl Ketone
Benzaldehyde
Pentanal
o-Tolualdehyde
m-Tolualdehyde
p-Tolualdehyde
Hexanal
Molecular
Derivative
210
224
236
238
238
250
252
252
286
266
300
300
300
280
Weight
Compound
30
44
56
58
58
70
72
72
106
86
120
120
120
100
Typical
Relative
Retention
1.0
1.3
1.6
1.7
1.9(b)
2.3
2.4
2.8
3.2
3.7
4.8
5.1
5.3
5.7
(a) Using HPLC conditions shown in Figure 4.
Formaldehyde =1.0
(b) Acetone background levels in the reagent prevent its determination
in most cases.
-------
Silica Gel
Rotometer
Vent
Dry
Test
Meter
v
Needle
Valve
Pump
Sample Impinger -,
(DNPH Reagent) /
O
in
i
C»
FIGURE 1. TYPICAL SAMPLING SYSTEM
-------
T05-19
SAMPLING DATA SHEET
(One Sample Per Data Sheet)
PROJECT:
SITE:
DATE(S) SAMPLED:
LOCATION:
TIME PERIOD SAMPLED:,
OPERATOR:
INSTRUMENT MODEL NO:
PUMP SERIAL NO:
SAMPLING DATA
CALIBRATED BY:
Sample Number:
Start Time:
Stop Time:
Time
1.
2.
3.
4.
N.
Dry Gas
Meter
Reading
Rotameter
Reading
Flow
Rate,*Q
ml /Min
Ambient
Temperature
°C
Barometric
Pressure,
mmHg
Relative
Humidity, %
Comments
Total Volume Data**
Vm = (Final - Initial) Dry Gas Meter Reading, or
+ Q3---Q.N
1
Liters
Liters
N
1000 x (Sampling Time in Minutes)
* Flowrate from rotameter or soap bubble calibrator
(specify which).
** Use data from dry gas meter if available.
FIGURE 2. EXAMPLE SAMPLING DATA SHEET
-------
INJECTION
VALVE
COLUMN
MOBILE
PHASE
RESERVOIR
VARIABLE
WAVELENGTH
UV
DETECTOR
• •
DATA
SYSTEM
o
en
ro
o
•
I
STRIPCHART
RECORDER
FIGURE 3 TYPICAL HPLC SYSTEM
-------
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i r~r i
a
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i i i i
0 4
c
CD 0)
-So ^,
!>N ^- -£•
^ 0
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o +•* *"
"(O +-> O "^ <1)
C 0
o <.
•r— «
Q.
o
L-
Q-
i
(
I
i
Uv,
^o^o §
c . ^ c
| « 1 i
1 *° -c
1 +J o
c .-
, QJ 0
Q. >,
^ 1
III ;lv;! ]lv
1 I 1 I I 1 \ I I I I 1 ^ 1 I 1 ' 1 ' I ' 1 ' ! I 1 ! 1 1 | I ' T I J t 1 1 I '
0 60 80 10 0 c' 0 14 0 160 18 0 20 0
o
en
i
ro
FIGURE 4. TYPICAL HPLC CHROMATOGRAM
Column - Zorbax ODS, 250 x 4.6 mm
Mobile Phase - 80/20 Methanol/^O
Flow Rate - 1 rnL/Minuto
Detector - UV at 370 nm
-------
T05-22
Asymmetry Factor •
BC
AB
Exempt* Calculation:
Paak Height - OE - 100 mm
10% Paak Height - BD - 10 mm
Peak Width at 10% Peak Height - AC - 23 mm
AB "11 mm
BC * 12 mm
Therefore: Asymmetry Factor » — - 1.1
FIGURE 8. PEAK ASYMMETRY CALCULATION
-------
APPENDIX A—EPA METHOD 608
svEPA
United States
Environmental Protection
Agency
Environmental Monitoring and
Support Laboratory
Cincinnati OH 45268
Research and Development
Test Method
Organochlorine Pesticides
and PCBs — Method 608
1. Scope and Application
1.1 This method covers the
determination of certain organochlorine
pesticides and PCBs. The following
parameters can be determined by this
method:
Parameter
STORET No.
CAS No.
Aldrin
o-BHC
/J-BHC
d-BHC
y-BHC
Chlordane
4,4 '-ODD
4, 4 '-DDE
4,4 '-DDT
Dieldrin
Endosulfan I
Endosulfan II
Endosulfan sulfate
Endrin
Endrin aldehyde
Heptachlor
Heptachlor epoxide
Toxaphene
PCB-1016
PCB-1221
PCB-1232
PCB-1242
PCB-1248
PC B- 12 54
PCB-1260
39330
39337
39338
34259
39340
39350
39310
39320
39300
39380
34361
34356
34351
39390
34366
39410
39420
39400
34671
39488
39492
39496
39500
39504
39508
309-00-2
319-84-6
319-85-7
319-86-8
58-89-9
57-74-9
72-54-8
72-55-9
50-29-3
60-57-1
959-98-8
33212-65-9
1031-07-8
72-20-8
7421-93-4
76-44-8
1024-57-3
8001-35-2
12674-11-2
11104-28-2
11141-16-5
53469-21-9
12672-29-6
11097-69-1
11096-82-5
1.2 This is a gas chromatographic
(GO method applicable to the determi-
nation of the compounds listed above
in municipal and industrial discharges
as provided under 40 CFR 136.1.
When this method is used to analyze
unfamiliar samples for any or all of the
compounds above, compound identifi-
cations should be supported by at least
one additional qualitative technique.
This method describes analytical
conditions for a second gas
chromatographic column that can be
used to confirm measurements made
with the primary column. Method 625
provides gas chromatograph/mass
spectrometer (GC/MS) conditions
appropriate for the qualitative and
608-1
July 1982
-------
quantitative confirmation of results for
all of the parameters listed above,
using the extract produced by this
method
1.3 The method detection limit (MDL,
defined in Section 14.1 (in for each
parameter is listed in Table 1 . The MDL
for a specific wastewater may differ
from those listed, depending upon the
nature of interferences in the sample
matrix.
1.4 The sample extraction and
concentration steps in this method are
essentially the same as in methods
606, 609, 611 and 61 2. Thus, a
single sample may be extracted to
measure the parameters included in the
scope of each of these methods. When
cleanup is required, the concentration
levels must be high enough to permit
selection of aliquots as necessary to
apply appropriate cleanup procedures.
The analyst is allowed the latitude to
select gas chromatographic conditions
appropriate for the simultaneous
measurement of combinations of these
parameters.
1.5 Any modification of this method,
beyond those expressly permitted,
shall be considered as major
modifications subject to application
and approval of alternate test
procedures under 40 CFR 1 36.4 and
136.5.
1.6 This method is restricted to use
by or under the supervision of analysts
experienced in the use of gas chroma-
tography and in the interpretation of
gas chromatograms. Each analyst must
demonstrate the ability to generate
acceptable results with this method
using the procedure described in
Section 8.2.
2. Summary of Me'thod
2.1 A measured volume of sample,
approximately one-liter, is solvent
extracted with methylene chloride
using a separatory funnel. The
methylene chloride extract is dried and
exchanged to hexane, during
concentration to a final volume of 10
ml or less. Gas chromatographic
conditions are described which permit
the separation and measurement of the
parameters in the extract by electron
capture GC(2>.
2.2 The method provides a Flonsil
column procedure and elemental sulfur
removal procedure to aid in the
elimination of interferences that may
be encountered.
3. Interferences
3.1 Method interferences may be
caused by contaminants in solvents,
reagents, glassware, and other sample
processing hardware that lead to
discrete artifacts and/or elevated
baselines in gas chromatograms. All of
these materials must be routinely
demonstrated to be free from inter-
ferences under the conditions of the
analysis by running laboratory reagent
blanks as described in Section 8 5.
3.1.1 Glassware must be scrupulously
cleaned'31. Clean all glassware as soon
as possible after use by rinsing with the
last solvent used in it This should be
followed by detergent washing with
hot water, and rinses with tap water
and distilled water. It should then be
drained dry and heated in a muffle
furnace at 400 °C for 1 5 to 30
minutes Some thermally stable
materials, such as PCBs, may not be
eliminated by this treatment. Solvent
rinses with acetone and pesticide
quality hexane may be substituted for
the muffle furnace heating. Thorough
rinsing with such solvents usually
elmmates PCB interference. Volumetric
ware should not be heated in a muffle
furnace. After drying and cooling,
glassware should be sealed and stored
in a clean environment to prevent any
accumulation of dust or other
contaminants Store inverted or capped
with aluminum foil
3.1.2 The use of high purity reagents
and solvents helps to minimize
interference problems. Purification of
solvents by distillation in all-glass
systems may be required.
3.2 Interferences by phthalate esters
can pose a major problem in pesticide
analysis when using the elution capture
detector. These compounds generally
appear in the chromatogram as large
elutmg peaks, especially in the 1 5 and
50% fractions from Florisil. Common
flexible plastics contain varying
amounts of phthalates. These phtha-
lates are easily extracted or leached
from such materials during laboratory
operations. Cross contamination of
clean glassware routinely occurs when
plastics are handled during extraction
steps, especially when solvent wetted
surfaces are handled. Interferences
from phthalates can best be minimized
by avoiding the use of plastics in the
laboratory. Exhaustive cleanup of
reagents and glassware may be
required to eliminate background
phthalate contamination!4.5). The
interferences from phthalate esters can
be avoided by using a microcoulometric
or electrolytic conductivity detector.
3.3 Matrix interferences may be
caused by contaminants that are
coextracted from the sample The
extent of matrix interferences will vary
considerably from source to source,
depending upon the nature and
diversity of the industrial complex or
municipality being sampled. The
cleanup procedures in Section 1 1 can
be used to overcome many of these
interferences, but unique samples may
require additional cleanup approaches
to achieve the MDL listed in Table 1.
4. Safety
4.1 The toxicity or carcinogenicity of
each reagent used in this method has
not been precisely defined; however,
each chemical compound should be
treated as a potential health hazard.
From this viewpoint, exposure to these
chemicals must be reduced to the
lowest possible level by whatever
means available. The laboratory is
responsible for maintaining a current
awareness file of OSHA regulations
regarding the safe handling of the
chemicals specified in this method. A
reference file of material data handling
sheets should also be made available to
all personnel involved in the chemical
analysis. Additional references to
laboratory safety are available and
have been identified16'81 for the
information of the analyst.
4.2 The following parameters
covered by this method have been
tentatively classified as known or
suspected, human or mammalian
carcinogens: 4,4'-DDT,4,4'-DDD, the
BHCs, and the PCBs. Primary
standards of these toxic compounds
should be prepared in a hood.
5. Apparatus and Materials
5.1 Sampling equipment, for discrete
or composite sampling.
5.1.1 Grab sample bottle —Amber
glass, one-liter or one-quart volume,
fitted with screw caps lined with
Teflon. Foil may be substituted for
Teflon if the sample is not corrosive. If
amber bottles are not available, protect
samples from light. The container must
be washed, rinsed with acetone or
methylene chloride, and dried before
use to minimize contamination.
5.1.2 Automatic sampler (optional) —
Must incorporate glass sample
containers for the collection of a mini-
mum of 250 mL. Sample containers
must be kept refrigerated at 4 °C and
protected from light during compositing.
If the sampler uses a peristaltic pump,
a minimum length of compressible
608 2
July 1982
-------
silicons rubber tubing may be used.
Before use, however, the compressible
tubing should be thoroughly rinsed
with methanol, followed by repeated
rinsings with distilled water to minimize
the potential for contamination of the
sample. An integrating flow meter is
required to collect flow proportional
composites.
5.2 Glassware (All specifications are
suggested. Catalog numbers are
included for illustration only).
5.2.1 Separatory funnel- 2000-mL,
with Teflon stopcock.
5.2.2 Drying column —Chroma-
tographic column approximately 400
mm long x 1 9 mm ID, with coarse frit.
5.2.3 Chromatographic column —
Pyrex, 400 mm long x 22 mm ID,
with coarse fritted plate and Teflon
stopcock (Kontes K-42054 or
equivalent).
5.2.4 Concentrator tube, Kuderna-
Danish— 10-mL, graduated (Kontes K-
570050-1 025 or equivalent). Calibra-
tion must be checked at the volumes
employed in the test. Ground glass
stopper is used to prevent evaporation
of extracts.
5.2.5 Evaporative flask, Kuderna-
Danish- 500-mL (Kontes K-570001 -
0500 or equivalent). Attach to
concentrator tube with springs.
5.2.6 Snyder column, Kuderna-
Danish —three-ball macro (Kontes
K-503000-0121 or equivalent).
5.2.7 Vials-Amber glass, 10-to
1 5-ml capacity, with Teflon-lined
screw cap.
5.3 Boiling chips —approximately
10/40 mesh. Heat to 400 °C for 30
minutes or Soxhlet extract with
methylene chloride.
5.4 Water bath-Heated, with
concentric ring cover, capable of
temperature control ( ± 2 °C). The bath
should be used in a hood.
5.5 Balance —Analytical, capable of
accurately weighing 0.0001 g.
5.6 Gas chromatograph — An
analytical system complete with gas
chromatograph suitable for on-column
injection and all required accessories
including syringes, analytical columns,
gases, detector, and strip-chart
recorder. A data system is
recommended for measuring peak
areas.
5.5.1 Column 1 — 1.8 m long x 4
mm ID glass, packed with 1.5%
SP-2250/1.95% SP-2401 on
Supelcoport (100/1 20 mesh) or
equivalent. Column 1 was used to
develop the method performance
statements in Section 14. Guidelines
for the use of alternate column
packings are provided in Section 12.1.
5.6.2 Column 2-1 .8 m long x 4
mm ID glass, packed with 3% OV-1 on
Supelcoport (100/120 meshl or
equivalent.
5.6.3 Detector—Electron capture.
This detector has proven effective in
the analysis of wastewaters for the
parameters listed in the scope, and
was used to develop the method
performance statements in Section 14.
Guidelines for the use of alternate
detectors are provided in Section 12.1.
6. Reagents
6.1 Reagent water —Reagent water is
defined as a water in which an mter-
ferent is not observed atthe MDL of
each parameter of interest.
6.2 Sodium hydroxide solution (1 0
N)-(ACS). Dissolve 40g NaOH in
reagent water and dilute to 1 00 ml.
6.3 Sodium thiosulfate-(ACS).
Granular
6.4 Sulfuric acid solution (1 + 1 ) —
(ACS). Slowly, add 50 mL H2S04 (sp.
gr. 1.84) to 50 mL of reagent water.
6.5 Acetone, hexane, isooctane
(2,2,4-trimethylpentane), methylene
chloride —Pesticide quality or
equivalent.
6.6 Ethyl ether—Pesticide quality or
equivalent, redistilled in glass if
necessary.
5.5.1 Must be free of peroxides as
indicated by EM Laboratories Quant
test strips (Available from Scientific
Products Co., Cat. No. P1 1 26-8, and
others suppliers.)
6.6.2 Procedures recommended for
removal of peroxides are provided with
the test strips. After cleanup, 20 mL
ethyl alcohol preservative must be
added to each liter of ether.
6.7 Sodium sulfate—(ACS) Granular,
anhydrous. Purify by heating at 400 °C
for 4 hours in a shallow tray.
6.8 Florisil-PR grade (60/100
mesh); purchase activated at 1 250 °F
and store in dark in glass containers
with glass stoppers or foil-lined screw
caps. Before use, activate each batch
at least 1 6 hours at 1 30 °C in a foil
covered glass container.
6.9 Mercury —Triple distilled.
6.10 Copper powder—Activated.
6.11 Stock standard solutions (1.00
^g/^D — Stock standard solutions can
be prepared from pure standard
materials or purchased as certified
solutions.
6.11.1 Prepare stock standard
solutions by accurately weighing about
0.01 00 grams of pure material
Dissolve the material in isooctane,
dilute to volume in a 1 0-mL volumetric
flask. Larger volumes can be used at
the convenience of the analyst. If
compound purity is certified at 96% or
greater, the weight can be used
without correction to calculate the
concentration of the stock standard.
Commercially prepared stock standards
can be used at any concentration if
they are certified by the manufacturer
or by an independent source.
6.11.2 Transfer the stock standard
solutions into Teflon-sealed screw-cap
bottles Store at 4 °C and protect from
light. Stock standard solutions should
be checked frequently for signs of
degradation or evaporation, especially
just prior to preparing calibration
standards from them. Quality control
check standards that can be used to
determine the accuracy of calibration
standards will be available from the
U.S. Environmental Protection Agency,
Environmental Monitoring and Support
Laboratory, Cincinnati, Ohio 45268.
6.11.3 Stock standard solutions
must be replaced after six months, or
sooner if comparison with check
standards indicate a problem.
7. Calibration
7.1 Establish gas Chromatographic
operating parameters which produce
retention times equivalent to those
indicated in Table 1. The gas
Chromatographic system may be
calibrated using the external standard
technique (Section 7.2) or the internal
standard technique (Section 7.3).
7.2 External standard calibration
procedure;
7.2.1 Prepare calibration standards
at a minimum of three concentration
levels for each parameter of interest by
adding volumes of one or more stock
standards to a volumetric flask and
diluting to volume with isooctane. One
of the external standards should be at a
concentration near, but above, the
MDL and the other concentrations
should correspond to the expected
range of concentrations found in real
samples or should define the working
range of the detector.
608-3
July 1982
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7.2.2 Using injections of 2 to 5 ^L of
each calibration standard, tabulate
peak height or area responses against
the mass injected. The results can be
used to prepare a calibration curve for
each compound. Alternatively, if the
ratio of response to amount injected
(calibration factor) is a constant over
the working range K10% relative
standard deviation, RSD), linearity
through the origin can be assumed and
the average ratio or calibration factor
can be used in place of a calibration
curve.
7.2.3 The working calibration curve
or calibration factor must be verified on
each working day by the measurement
of one or more calibration standards. If
the response for any parameter varies
from the predicted response by more
than ±10%, the test must be repeated
using a fresh calibration standard.
Alternatively, a new calibration curve
or calibration factor must be prepared
for that compound.
7.3 Internal standard calibration
procedure. To use this approach, the
analyst must select one or more
internal standards that are similar in
analytical behavior to the compounds
of interest. The analyst must further
demonstrate that the measurement of
the internal standard is not affected by
method or matrix interferences.
Because of these limitations, no
internal standard can be suggested that
is applicable to all samples.
7.3.1 Prepare calibration standards
at a minimum of three concentration
levels for each parameter of interest by
adding volumes of one or more stock
standards to a volumetric flask. To
each calibration standard, add a known
constant amount of one or more
internal standards, and dilute to volume
with isooctane. One of the standards
should be at a concentration near, but
above, the MDL and the other concen-
trations should correspond to the
expected range of concentrations
found in real samples or should define
the working range of the detector.
7.3.2 Using injections of 2 to 5 ^L of
each calibration standard, tabulate
peak height or area responses against
concentration for each compound and
internal standard, and calculate
response factors (RF) for each
compound using equation 1.
Eq. 1. RF = (ASC,S)/(AISCS)
where:
As = Response for the parameter to
be measured.
A1S = Response for the internal
standard.
Cls = Concentration of the internal
standard, (^ig/L).
Cs = Concentration of the param-
eter to be measured, (j/g/L).
If the RF value over the working
range is a constant «1 0% RSD), the
RF can be assumed to be invariant and
the average RF can be used for
calculations. Alternatively, the results
can be used to plot a calibration curve
of response ratios, AS/A1S, vs. RF.
7.3.3 The working calibration curve
or RF must be verified on each working
day by the measurement of one or
more calibration standards. If the
response for any parameter varies from
the predicted response by more than
± 1 0%, the test must be repeated
using a fresh calibration standard.
Alternatively, a new calibration curve
must be prepared for that compound.
7.4 The cleanup procedure in Section
11 utilizes Flonsil chromatography.
Florisil from different batches or
sources may vary in absorptive
capacity. To standardize the amount of
Florisil which is used, the use of lauric
acid value'91 is suggested. The refer-
enced procedure determines the
adsorption from hexane solution of
lauric acid (mg) per gram Florisil. The
amount of Florisil to be used for each
column is calculated by dividing this
factor into 110 and multiplying by 20
g.
7.5 Before using any cleanup
procedure, the analyst must process a
series of calibration standards through
the procedure to validate elution
patterns and the absence of interfer-
ences from the reagents.
8. Quality Control
8.1 Each laboratory that uses this
method is required to operate a formal
quality control program. The minimum
requirements of this program consist of
an initial demonstration of laboratory
capability and the analysis of spiked
samples as a continuing check on
performance. The laboratory is required
to maintain performance records to
define the quality of data that is
generated. Ongoing performance
checks must be compared with
established performance criteria to
determine if the results of analyses are
within accuracy and precision limits
expected of the method.
8.1.1 Before performing any analyses,
the analyst must demonstrate the
ability to generate acceptable accuracy
and precision with this method. This
ability \s established as described in
Section 8.2.
8.1.2 In recognition of the rapid
advances that are occurring in chroma-
tography, the analyst is permitted
certain options to improve the separa-
tions or lower the cost of measurements.
Each time such modifications are made
to the method, the analyst is required
to repeat the procedure in Section 8 2.
8.1.3 The laboratory must spike and
analyze a minimum of 1 0% of all
samples to monitor continuing labora-
tory performance. This procedure is
described in Section 8.4.
8.2 To establish the ability to
generate acceptable accuracy and pre-
cision, the analyst must perform the
following operations.
8.2.1 Select a representative spike
concentration for each compound to be
measured. Using stock standards,
prepare a quality control check sample
concentrate m acetone 1 000 times
more concentrated than the selected
concentrations. Quality control check
sample concentrates, appropriate for
use with this method, will be available
from the U.S. Environmental Protection
Agency, Environmental Monitoring and
Support Laboratory, Cincinnati, Ohio
45268.
5.2.2 Using a pipet, add 1.00 mL of
the check sample concentrate to each
of a minimum of four 1000-mL aliquots
of reagent water. A representative
wastewater may be used in place of
the reagent water, but one or more
additional aliquots must be analyzed to
determine background levels, and the
spike level must exceed twice the
background level for the test to be
valid. Analyze the aliquots according to
the method beginning in Section 1 0.
8.2.3 Calculate the average percent
recovery, (R), and the standard devia-
tion of the percent recovery (s), for the
results. Wastewater background cor-
rections must be made before R and s
calculations are performed.
8.2.4 Using Table 2, note the
average recovery (X) and standard
deviation (p) expected for each method
parameter. Compare these to the cal-
culated values for R and s. If s > 2p or
|X-R| > 2p, review potential problem
areas and repeat the test.
5.2.5 The U.S. Environmental Pro-
tection Agency plans to establish
performance criteria for R and s based
upon the results of interlaboratory
testing. When they become available,
these criteria must be met before any
samples may be analyzed.
8.3 The analyst must calculate
method performance criteria and define
608-4
July 1982
-------
the performance of the laboratory for
each spike concentration and
parameter being measured.
8.3.1 Calculate upper and lower
control limits for method performance:
Upper Control Limit (UCU = R + 3s
Lower Control Limit (LCD = R - 3s
where R and s are calculated as in
Section 8.2.3. The UCL and LCL can
be used to construct control charts110'
that are useful in observing trends in
performance. The control limits above
be replaced by method performance
criteria as they become available from
the U.S. Environmental Protection
Agency.
8.3.2 The laboratory must develop
and maintain separate accuracy
statements of laboratory performance
for wastewater samples. An accuracy
statement for the method is defined as
R ± s. The accuracy statement should
be developed by the analysis of four
aliquots of wastewater as described in
Section 8.2.2, followed by the calcula-
tion of R and s. Alternately, the analyst
may use four wastewater data points
gathered through the requirement for
continuing quality control in Section
8.4. The accuracy statements should
be updated regularly! 10>.
8.4. The laboratory is required to
collect a portion of their samples in
duplicate to monitor spike recoveries.
The frequency of spiked sample analysis
must be at least 10% of all samples or
one sample per month, whichever is
greater. One aliquot of the sample must
be spiked and analyzed as described in
Section 8.2. If the recovery for a
particular parameter does not fall
within the control limits for method
performance, the results reported for
that parameter in all samples processed
as part of the same set must be quali-
fied as described in Section 13.5. The
laboratory should monitor the frequency
of data so qualified to ensure that it
remains at or below 5%.
8.5 Before processing any samples,
the analyst should demonstrate through
the analysis of a one-liter aliquot of
reagent water, that all glassware and
reagent interferences are under control.
Each time a set of samples is extracted
or there is a change in reagents, a
laboratory reagent blank should be
processed as a safeguard against
laboratory contamination.
8.6 It is recommended that the
laboratory adopt additional quality
assurance practices for use with this
method. The specific practices that are
most productive depend upon the
needs of the laboratory and the nature
of the samples. Field duplicates may be
analyzed to monitor the precision of
the sampling technique. When doubt
exists over the identification of a peak
on the chromatogram, confirmatory
techniques such as gas chromatography
with a dissimilar column, specific
element detector, or mass spectrometer
must be used. Whenever possible, the
laboratory should perform analysis of
standard reference materials and parti-
cipate in relevant performance
evaluation studies.
9. Sample Collection,
Preservation, and Handling
9.1 Grab samples must be collected
in glass containers. Conventional
sampling practices'11 > should be
followed, except that the bottle must
not be prewashed with sample before
collection. Composite samples should
be collected in refrigerated glass
containers in accordance with the
requirements of the program. Automatic
sampling equipment must be as free as
possible of Tygon tubing and other
potential sources of contamination.
9.2 The samples must be iced or
refrigerated at 4 °C from the time of
collection until extraction. If the
samples will not be extracted within
72 hours of collection, the sample
should be adjusted to a pH range of
5.0 to 9.0 with sodium hydroxide or
sulfuric acid. Record the volume of acid
or base used. If aldrin is to be
determined, add sodium thiosulfate
when residual chlorine is present. U.S.
Environmental Protection Agency
methods 330.4 and 330.5 may be
used to measure chlorine residual112'.
Field test kits are available for this
purpose.
9.3 All samples must be extracted
within 7 days and completely analyzed
within 40 days of extraction'2'.
10. Sample Extraction
10.1 Mark the water meniscus on the
side of the sample bottle for later deter-
mination of sample volume. Pour the
entire sample into a two-liter separatory
funnel.
10.2 Add 60 mL methylene chloride
to the sample bottle, seal, and shake
30 seconds to rinse the inner surface.
Transfer the solvent to the separatory
funnel and extract the sample by
shaking the funnel for two minutes
with periodic venting to release excess
pressure. Allow the organic layer to
separate from the water phase for a
minimum of 10 minutes. If the emulsion
interface between layers is more than
one-third the volume of the solvent
layer, the analyst must employ me-
chanical techniques to complete the
phase separation. The optimum tech-
nique depends upon the sample, but
may include stirring, filtration of the
emulsion through glass wool, centrifu-
gation, or other physical methods.
Collect the methylene chloride extract
in a 250-mL Erlenmeyer flask,
10.3 Add a second 60-mL volume of
methylene chloride to the sample bottle
and repeat the extraction procedure a
second time, combining the extracts in
the Erlenmeyer flask. Perform a third
extraction in the same manner.
10.4 Assemble a Kuderna-Danish
(K-D) concentrator by attaching a
10-mL concentrator tube to a 500-mL
evaporative flask. Other concentration
devices or techniques may be used in
place of the Kuderna Danish if the
requirements of Section 8.2 are met.
10.5 Pour the combined extract
through a drying column containing
about 1 0 cm of anhydrous sodium
sulfate, and collect the extract in the
K-D concentrator. Rinse the Erlenmeyer
flask and column with 20 to 30 mL of
methylene chloride to complete the
quantitative transfer.
10.6 Add one or two clean boiling
chips to the evaporative flask and
attach a three-ball Snyder column.
Prewet the Snyder column by adding
about 1 mL methylene chloride to the
top. Place the K-D apparatus on a hot
water bath (60 to 65 °C) so that the
concentrator tube is partially immersed
in the hot water and the entire lower
rounded surface of the flask is bathed
with hot vapor. Adjust the vertical
position of the apparatus and the water
temperature as required to complete
the concentration in 1 5 to 20 minutes.
At the proper rate of distillation the
balJs of the column will actively chatter
but the chambers will not flood with
condensed solvent. When the apparent
volume of liquid reaches 1 mL, remove
the K-D apparatus and allow it to dram
and cool for at least 1 0 minutes.
10.7 Increase the temperature of the
hot water bath to about 80 °C.
Momentarily remove the Snyder
column, add 50 mL of hexane and a
new boiling chip and reattach the
Snyder column. Prewet the column by
adding about 1 mL of hexane to the
top. Concentrate the solvent extract as
before. The elapsed time of concentra-
tion should be 5 to 10 minutes. When
the apparent volume of liquid reaches 1
mL, remove the K-D apparatus and
allow it to drain and cool at least 10
minutes.
608-5
July 1982
-------
10.8 Remove the Snyder column and
rinse the flask and its lower joint into
the concentrator tube with 1 to 2 mL
of hexane. A 5-mL syringe is recom-
mended for this operation. Stopper the
concentrator tube and store
refrigerated if further processing will
not be performed immediately. If the
extracts will be stored longer than two
days, they should be transferred to
Teflon-sealed screw-cap bottles. If the
sample extract requires no further
cleanup, proceed with gas chromato-
graphic analysis. If the sample requires
cleanup proceed to Section 1 1.
10.9 Determine the original sample
volume by refilling the sample bottle to
the mark and transferring the liquid to a
1 000-mL graduated cylinder. Record
the sample volume to the nearest 5 mL.
11. Cleanup and Separation
11.1 Cleanup procedures may not be
necessary for a relatively clean sample
matrix. The cleanup procedures recom-
mended in this method have been used
for the analysis of various clean waters
and industrial effluents. If particular
circumstances demand the use of an
alternative cleanup procedure, the
analyst must determine the elution
profile and demonstrate that the
recovery of each compound of interest
is no less than 85%. The Flonsil
column allows for a select fractionation
of the compounds and will eliminate
polar materials. Elemental sulfur
interferes with the electron capture gas
chromatography of certain pesticides,
but can be removed by the techniques
described below.
11.2 Florisil column cleanup:
11.2.1 Add a weight of Florisil
(nominally 21 g) predetermined by cali-
bration (Section 7.4 and 7.5), to a
chromatographic column. Settle the
Florisil by tapping the column. Add
sodium sulfate to the top of the Florisil
to form a layer 1 to 2 cm deep. Add 60
mL of hexane to wet and rinse the
sodium sulfate and Florisil. Just prior to
exposure of the sodium sulfate to air,
stop the elution of the hexane by
closing the stopcock on the chroma-
tography column. Discard the eluate.
11.2.2 Adjust the sample extract
volume to 10 mL with hexane and
transfer it from the K-D concentrator
tube to the Florisil column. Rinse the
tube twice with 1 to 2 mL hexane,
adding each rinse to the column.
11.2.3 Place a 500-mL K-D flask and
clean concentrator tube under the
chromatography column. Drain the
column into the flask until the sodium
sulfate latyer is nearly exposed. Elute
the column with 200 mL of 6% ethyl
ether in hexane (V/V) (Fraction 1) using
a drip rate of about 5 mL/min. Remove
the K-D flask and set aside for later
concentration. Elute the column again,
using 200 mL of 1 5% ethyl ether in
hexane (V/V)(Fraction 2), into a second
K-D flask. Perform the third elution
using 200 mL of 50% ethyl ether in
hexane (V/V)(Fraction 3). The elution
patterns for the pesticides an PCB's are
shown in Table 2.
11.2.4 Concentrate the eluates by
standard K-D techniques (Section
10.6), substituting hexane for the
glassware rinses and using the water
bath at about 85 °C. Adjust final
volume to 1 0 mL with hexane. Analyze
by gas chromatography.
11.3 Elemental sulfur will usually
elute entirely in Fraction 1 of the Florisil
column cleanup. To remove sulfur
interference from this fraction or the
original extract, pipet 1.00 mL of the
concentrated extract into a clean con-
centrator tube or Teflon-sealed vial.
Add one to three drops of mercury and
seal'13), Agitate the contents of the
vial for 1 5 to 30 seconds. Prolonged
shaking (two hours) may be required. If
so, this may be accomplished with a
reciprocal shaker. Alternatively,
activated copper powder may be used
for sulfur removal'141. Analyze by gas
chromatography.
12. Gas Chromatography
12.1 Table 1 summarizes the
recommended operating conditions for
the gas chromatograph. This table
includes retention times and MDL that
were obtained under these conditions.
Examples of the parameter separations
achieved by column 1 are shown in
Figures 1 to 10. Other packed
columns, chromatographic conditions,
or detectors may be used if the
requirements of Section 8.2 are met.
Capillary (open-tubular) columns may
also be used if the relative standard
deviations of responses for replicate
injections are demonstrated to be less
than 6% and the requirements of
Section 8.2 are met.
12.2 Calibrate the system daily as
described in Section 7.
12.3 If the internal standard
approach is being used, the internal
standard must be added to the sample
extract and mixed thoroughly
immediately, before injection into the
instrument.
12.4 Inject 2 to 5/A of the sample
extract using the solvent-flush
technique* 15>. Smaller (1 .0 nD volumes
can be injected if automatic devices are
employed. Record the volume injected
to the nearest 0.05 ^L, the total
extract volume, and the resulting peak
size in area or peak height units.
12.5 The width of the retention time
window used to make identifications
should be based upon measurements
of actual retention time variations of
standards over the course of a day.
Three times the standard deviation of a
retention time for a compound can be
used to calculate a suggested window
size; however, the experience of the
analyst should weigh heavily in the
interpretation of chromatograms.
12.6 If the response for the peak
exceeds the working range of the
system, dilute the extract and
reanalyze.
12.7 If the measurement of the peak
response is prevented by the presence
of interferences, further cleanup is
required.
13. Calculations
13.1 Determine the concentration of
individual compounds in the sample.
13. 1. 1 If the external standard
calibration procedure is used, calculate
the amount of material injected from
the peak response using the calibration
curve or calibration factor in Section
7.2.2. The concentration in the sample
can be calculated from equation 2:
Eq. 2. Concentration,
(A)(Vt)
(V)(V >
where:
A = Amount of material injected, in
nanograms.
V, = Volume of extract injected
V
Volume of total extract i
Vs = Volume of water extracted
(mL).
13.1.2 If the internal standard cali-
bration procedure was used, calculate
the concentration in the sample using
the response factor (RF) determined in
Section 7.3.2 and equation 3.
Eq. 3
(A.MI,)
Concentration, Mg/L= (AIS)(RF)(VO)
where:
As = Response for the parameter to
be measured.
A1S = Response for the internal
standard.
ls = Amount of internal standard
added to each extract (fig).
Volum
liters.
V0 = Volume of water extracted, in
608-6
July 1982
-------
13.2 When it is apparent that two or
more PCS (Aroclor) mixtures are
present, the Webb and McCall
procedure'16> may be used to identify
and quantify the Aroclors.
13.3 For multicomponent mixtures
(chlordane, toxaphene and PCBs)
match retention times of peaks in the
standards with peaks in the sample.
Quantitate every identifiable peak
unless interference with individual
peaks persist after cleanup. Add peak
height or peak area of each identified
peak in the chromatogram. Calculate
as total response in the sample versus
total response in the standard.
13.4 Report results in micrograms
per liter without correction for recovery
data. When duplicate and spiked
samples are analyzed, report all data
obtained with the sample results.
13.5 For samples processed as part
of a set where the laboratory spiked
sample recovery falls outside of the
control limits in Section 8.3, data for
the affected parameters must be
labeled as suspect.
14. Method Performance
14.1 The method detection limit
(MDL) is defined as the minimum
concentration of a substance that can
be measured and reported with 99%
confidence that the value is above
zero'1'. The MDL concentration^ listed
in Table 1 were obtained using reagent
water' 17>. Similar results were achieved
using representative wastewaters.
14.2 This method has been tested
for linearity of spike recovery from
reagent water and has been demon-
strated to be applicable over the
concentration range from 4 x MDL up
to 1000 x MDL with the following
exceptions: Chlordane recovery at 4 x
MDL was low (60%); Toxaphene
recovery was demonstrated linear over
the range of 10 x MDL to 1000 x
MDLH7I.
14.3 In a single laboratory (South-
west Research Institute), using spiked
wastewater samples, the average
recoveries presented in Table 3 were
obtained<4>.-Each spiked sample was
analyzed in triplicate on two separate
days. The standard deviation of the
percent recovery is also included in
Table 3.
14.4 The U.S. Environmental Protec-
tion Agency is in the process of
conducting an interlaboratory method
study to fully define the performance
of this method.
References
1 See Appendix A
2. "Determination of Pesticides and
PCBs in Industrial and Municipal
Wastewaters." Report for EPA
Contract 68-03-2606 In preparation.
3. ASTM Annual Book of Standards,
Part 31, D3694, "Standard Practice
for Preparation of Sample Containers
and for Preservation," American
Society for Testing and Materials,
Philadelphia, PA, p. 678, 1980
4. Giam, D.S., Chan H S. and Nef,
G.S., "Sensitive Method for
Determination of Phthalate Ester
Plasticizers in Open-Ocean Biota
Samples," Ans/ytica/ Chemistry, 47,
2225, (1975).
5. Giam, C.S., Chan, H.S , "Control of
Blanks in the Analysis of Phthslates in
Air and Ocean Biota Samples," U.S.
National Bureau of Standards. Special
Publication 442, pp 701 708,1976.
6. "Carcinogens—Working With
Carcinogens," Department of Health,
Education, and Welfare, Public Health
Service. Center for Disease Control,
National Institute for Occupational
Safety1 and Health, Publication No.
77-206, Aug. 19/7
7. "OSHA Safety and Health
Standards, General Industry," (29 CFR
19101, Occupational Safety and
Health Administration, OSHA 2206,
(Revised, January 1976).
8. "Safety in Academic Chemistry
Laboratories," American Chemical
Society Publication, Committee on
Chemical Safety, 3rd Edition, 1 979.
9. Mills, P.A., "Variation of Flonsil
Activity: Simple Method for Measuring
Absorbent Capacity and Its Use in
Standardizing Florisil Columns,"
Journal of the Association of Official
Analytical Chemists, 51, 29 (1968).
10. "Handbook for AnalyticafQuality
Control in Water and Wastewatei
Laboratories," EPA-600/4-79-019,
U.S. Environmental Protection Agency,
Environmental Monitoring and Support
Laboratory, Cincinnati, Ohio 45268,
March 1979.
11. ASTM Annual Book of Standards,
Part 31, D3370, "Standard Practice
for Sampling Water," American
Society for Testing and Materials,
Philadelphia, PA. p. 76, 1980.
1 2. "Methods 330.4 (Titrimetric,
DPD-FAS) and 330 5 (Spectrophoto-
metnc, DPD) for Chlorine, Total
Residual," Methods for Chemical
Analysis of Water and Wastes, EPA
600-4/79-020, U S Environmental
Protection Agency, Environmental
Monitoring and Suppoit Laboratory,
Cincinnati, Ohio 45268, March 1979.
1 3. Goerlitz, D.F. and Law, L.M.,
Bulletin for Environmental
Contamination and Toxicology, 6 9
(1971).
1 4. "Manual of Analytical Methods for
the Analysis of Pesticides in Human
Environmental Samples," U.S. Environ-
mental Protection Agency, Health
Effects Research Laboratory, Research
Triangle Park, N.C., EPA Report
600/8-80-038, Section 1 1,B, p.6.
1 5 Burke, J.A., "Gas Chromatography
for Pesticide Residue Analysis; Some
Practical Aspects," Journal of the
Association of Official Analytical
Chemists, 48, 1037 (1965).
16. Webb, R.G., and McCall, A.C.,
"Quantitative PCB Standards for
Electron Capture Gas
Chromatography," Journal of
Chromatographtc Science, 11, 366
(1973)
1 7. "Method Detection Limit and
Analytical Curve Studies, EPA Methods
606, 607, and 608," Special letter
report for EPA Contract 68-03-2606.
Environmental Monitoring and Support
Laboratory —Cincinnati, Ohio 45268.
608-7
July 1982
-------
Table 1. Chromatographic Conditions and Method
Detection Limits
Retention Time Method
Table 2. Distribution of Chlorinated Pesticides and PCBs
into Florisil Column Fractions2
Percent Recovery
(min.) Detection Limit
Parameter
a-BHC
Y-BHC
P-BHC
Heptachlor
6-BHC
A Id r in
Hepachlor epoxide
Endosulfan 1
4, 4 '-DDE
Dieldrin
Endrin
4,4'-DDD
Endosulfan II
4, 4 '-DDT
Endrin aldehyde
Endosulfan sulfate
Chlordane
Toxaphene
PCB-1016
PCB-1221
PCB-1232
PCB-1242
PCB-1248
PCB-1254
PCB-1260
Column 1 conditions:
Column 1
1.35
.70
1.90
2.00
2.15
2.40
3.50
4.50
5.13
5.45
6.55
7.83
8.00
9.40
11.82
14.22
mr
mr
mr
mr
mr
mr
mr
mr
mr
Column 2
1.82
2.13
1.97
3.35
2.20
4.10
5.00
6.20
7.15
7.23
8.10
9.08
8.28
11.75
9.30
10.70
mr
mr
mr
mr
mr
mr
mr
mr
mr
W/L
0.003
0.004
0.006
0.003
0.009
0.004
0.083
0.014
0.004
0.002
0.006
0.011
0.004
0.012
0.023
0.066
0.014
0.24
nd
nd
nd
0.065
nd
nd
nd
Suoelcooort 1 1 00/1 20 mesh) coated
Parameter
Aldrin
a-BHC
P-BHC
6-BHC
y-BHC
Chlordane
4, 4 '-ODD
4, 4 '-DDE
4,4 '-DDT
Dieldrin
Endosulfan 1
Endosulfan
Endosulfan sulfate
Endrin
Endrin aldehyde
Heptachlor
Heptachlor epoxide
Toxaphene
PCB-1016
PCB-1221
PCB-1232
PCB-1242
PCB-1248
PCB-1254
PCB-1260
Fraction
1
100
100
97
98
100
100
99
98
100
0
37
0
0
4
0
100
WO
96
97
97
95
97
103
90
95
by Fraction
Fraction Fraction
2 3
WO
64
7 91
0 106
96
68 26
4
with 1.5%SP-2250/1.95%SP-2401 packedina 1.8m
long x 4 mm ID glass column with 5% Methane/95%
Argon carrier gas at a flow rate of 60 mL/min. Column
temperature isothermal at 200 °C, except for PCB-1016
through PCB-1248, which should be measured at
160°C.
Column 2 conditions: Supe/coport (100/120 mesh) coated
with 3% OV-1 in a 1.8 m long x 4 mm ID glass column
with 5% Methane/95% Argon carrier gas at a flow rate of
60 mL/min. Column temperature, isothermal at 200 °C,
for the pesticides; 140°C for PCB-1221 and 1232;
170°C for PCB-1016 and 1242 to 1268.
mr — Multiple peak response. See Figures 2 thru 10.
nd — Not determined.
Eluant composition by fraction:
Fraction 1 — 6% ethyl ether in hexane
Fraction 2— 15% ethyl ether in hexane
Fraction 3—50% ethyl ether in hexane
608-8
July 1982
-------
Table 3. Single Operator Accuracy and Precision
Average Standard Spike Number
Percent Deviation Range of Matrix
Parameter Recovery % (\tg/U Analyses Types
Aldrm 89
a-BHC 89
P-BHC 88
6-BHC 86
y-BHC 97
Chlorane 93
4-4' -ODD 92
4, 4 '-DDE 89
4, 4 '-DDT 92
Dieldrin 95
Endosu/fan I 96
Endosulfan II 97
Endosu/fan su/fate 99
Endrin 95
En drm aldeh yde 87
Heptachlor 88
Heptachlor epoxide 93
Toxaphene 95
PCB-1016 94
PCB-1221 96
PCB-1232 88
PCB-1242 92
PCB-1248 90
PCB-1254 92
PCB-1260 91
Column: 1.5%SP-2250+
2.5 2.0 15 3
2.0 1.0 15 3
1.3 2.0 15 3
3.4 2.0 15 3
3.3 1.0 15 3
4.1 20 21 4
1.9 6.0 15 3
2.2 3.0 15 3
3.2 8.0 15 3
2.8 3.0 15 2
2.9 3.0 12 2
2.4 5.0 14 3
4. 115 153
2.1 5.0 12 2
2.1 12 11 2
3.3 1.0 12 2
1.4 2.0 15 3
3.8 200 18 3
1.8 25 12 2
4.2 55-11O 12 2
2.4 110 12 2
2.0 28-56 12 2
1.6 40 12 2
Column: 1.5%SP-2250+
1.95% SP-2401 on
Supelcoport
Temperature: 200°C.
Detector: Electron capture
,
/
I ,
I / VW/^ *•
", J y v s — - — ~^^-~__
ty
• i i i i i i i
3.3 40 18 3 0 4 8 12 16
5-5 80 18 3 Retention time minutes
Figure 2. Gas chromatogram
1.95% SP-2401 on Supelcoport ot *™°r°*n*
I
Temperature: 200° C.
Detector: Electron capture
!t o
"* §•
fa0
2l -2 Q K.
^o 5 u. Q Q
v--v
S
^w
g
c
£
I
ill!
4 8 12
Retention time, minutes
Figure 1. Gas chromatogram of pesticides.
608-9
July 1982
-------
Column: 1.5% SP-2250+
1.95% SP-2401 on
Supelcoport
Temperature: 200°C.
Detector: Electron capture
2 6 10 14 18 22
Retention time, minutes
Figure 3. Gas chromatogram of toxaphene
Column: 1.5% SP-2250+ 1.95% SP-2401 on
Supelcoport
Temperature: 160°C.
Detector: Electron capture
26
2 6 10 14 18
Retention time, minutes
Figure 4. Gas chromatogram of PCB-1016.
608-10
22
Column: 1.5% SP-2250+ 1.95% SP-2401 on
Supelcoport
Temperature: 160°C.
Detector: Electron capture
2 6 10 14 18
Retention time, minutes
Figure 6. Gas chromatogram of PCB-1221.
Column: 1.5% SP-2250+ 1.95% SP-2401 on
Supelcoport
Temperature: 160°C.
Detector: Electron capture
22
2 6 10 14 18
Retention time, minutes
Figure 6. Gas chromatogram of PCB-1232.
July 1982
22
24
-------
Column: 1.5% SP-2250+ 1.95% SP-2401 on
Supelcoport
Temperature: 160°C.
Detector: Electron capture
2 6 10 14 18
Retention time, minutes
Figure 7. Gas chromatogram of PCB-1242.
22
Column: 1.5%SP-2250+ 1.95% SP-2401 on
Supelcoport
Temperature: 200°C.
Detector: Electron capture
2 6 10 14
Retention time, minutes
Figure 9. Gas chromatogram of PCB-1254.
18
22
Column: 1.5% SP-2250+ 1.95% SP-2401 on
Supelcoport
Temperature: 160°C.
Detector: Electron capture
2 6 10 14 18 22
Retention time, minutes
Figure 8. Gas chromatcgram of PCB-1248.
608-11
26
Column: 1.5% SP-2250+ 1.95% SP-2401 on
Supelcoport
Temperature: 200°C.
Detector: Electron capture
2 6 10 14 18 22
Retention time, minutes
Figure 10. Gas chromatogram of PCB-1260.
26
July 1982
' U S GOVERNMENT PRINTING OFFICE 1984 759-102/0944
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