EPA-600/2-77-202
October 1977
Environmental Protection Technology Series
MEASUREMENT OF POLYCYCLIC ORGANIC
IATERIALS AND OTHER HAZARDOUS ORGANIC
COMPOUNDS IN STACK GASES
State of the Art
Environmental Sciences Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Research Triangle Park, North Carolina 27711
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Projection Agency, have been grouped into nine series. These nine broad cate-
gor es were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This report has been assigned to the ENVIRONMENTAL PROTECTION TECH-
NOLOGY series. This series describes research performed to develop and dem-
onstrate instrumentation, equipment, and methodology to repair or prevent en-
vironmental degradation from point and non-point sources of pollution. This work
provides the new or improved technology required for the control and treatment
of pollution sources to meet environmental quality standards.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/2-77-202
October 1977
MEASUREMENT OF POLYCYCLIC ORGANIC MATERIALS
AND OTHER HAZARDOUS ORGANIC COMPOUNDS
IN STACK GASES
State of the Art
by
Peter W. Jones, JoAnn E. Wilkinson, and
Paul E. Strup
Battelle, Columbus Laboratories
505 King Avenue
Columbus, Ohio 43201
Contract No. 68-02-2547
Project Officer
Roy L. Bennett
Emissions Measurement and Characterization Division
Environmental Sciences Research Laboratory
Research Triangle Park, North Carolina 27711
ENVIRONMENTAL SCIENCES RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
RESEARCH TRIANGLE PARK, NORTH CAROLINA 27711
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DISCLAIMER
This raport has been reviewed by the Environmental Sciences Research
Laboratory, U.S. Environmental Protection Agency, and approved for publica-
tion. Approval does not signify that the contents necessarily reflect the
views and policies of the U.S. Environmental Protection Agency, nor does
mention of trade names or commercial products constitute endorsement or
recommendation for use.
ii
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ABSTRACT
This report documents and reviews state-of-the-art methods for the
measurement of polycyclic organic matter (POM) and other hazardous organic
materials which are present in industrial stack emissions. Measurement meth-
ods for many hazardous compounds, such as POM and nitrosamines, are presented
and, where specific methods have not been previously reported, the sections
dealing with recommended methods provide useful guidance. Individual chap-
ters are devoted to analytical methodology and stationary source sampling
methodology, although an effective measurement strategy demands input from
each protocol. An attempt is made to present a unified approach to hazardous
organic emission measurement so that future studies may benefit through more
realistic intercomparisons and more precise and accurate measurements.
This report was submitted in fulfillment of Contract No. 68-02-2547 by
Battelle, Columbus Laboratories under the sponsorship of the U.S. Environ-
mental Protection Agency.
iii
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CONTENTS
Abstract ill
Figures vi
Tables vi
Acknowledgment vii
1. Introduction 1
2. Conclusions and Recommendations 2
3. Analytical Methodology 3
Introduction 3
Polycyclic organic materials 3
Polychlorinated biphenyls and polychlorinated
naphthalenes 7
Nitrosamines 9
Other hazardous organic compounds 12
4. General Analytical Methods 16
Separation by high performance liquid chromatography . . 16
Spectroscopic screening techniques 21
Identification and quantification 24
5. Sampling Methodology 36
Introduction 36
Review of acceptable methods-recommendations 37
References 52
v
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FIGURES
Number Page
1 Overall analytical strategy 17
2 Sequential separation - Reverse phase HPLC 18
3 Principles of GPC 20
4 Reconstructed ion chromatograms of residual
oil combustion effluents 31
5 Mass spectrum of benzfluoranthenes 32
6 Mass spectrum of benzpyrenes 33
7 Adsorbent sampling system 38
8 Sot.rce assessment sampling schematic 40
9 Sampling handling and transfer-nozzle, probe, cyclones,
e.nd filter 44
10 Sampling handling and transfer - XAD-2 module 46
TABLES
Number Page
1 Organic species separable by various GC column types 26
2 Recoveries in stack sampler validation study 49
3 Maximum recoveries for sampler validation with
more volatile compounds 50
vi
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ACKNOWLEDGMENTS
We wish to acknowledge support from the Environmental Sciences Research
Laboratory, U.S. Environmental Protection Agency. The Project Officer for
this program was Dr. Roy L. Bennett, under whose direction this work was
conducted. Special acknowledgment is given to Drs. Kenneth T. Knapp and
Roy L. Bennett for many helpful discussions during the course of this program.
vii
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SECTION 1
INTRODUCTION
Together with the long overdue increase in awareness of environmental
contamination, an urgent need has arisen for reliable methods for the measure-
ment of pollutant species. This report is concerned with the state-of-the-art
methods for measurement of hazardous organic compounds in stack gases. Al-
though the chemical analysis methodologies described here are applicable to
organic materials from any source, the sampling methods and sample preparation
descriptions pertain to stack gas emissions.
The goal of this report is to present a discriminating review of recent
measurement methods for hazardous organic compounds. While not pretending to
be an exhaustive bibliography, it attempts to provide an effective source of
reference for future measurement problems. Measurement methods for many
hazardous compounds, including POMs and nitrosamines, for example, are pre-
sented in detail. However, where specific methods have not been previously
reported, the sections dealing with generally recommended methods will fre-
quently provide useful guidance.
The rationale for a report which reviews and recommends methods for the
measurement of hazardous materials which may potentially enter the environ-
ment, is the singular lack of agreement over which experimental methods are
appropriate. Thus, this document is an attempt to provide a more unified
approach to the measurement of hazardous organic pollutants, with the result
that future studies may benefit through providing more realistic intercompar-
ison, and more precise absolute measurements. The two chapters which follow
are separately devoted to analytical methodology and sampling methodology,
although an effective measurement strategy demands input from each protocol.
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SECTION 2
CONCLUSIONS AND RECOMMENDATIONS
In the measurement of organic materials present in stack gases, it is
evident that the three distinct areas of importance are sampling, sample
preparation, and analysis. The degree of confidence in each area varies
depending upon the species sought, but in general there is most confidence in
analysis, ar.d probably least in sample preparation or sampling.
Significant recent analytical advances have been made through the use of
high performance liquid chromatography and capillary columns in gas chromato-
graphic separations; further development of these important separation tech-
niques and t.he efficient interface of the former with mass spectrometry would
be very desirable. The further development of the interface between gas
chromatography and infrared spectroscopy, and an examination of the utility of
negative ion mass spectrometry for the analysis of electron capturing species
such as PCBs:, should be undertaken.
While current extraction and sample recovery procedures generally show
good efficiency, further research into sample recovery from dilute solutions
is required, in view of losses of more volatile species.
Present: stack sampling methods involving cyclones, filters, and polymeric
adsorbents are a very significant improvement over earlier methods, but are
relatively untried in field sampling situations. It would be highly desirable
for field sampling studies to be carried out in order to provide complete val-
idation of 1:hese methods under real-world conditions.
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SECTION 3
ANALYTICAL METHODOLOGY
INTRODUCTION
In this chapter we are concerned with analytical methods for the quanti-
tative analysis of hazardous organic materials which have been sampled from
stack gases. Preliminarily, recent analytical methods for specific compounds
are reviewed; for simplicity, materials of concern have been sub-divided into
four categories:
• Polycyclic organic materials (POM)
• Polychlorinated biphenyls (PCS) and polychlorinated
naphthalenes (PCN)
• Nitrosamines
• Other hazardous organics
Following the review of recent work is the section entitled "General Analytical
Methods". This section describes state-of-the-art analytical methodologies
which are most appropriate for measurement of trace quantities of organic
materials, which may be sampled from stack gases by methods described in the
subsequent chapter.
POLYCYCLIC ORGANIC MATERIALS
POMs are one of the largest known groups of carcinogenic materials which
are emitted in combustion effluent streams. Most current analytical tech-
niques involve some type of chromatographic separation and a spectroscopic
means of detection. Gas chromatography (GC) has become the most commonly
applied chromatographic procedure for POMs, and has been used with a variety
of detector systems. Although the most selective and sensitive detector
which has been used for POM measurements is the mass spectrometer, other
detectors have proved useful in specific circumstances.
Numerous researchers have investigated the application of GC to the sep-
aration of polycyclic organic materials. Burchfield (1,2) separated POMs on
a column of 6 percent Dexsil 300 on 110/120 mesh Anakrom A. He has described
a direct isolation and injection system for the analyses of POM in air par-
ticulate samples. POMs were stripped off ground glass filters by means of a
stream of heated (300 C) inert gas, with the stripping tubes directly con-
nected to either the cooled GC column or a 6.5 mm x 120 mm glass precolumn.
The sample was introducted by heating the precolumn from 80 to 450 C or by
temperature programming the GC column from 70 to 300 C. The effluent was
monitored by both an electron capture detector and a gas phase spectrofluo-
rometric detector connected by a 300 C stainless steel transfer line. The
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excitation and emission wavelengths were optimized for the POM of interest,
the spectro::luorometer optically resolved isomers such as benzo[a]pyrene (BaP)
and benzo[eIpyrene (BeP) which were not chromatographically resolved. The
minimum detectable levels of selected POM for this method were on the order of
10 ng, although the detector would be liable to interference from non-POM
species, unless a preliminary liquid chromatographic cleanup was added.
Mulik (3) has described a similar procedure for the analysis of BaP in
particulate samples. Filter extraction was initially accomplished by means
of ultrasonic homogenation with cyclohexane solvent; the solution was filtered
and concentrated. An aliquot of this solution was evaporated onto a 4 cm^
glass fiber filter placed into a small glass tube, inserted in a loop of a
high temperature valve oven and then sublimed (420 C) into the GC column. The
6 ft x 1/4 in OD glass column was packed with 6 percent Dexsil 300 + 6 percent
Dexsil 400 on Chromosorb W held isothermally at 280 C. The detector was a gas
phase spect;:ofluorometer equipped with a quartz flow through cell held at 350
C. Optimum detector response for BaP was found to be an excitation wavelength
of 360 nm and an emission wavelength of 404 nm. The detectable limit was 50
ng of BaP. This clearly reflects the difficulty of designing a gas cell to
accommodate an entire eluting GC peak, and ensuring complete optical illumina-
tion of (and emission from) the cell, since liquid phase spectrofluorimetry
may achieve two orders of magnitude greater sensitivity.
Dexsil 300 has become a very widely used column for POM separation, as
this appears to give slightly better resolution than OV-101, OV-17, or SE-30,
for example, in conventional packed columns. Herman (4) has used a 6 foot
Dexsil 300 column to separate both POMs and PCBs simultaneously. However,
satisfactory capillary columns coated with Dexsil do not appear to have been
prepared at the present time.
The work of Lee and Novotny (5) is a representative example of high per-
formance POlyi separations using capillary columns. In this work, filtered
ambient particulate extracts are preliminary cleaned up by chromatography on
a Sephadex LH-20 column using isopropanol as the mobile phase. Further frac-
tionation was obtained by HPLC on oxypropionitrile/porasil C with n-hexane as
the mobile phase, prior to GC separation. Gas chromatography is performed on
an 11 m x 0.26 mm ID glass capillary column coated with SE-52 methylphenyl-
silicone stationary phase (temperature programmed from 70-240 C at 2 C/min.
The separation thus obtained is among the best so far achieved in the analysis
of POMs in complex mixtures. Detection of the eluting GC peaks was accom-
plished through electron ionization mass spectrometry, the whole capillary
GC-MS analysis offering as good as any separation so far reported in the GC-MS
analysis of POMs. Fourier transform proton NMR was used to identify methyl
isomers of POMs and to verify GC-MS results.
Specific interest in the quantification of benz[a]pyrene (BaP), since
this is one of the more hazardous POMs, and partly because of the interest in
BaP generated by Sawicki's early analytical methods (see latter), has led to
the development of specific GC methods for BaP analysis. A novel GC column
has been developed and verified by Janini (6). BaP is separated from its
isomer BeP with a nematic liquid crystal column. The column, from 2.5 to 20
percent N,N'bis(p-methoxybenzylidene)-a,a'-bi-p-toluidine (BMBT) on 100/120
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mesh HP Chromosorb W, was temperature programmed from 185-265 C at 4 C/min in
order to separate and resolve a complex mixture of polycyclic hydrocarbons.
The more recent use of the butoxybenzylidine isomer (BBBT) (7) has demonstra-
ted that this is a more satisfactory column from a standpoint of column bleed.
Jones (8) has made extensive use of the latter column for BaP determination
by GC-MS; the still significant column bleed necessitated isothermal opera-
tion. A 1 foot column using 1 percent BBBT on Chromosorb W at 230 C was
found to give excellent separation of all 5-ring POMs; 9, 10-diphenylanthra-
cene proved to be an ideal internal standard for quantification at the pg
level by specific ion monitoring (SIM).
Harrison and Powell (9) described a method of analysis which also separ-
ates BaP from BeP. Since the Ni electron capture detector response ratio of
BaP to BeP is 85:1 at a pulse space of 150 sec, this detector is highly selec-
tive for BaP. The samples were chromatographed on a 5 foot x 14 in OD column
packed with 3 percent polymetaphenoxylene on a support of 70-85 mesh acid
washed and silanized Celite, using a column and detector temperature of 285 C.
Other GC methods used for determination of POM include chromatography on
a 2 percent SE-30 with a support of Chromosorb G (80-100 mesh) (10). The
column eluent was split, part for analysis by a flame ionization detector and
the rest trapped for UV analysis at the optimum wavelength for each POM.
Zoccolillo (11) cleaned up extracted samples by TLC and then chromatographed
them on a 5 m x 2 mm ID stainless steel column packed with 1 percent SE-52
on a support of Chromosorb G (60/80 mesh) at 250 C. Bhatia (12) described a
method of preparing a 20 ft x 1/8 in copper column of approximately 0.4 per-
cent OV-7 on 60/80 mesh glass beads. With this column, resolution of benzo-
[kjfluoranthene, BaP, BeP, and perylene was obtained, which is not possible
on conventionally prepared OV-7 columns.
Gas chromatographic mass spectrometry (GC-MS) is the most useful tech-
nique for the measurement of trace quantities of POMs in environmental
samples. The high selectivity of mass spectrometry will frequently permit
resolution of non-isomeric species which are not chromatographically resolved.
Sensitivity at the nanogram level is routinely possible using wide range ion
detection; sensitivities of a few picograms may be achieved by means of
specific ion monitoring (SIM).
Lao (13,14) and Novotny (5) have described state-of-the-art GC-MS systems
for the analysis of POM compounds. Such GC-MS systems are interfaced with
minicomputers which provide versatile data handling. In studies by the former
author, samples were collected on filters, soxhlet extracted with cyclohexane,
and subjected to a Rosen separation on activated silica gel. The stainless
steel GC column, 12 ft x 0.125 in, was packed with 6 percent Dexsil 300 on
Chromosorb W (80/100 mesh), held at 165 C for 2 minutes and then programmed at
4 C/min until reaching 295 C. The electron energy used was 70 eV and the mass
range scanned was 14-350 amu at a scanning speed of 20 or 60 amu/sec. The
computerized data system measured relative retention times, calculated peak
areas, and subtracted spectral background for each peak. Quantification,
using internal standards, was achieved for amounts in the nanogram region.
Novotny has described fractionation of ambient air particulate extract using
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lipophilic-gel column chromatography and Sephadex LH-20 chromatography, fol-
lowed by HPLC using oxyproprionitrile chemically bonded to Porasil C. High
resolution capillary column GC-MS was used to monitor the progress of the
fractionatlon and to provide qualitative analysis of the enriched fractions.
GC separation was accomplished using an 11 m x 0.26 mm ID glass capillary
coated with SE-52, and was as good as any separations achieved for POM com-
pounds to date. Quantitative analysis was not attempted in this instance.
Liquid chromatography (LC) and thin layer chromatography (TLC) have been
used extensively for POM separations. Sawicki (15) and Zoccolillo (16) de-
scribe methods of determining POMs by TLC on alumina plates with fluorescence
detection while TLC on neutral aluminum oxide and acetylated cellulose, fol-
lowed by fluorescence detection, is described by Pierce and Katz (17). How-
ever, in the analysis of complex environmental mixtures, such resolution is
generally inadequate to facilitate measurement of large numbers of individual
species. Nevertheless, LC is frequently utilized in a preliminary cleanup
step prior to GC analysis of POMs, although there is no doubt that a more
efficient isolation of POM species in this manner can be accomplished by high
performance liquid chromatography (HPLC). Such prefractionation has been car-
ried out using silver impregnated 60 mesh silica gel eluted with 1 percent
acetonitrile in hexane to separate PAHs from Azarenes (18). Sawicki (19,20,
21) has described a suitable cleanup procedure involving separation of POMs
on activated alumina. HPLC has been used by several workers for the measure-
ment of environmental sample for POMs, and although demonstrated resolution
is presently lower than attainable by GC, the major drawback of HPLC measure-
ment techniques is their incompatibility with sufficiently sensitive and se-
lective detectors. A recent mass spectrometer interface introduced by Finni-
gan apparently suffers from very poor efficiency (5 percent or less) which
precludes satisfactory LC-MS analysis of POMs.
Most reported HPLC measurements of POMs have made use of either ultra-
violet (UV) or refractive index (RI) detection, although greater sensitivity
and selectivity can be achieved by fluorescence detection if there are no
internal quenching problems. Klimisch (22,23,24) describes HPLC analysis
schemes which achieve separation of the benzpyrene isomers. Using a packing
of HPLC-Sorl) polyamide-6 in a 1 m x 4 mm ID column with various polar sol-
vents, he obtains good separations (22). Detection limit with a 45 percent
acetylated column was rather poor, around 200 ng BaP (23). Cross-linked cel-
lulose acetate has been found to be a better column packing since it is gran-
ular and possesses a lower swelling capacity than regular cellulose acetate.
The structure is more uniform and thus has a greater permeability with lower
pressure than the above described system. Thus separation was achieved on a
250 x 4 mm stainless steel column of 35 percent HPLC-Sorb, Cel-Ac-30X with a
solvent system of 2:1 ethanol-dichloromethane at a pressure of 3 atm, with a
flow rate oil 42 ml/hr. The UV detection limit measured at 297 nm was 30 ng
BaP/5 yl injection by the use of a fluorescence detector with a 326-380 nm
exitation filter and a 377 nm emission filter. Since interferring anthracene
often exists in complex POM mixtures, it was necessary to cleanup the sample
on an aluminum oxide LC column prior to the HPLC procedure.
Boden (25) compared three HPLC column-solvent systems using a UV detector
set at 383 iim for quantitation of BaP and at 275 nm for less selective measure-
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merits. The three systems are:
(a) 24 cm x 3.2 mm Lichrosorb column eluted with
cyclohexane at a flow rate of 0.2-0.6 ml/min.
The detection limit was 0.1 ng.
(b) 30 cm yBondpak C^Q eluted with 60:40 acetonitrile-
H2
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Most reported GC separations of PCBs and PCNs utilize a combination of
QF-1 with either of OV-1, OV-17, OV-101, or SE-30, as the stationary phase.
Fishbein (29) has reviewed numerous chromatographic techniques for PCBs and
describes :he use of a tritium electron capture detector in conjunction with
a 6 ft x 1/8 in OD glass column packed with 6 percent QF-1 and 4 percent SE-
30 on acid washed Chromosorb W. The operating conditions were: column tem-
perature 200 C, nitrogen carrier gas, injector temperature 250 c, and the
detector base temperature 250 C. Musty et al (30) have described the analysis
of PCBs on a 5.5 ft x 4 mm glass column packed with 1.5 percent OV-17 and 1.95
percent QF-1 on Gas Chrom Q (100-120 mesh) at 200 C using argon carrier gas;
the 63 Ni electron capture detector was maintained at a temperature of 300 C.
Greichus e: al (31) achieved PCB separations using a column packing of 15
percent QF--1 and 10 percent DC-200 silicone (1:1) on 80/100 mesh Chromosorb
W, in addition to a 3 percent OV-1 on 60/80 mesh Gas Chrom Q which was util-
ized in a (JC-MS application.
Krupc:.k et al (32) have investigated the application of capillary gas
chromatography to the analysis of PCBs, and found that metal capillary columns
coated with Apiezon L or OV-101 were inferior to 50 or 60 m glass capillary
columns coated with OV-101. Preferred chromatographic conditions were:
column temperature 200 C; injection port temperature 250 C; nitrogen flow
rate 0.3-0.7 ml/min. These workers additionally reported the use of capillary
column GC-MS analysis of PCBs using a 30 m glass capillary column coated with
SE-30 at 200 C. Both the injection port and the ion source temperature were
maintained at 250 C; the helium flow rate was 0.5 ml/min. Mass spectra, used
for the identification of isomeric PCBs, were obtained from nanogram quantities
of the unknowns. Sissons and Welt (33) have utilized a 50 ft Scot Apiezon L
column for the measurement of PCBs in commercial mixtures, but achieved some-
what lower resolution than the previous workers.
Quantisation of PCBs obtained by perchlorinating to decachlorobiphenyl or
by dechlorination to bicyclohexyl and subsequently detecting these derivatives
by gas chrcmatographic methods has been described by Berg et al (34). How-
ever, it should be cautioned that unpublished reports have indicated that
perchlorin£.tion with antimony pentachloride is susceptible to interference
from decachlorobiphenyl which appears to be generated during the reaction (35),
from sourctis other than the PCB content of the sample.
PCBs may be catalytically dechlorinated over Pt or Pd catalysts and "total
PCB" subsequently quantified by measurement of biphenyl using GC, as described
earlier. Eowever, since this dechlorination is not always quantitative, and.
in the absence of mass spectrometric detection, catalylic perchlorination is
preferred in view of the greater sensitivity of electron capture detectors
towards the perchlorination product. Perchlorination of PCBs has been car-
ried out by Berg et al (34), using antimony pentachloride, the resultant solu-
tion was then treated with 20 percent HC1 to prevent the precipitation of
oxychloride. The aqueous phase was extracted with warm benzene, shaken with
aqueous bicarbonate, and finally with water. The organic layer was dried over
anhydrous sodium sulfate. Decachlorobiphenyl was detected by a tritium detec-
tor at 215 C after chromatography on a 5 percent SE-30 column at 215 C, with
an injectoi temperature of 220 C.
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Armour (36) found that, for PCBs of low chlorine content, Berg's method
was not reproducible, and attributes this to volatilization during evaporation
of the solvent from the sample. It was recommended that the PCB sample should
be perchlorinated in a 0.1 ml solution of chloroform and the derivative chro-
matographed on either a 1 percent OV-101 or a 3 percent Dexsil column using
an EC detector.
The main drawback of the perchlorination measurement method is that bi-
phenyl must be completely removed from the sample prior to perchlorination to
avoid erroneously high levels of decachlorobiphenyl. Brinkman et al describe
a high liquid chromatographic (HPLC) technique for the analysis of PCBs.
Separation was carried out on a 25 cm x 3 mm silica gel column using n-hexane
as the mobile phase. The detector used was a thermostated UV cell with a
volume of 8 mm-* and a 1 cm path-length, detection being carried out at 205 nm.
It is recommended that a similar procedure should be used to remove biphenyl
from PCBs prior to quantitative analysis by perchlorination techniques.
When PCBs and PCNs are to be measured by means of GC with electron capture
detection, it is advisable to carry out a preliminary chromatographic cleanup
step for the removal of commonly occurring pesticides which would otherwise
interfere with subsequent analysis. Column chromatography on Florisil (37,38)
is often used for cleanup of samples, however, this is not effective for sep-
arating PCBs from all other chlorinated pesticides. Armour and Burke (39)
used a column of silicic acid-Celite to elute PCBs with petroleum ether to
elution of pesticides (such as DDT and its analogs). The mobile phase was a
mixture of acetonitrile, hexane and methylene chloride. Berg et al (34) found
that the reproducibility of this method was poor and thus developed a technique
involving a column of Fischer coconut charcoal. PCBs were eluted with benzene
followed by a Florisil cleanup prior to quantitation by EC gas chromatography.
The separation of PCBs from DDT has also been accomplished by means of absorp-
tion liquid chromatography on a Merkosorb SI-60 column, using light petroleum
solvent (38), and by using Perisorb A with n-hexane as the mobile phase (40).
NITROSAMINES
The majority of nitrosamine analyses which have been reported have con-
cerned measurements on food products. Very few examples of nitrosamine
analyses on ambient atmospheres have been described (41,42), and none have
specifically concerned the measurement of nitrosamines in stack gas effluents.
The following review of analytical methodology describes a variety of tech-
niques which may be generally applied to stack gas effluent.
A considerable proportion of reported nitrosamine measurements involve
derivatization, oxidation, or reduction of the nitrosamine, followed by gas
chromatographic analysis utilizing electron capture detection. Remarkably
good sensitivities have been achieved by these techniques, frequently as low
as 10-100 pg, but despite the use of relatively selective electron capture
detectors, structure confirmation is nevertheless lacking from these tech-
niques. The increased resolution of capillary GC columns is an aid to both
qualitative analysis and sensitivity, as discussed subsequently. Furthermore,
the use of mass spectrometric detection may facilitate qualitative, analysis.
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A serious problem which is associated with the measurement of volatile
compounds such as nitrosamines, is the maintenance of sample integrity during
extraction, concentration, and chromatography. A study by Jones et al (43)
demonstratad that typical recoveries for N-nitrosodiethylamine were 65 to 85
percent during sample handling. Castenaro (44) has described a technique for
derivatizing volatile nitrosamines to oxonium salts, in order to avoid sample
losses. Nitrosamines were reacted with triethyloxonium fluoroborate in di-
chloroethane, and after volume reduction, the oxonium salt was oxidized to
nitramine prior to subsequent analysis by GC with electron capture detection.
Recoveries of approximately 90 percent have been achieved by this technique.
Alliston et al (45) have reported the reduction of nitrosamines electro-
chemically to secondary amines which were subsequently derivatized to poly-
fluorinated amides utilizing heptafluorabutanoyl chloride. These derivatives
were chromatographed on a 2.75 m x 2 mm 15 percent column of FFAP at 60 C and
detected by a 6%i electron capture detector operated at a pulse space of 500
Us and at a temperature of 250 C. The lower limit of detection was approxi-
mately 100 pg.
Eisenbrand (46) utilized acid catalyzed denitrosation and derivatization
with heptafluorobutylchloride to form electron capturing derivatives of vol-
atile nitrosamines. Separation was obtained on 5 percent SE-30 column, with
a detection limit of 100-200 pg using a Ni electron capture detector.
Nitrosamines have been oxidized to nitramines with peroxytrifluoroacetic
acid as described by Sen (47). Chromatographic separation of these deriva-
tives was accomplished using a 6 ft, 10 percent Carbowax 20 m column main-
tained at 150 C, with a tritium electron capture detector at 210 C; a detec-
tion limit of approximately 10 pg was achieved with this system.
The thermionic (alkali flame ionization) detector equipped with various
salt tips has been found to be selective for nitrogen containing compounds.
The rubidium chloride thermionic detector has been shown to have a detection
limit of C.3-0.5 ng by Gough and Sugden (48). Samples were chromatographed
on 15 percent FFAP column (5.1 m x 2 mm) at 160 C. The injection port temp-
erature wes 160 C and the detector temperature 250 C. However, this detec-
tor was fcund to be less stable and sensitive than the conventional flame
ionizatior: detector.
Howard et al (49) analyzed nitrosamines, in amounts as low as 0.1 ng by
the use of a coiled potassium chloride thermionic detector following separa-
tion on a 3 m x 4 mm 10 percent Carbowax 1500 + 3 percent KOH column main-
tained isothermally at 80 C for 3 minutes and then programmed to 120 C at 10
C/min. Linearity of the detector response was achieved up to 50 ng with a
lower limit of detection of 0.1 ng. Hawabata (50) reports that the lifetime
of a potassium bromide thermionic detector can be extended by the use of a
crystal detector system as opposed to the coil type detector reported by
Howard (4<>) . The detection limits are similar for both systems.
Rhoacles and Johnson (51) have described the conversion of a Coulson
liquid conductivity detector into a specific nitrosamine detector by using
argon caririer gas and removing the hydrogenation catalyst from the quartz tube.
10
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The furnace was operated in the range of 400-600 C to pyrolyze the nitrosamine,
and ammonia was detected as the thermal degradation product. Chromatography
was achieved in this instance on a 10 percent Carbowax 1500 column temperature
programmed from 70-150 C at 5 C/min. Sensitivities down to 1 nanogram were
achieved by this system. Essigmon (52) has also described use of a Coulson
detector for nitrosamines, at sensitivities down to about 10 ng. In this
work a 20 percent Carbowax 20 M precolumn was utilized in order to permit
large injections to be made, with facilities for venting the solvent peak.
Fine et al (53) have described a thermal energy analyzer which can be
used as a selective and sensitive detector for n-nitroso compounds including
both volatile and non-volatile nitrosamines. The sample (in a solution of
dichloromethane) is injected into a flash vaporizer and swept into a heated
catalytic pyrolysis chamber by the argon carrier gas. The nitric oxide pro-
duced is reacted with ozone to give excited NO-* which decays with emission
of near infrared light, whose intensity is proportional to the original ni-
trosamine concentration. Dimethylnitrosamine obtained from air samples was
chromatographed at 180 C on a Chromosorb 103 column, and could be detected
at a level of 1 ppb. (41) Utilizing a column of 15 percent FFAP on Chromo-
sorb W (6.5 m x 2 mm) at 200 C, analysis of volatile N-nitrosamines at con-
centrations down to 10 yg/1 (0.01 ppt) in samples of drinking water was
achieved. (54) The application of this detector system to high performance
liquid chromatography has subsequently been described (41).
The analysis of N-nitrosodiethylamine by methane chemical ionization GC-
MS has been described by Jones et al (43). Quantification was carried out by
specific ion current integration for the molecular ion using pyridine as the
internal standard. The detection limit achieved was only 1 to 10 ng in this
instance, although a one to two order of magnitude improvement should be
attainable by specific ion monitoring (SIM). Gas chromatographic separation
was achieved in this instance using a 6 ft 3 percent Silar 10 CP column,
which is preferable to Carbowax for GC-MS work on account of the low column
bleed.
Capillary GC separations of nitrosamines have been described by Pelli-
zari (42) and Heyns and Roper (55). The former study used a 100 m glass 0V-
101 SCOT column, while the latter described the use of a PDEGS 26 m glass
capillary column. Both systems used mass spectrometric detection, the great-
est resolution and sensitivity being achieved by Pellizari, but no detection
limits were given.
Gough and Webb (56,57) have described a high resolution GC-MS analytical
system with a sensitivity of approximately 1 ng. Other high resolution mass
spectrometric analyses of nitrosamines have been described by Crathorne (58),
Telling (59), and Bryce (60).
The use of HPLC in the analysis of nitrosamines has been described by
Cox (61). One method is to detect an amine derivative of the reduced nitros-
amine following separation using either a 1 m x 2 mm column of Durapac Carbo-
wax 400-Corasel or a 50 cm x 2 mm Carbowax-silica gel Si-60 column. In both
cases the mobile phase was 25 percent dioxan-2,2,2,4-trimethylpentane with a
flow rate of 0.52 cm/sec and a 26 cm/sec respectively. A second method is a
11
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direct N-ni1:rosamine detection method using a 1 m x 2 mm column of di(2-cyano-
ethyl) ether as the mobile phase. The flow rate was 0.6 ml/min. The direct
analysis was; more sensitive but more prone to interferences than the reduction
method. DeCection limits were between 1 and 10 yg/kg using variable wavelength
UV detection,
Klimiseh et al (62) have derivatized nitrosamines by denitrosation and re-
action with 7-Cl-4-nitrobenzo-2-oxa-l,3-diazol (NBD-C1) to form fluorescent
compounds. Separation of the NBD derivatives was by HPLC on a 250 x 21 mm
silica gel column. The solvent system was cyclohexane:acetic acid ethyl ester:
isopropanol (50:50:0.5) with a flow rate of 16.5 ml/hr. The UV (473 ran) detec-
tion limit was 25 ng/1.5 yl. This was lowered to 0.5 ng/5 pi by use of a
fluorescence detector with an excitation wavelength of 365 nm, and detection at
451 nm.
Separation of nitrosamines can also be achieved by liquid chromatography
on Sephadex LH-20 with detection by UV analysis at 230-235 nm. (63) A TLC
cleanup procedure is described by Eisenbrand (64). Walters et al (65) de-
scribe a po!Larographic and a UV irradiation technique. Reasonable nitrosamine
specificity is obtained by a sensitive plasma chromatographic technique with a
detection limit of 10 pg which has been described by Karasek and Denney (66).
OTHER HAZARDOUS ORGANIC COMPOUNDS
Vinyl Chloride
Vinyl chloride monomer is a widely used industrial chemical, which has been
recently connected with a rare liver cancer. Most published analytical schemes
involve collection of ambient air samples on activated charcoal, followed by
thermal or solvent desorption with carbon disulfide prior to GC analysis. The
majority of GC separations have been carried out using Chromosorb 102. Detec-
tion is most typically by flame ionization detector; the highest reported sen-
sitivities Eor both this technique and GC-MS being 0.1 ng.
PurcelL (67) has separated vinyl chloride on an 18 in x 1/8 in column of
Chromosorb L02 (80/100 mesh), and recommends thermal desorption from charcoal
at 260 C for recovery of vinyl chloride due to the toxicity of carbon disul-
fide. The 3C column was maintained at ambient temperature during sample de-
sorption, vinyl chloride was eluted at 70 C within 4 minutes. Eluting peaks
were detectad by flame ionization.
Vinyl chloride samples obtained from stationary stack sources have been
analyzed by gas chromatography on a Chromosorb 102 column held isothermally at
155 C. (68) A detection limit of 0.1 to 0.4 ng has been reported by flame
ionization detection. Analysis of samples containing down to 6 ppb vinyl
chloride was achieved by Ives (69) using a 6 ft x 4 mm column of Poropak Q at
120 C, following thermal desorbtion from Tenax GC. A similar analytical scheme
has been reported by Ahlstrom (70), who made use of activated charcoal for
sample collection. Other separations of vinyl chloride on Carbowax 20M (71)
and Chromosorb 101 (72) have been reported by Ravey and Meyers, respectively.
However, it should be remembered that all analyses involving a single GC column
and a non-selective detector must be confirmed by a supplementary analytical
technique-
12
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Two GC columns have been used by Going (73) for separation and confirmation
of the presence of vinyl chloride monomer in ambient air. Analysis was accom-
plished using a flame ionization detector after separation on a 6 ft x 1/8 in
10 percent column of DC 200 Supelcoport at 150 C (injector and detector 210 C).
Confirmation of these results was obtained by chromatography on 6 ft x 1/8 in
column of 0.4 percent Carbowax 1500 on Carbopak A at ambient temperature. The
injector was 180 C and the detector 210 C. Recovery of vinyl chloride was 90
percent with a detection limit of 10 ppb in ambient air.
Lao (74) et al utilized a GC-MS system in order to perform qualitative
and quantitative analyses for vinyl chloride monomer. Chromatographic separ-
ation was achieved using a 6 ft x 1/8 in column packed with Chromosorb 102
held isothermally at 145 C; the injector, detector and mass spectrometer source
were at a temperature of 250 C. The reported detection limit was 0.1 ng.
The use of a Hall detector has been described by Ernest and Van Lierop
(75). The Hall detector is a microelectrolytic conductivity detector which
determines the amount of HC1 formed by reducing the chromatographed sample
with hydrogen in a 15 cm x 2 mm ID quartz tube. Preliminary GC separation was
accomplished isothermally at 90 C on a 4 m x 1/8 in stainless steel column of
5 percent SE-30 on Chromosorb G. Detection limits were in low nanogram region.
Baumgardner et al (76) have developed a specific chemiluminescence detec-
tor for the GC analysis of vinyl chloride monomer. Chromatographic separation
was achieved on a 10 ft x 3/16 in Teflon tube packed with 0.4 percent Carbowax
1500 on Carbopak A at ambient temperature. N2 is used as carrier gas at 30
cc/min. The detector measures the chemiluminescence produced by the reaction
between vinyl chloride and ozone. The wavelength range monitored was 4000-
4500 A, the minimum detectable quantity was 60 ppb in air.
Cedergreen et al (77) have quantified the amount of vinyl chloride present
in a sample by a coulimetric method, which is based on the determination of
chloride content via coulimetric titration in aqueous of acetic acid. The
sample is combusted in 02 and the HC1 formed is subsequently titrated with
silver ions. The detection limit reported was rather poor at approximately 1
ppm vinyl chloride.
Freund and Sweger (78) have described a specific analytical procedure
based on Stark modulated absorption of IR laser radiation. By superimposing
a static electric field of appropriate magnitude and sign, on an electric field
sweep and a modulating field, it is possible to Stark shift several vinyl
chloride IR transitions into exact coincidence with the laser and subsequently
to use phase sensitive detection to observe the absorption signal. This sig-
nal is directly proportional to the concentration of the sample, but no de-
tection limit was reported.
Bischloromethyl Ether
Parkes et al (79) have described a gas Chromatographic method for the
analysis of organics including vinyl chloride and bischloromethyl ether (BCME).
BCME was initially trapped on Chromosorb 101 and thermally desorbed at 220 C
13
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onto a GC column packed with Chromosorb 101. The column was programmed to
200 C.at 50 C after the sample had been desorbed. The flame ionization detector
was at a temperature of 250 C. Helium at a flow rate of 40 ml/min was the
carrier gas;. Detection was at the ppb level.
Solomon and Kallos (80) have described the formation of electron captur-
ing derivatives of BCME and chloromethylmethyl ether by reaction with the
sodium salt, of 2,4,6-trichlorophenate. Chromatography was accomplished iso-
thermally £.t 140 C using a 6 ft x 1/4 in glass column packed with 100/200 mesh
glass beads coated with 0.1 percent QF-1 and 6 percent OV-17. The temperature
of the sample injector (on-column) and the detector were 175 and 250 C, respec-
tively.
Collier (81) measured BCME at the ppb level by high resolution mass spec-
troscopy. The intensity of ions at m/e 78-9950 (C1CH2-0-CH2+) was measured at
a resolution of 3500. Shadoff et al (82) and Evans et al (83) have both ob-
jected to this procedure because of the possibility of interferences from other
species which may yield the ion monitored, specifically from chloromethylmethyl
ether. Evans has also pointed out the possibility of adsorption, regeneration
and possible decomposition of BCME in the mass spectrometer. Shadoff.has
analyzed for BCME by SIM GC-MS using the m/e 79 and 81 ions simultaneously.
Identification was dependent on the simultaneous response of m/e 79 and m/e 81
in a 3:1 ratio at the correct retention time on a 4 ft column of Chromosorb
101 at 130 C. Detection was achieved down to a level of 10 ng/yl. Evans
obtained greater specificity by monitoring m/e 78-9950 by high resolution mass
spectrometry after gas chromatographic separation on a column of 30 percent
PEG adipate at 150 C, using resolution of 3800. The lower limit of detection
was 0.01 ppD with a 10 1 air sample.
Hydrazines
Hydrazlnes have been measured by various techniques such as titrations,
GC and TLC. Dee and Webb (84) have described a GC system that reduces the
commonly encountered problems of adsorption and peak tailing. They employed
aim column of 10 percent 2-hydrazinopyridine (HyPy) on Fluoropak support
isothermally maintained at 80 C, however, this column packing is quite un-
stable. Santacesaria and Guiffie (85) have described a GC column packing
which is much more stable than HyPy but still avoids the complications of peak
asymmetry and adsorption. This optimum column packing is a 12 percent mix-
ture of triathanolamine and tetraethylenpentamine (2:5) on a support of 30-60
mesh Chromosjorb W, which has been shown to be effective for separation of
hydrazine and water.
Flala and Weisburger (86) have described a TLC system which is as sensi-
tive as the GC method of Dee and Webb, and which can resolve the dihydrochloride
salts of hyc'.razine, methylhydrazine, 1,1-dimethylhydrazine and 1,2-dimethyl-
hydrazine. It uses precoated (Avicel cellulose 25 ym thick) glass plates
developed with 2-propanol-water-conc. HC1 (130:40:30). Folen-Ciocateau reagent
was sprayed on the plates and after 20 min they were exposed to NHg fumes to
develop the blue spots of hydrazines. The limit of detectability was 0.12 yg/
14
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Epoxides
Epoxide derivatives of polycyclic aromatic hydrocarbons are thought to be
either precursors for carcinogens or carcinogenic in themselves, Morreal et
al (88) have separated dime thyIbenz(a)anthracene epoxides from the correspond-
ing phenols and dibls by column chromatography on 5 percent deactivated alumina
eluted with 3 percent dioxane in hexane. They were then derivatized to their
heptafluorobutyric esters and quantified by electron capture GC on an 8 ft x
2 mm column of 3 percent OV-17 on Gas Chrom Q at 225 C. Quantification was
achieved with a detection limit of 1-10 ng.
Benzo(a)pyrene-4,5-epoxide has been separated on a reverse phase Perma-
phase ODS column with a MeOH-H20 gradient from 30:70 percent to 70:30 percent
at 3 percent/min at 50 C. Identification was achieved by mass spectrometry,
HPLC retention times, and UV analysis (89).
15
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SECTION 4
GENERAL ANALYTICAL METHODS
The objective of this section is not only to provide a description of
individual organic analytical techniques, but also to present a generally
applicable iHialytical scheme which will be useful for either the quantitative
analysis of grossly complex mixtures, or to seek specific organic species in
complex mixtures.
An overall analytical strategy offering a maximum probability of
successful qualitative and quantitative analysis of a complex organic
mixture includes liquid chromatographic (LC) separation followed by deter-
mination of the compound classes present in the resultant LC fractions, and
qualitative and quantitative analysis (90). Preliminary separation may be
made by either conventional column chromatography or high performance liquid
chromatography (HPLC).
Preliminary analysis will consist of screening each HPLC fraction by a
combination of techniques such as infrared spectroscopy (IR), nuclear
magnetic resonance (NMR) spectroscopy, and high-resolution mass spectrometry
(HRMS). Having thus identified the classes of organic compounds which are
present in each of the fractions, qualitative and quantitative analysis may
be carried cut by gas chromatographic-mass spectrometry (GC-MS), gas
chromatographic-infrared spectroscopy (GC-IR), gas chromatography (GC),
nuclear magnetic resonance (NMR), and high performance liquid chromatography
(HPLC). HPLC in combination with NMR, IR, and mass spectrometry (MS) may
be utilized exclusively for identification and quantification of very polar
and ionic compounds, since these species are not amenable to separation by
gas chromatography and have been largely ignored in earlier studies.
As can be seen in Figure 1, the separation into fractions and analytical
screening will be iterative procedures, in so far as separation techniques
will be reapplied as extensively as necessary until the screening techniques
indicate that the complexity of each HPLC fraction is sufficiently reduced
to permit qualitative and quantitative analysis.
SEPARATION BY HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY
In order to successfully separate and analyze a very complex mixture,
the use of multiple chromatographic techniques, or sequential analysis, may
be necessary (Figure 2). The use of high performance liquid chromatography
(HPLC) allow.? sequential analysis to be performed more quickly and efficiently
than conventional column chromatographic techniques.
16
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DISCARD
SAMPLE
EXTRACTION
SIZE SEPARATION
CLASS SEPARATION
IDENTIFICATION
QUANTITATION
ADDITIONAL
SEPARATION
FIGURE 1. OVERALL ANALYTICAL STRATEGY
17
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oo
M
o
1-0
co
CO
H
H
O
CO
CO
B
IT1
VERY NONPOLAR
GPC FRACTION
REVERSE PHASE LC
NONPOLAR
SCREENING
GC ANALYSIS
POLAR
VERY POLAR
SCREENING
HPLC ANALYSIS
-------
Separation by Size
The first step in the separation of a complex mixture is to separate by
size or molecular weight, using gel permeation chromatography (GPC). GPC
is an exclusion technique in which retention is based on a molecule's ability
to penetrate the pores of the chromatography support. Figure 3 illustrates
the principles of gel permeation chromatography. Large molecules elute with
the solvent front while small molecules totally permeate the support and
elute later. Within the range of elution volume, molecules can selectively
permeate the support and thus be separated. Supports must be chosen for
the exclusion limits that correspond to the molecular weight range that
one desires to separate. For more detailed information, the following books
and review articles should be consulted (91,92,93).
There are several advantages in using GPC as an initial separation
method. A knowledge of the molecular weight of an individual fraction can
dictate the choice of further separation steps such as gas or liquid
chromatography as discussed subsequently. Narrow molecular weight ranges
also allow simpler interpretation of the class separations that follow.
Finally, information concerning molecular weight is useful for final
identification purposes.
Gel permeation chromatography is the simplest form of high-performance
liquid chromatography. Its use will divide a complex multi-component
sample into mamageable fractions. Once Step 1 of sequential analysis is
completed, samples can now be further separated by class.
Separation by Class
In the previous section, we have seen how narrow molecular weight frac-
tions could be obtained from a complex mixture by separation on GPC columns.
The GPC fractions can now be further separated according to polarity by
bonded phase liquid chromatography.
Bonded phase liquid chromatography is a form of liquid partition
chromatography in which the stationary liquid is permanently chemically
bonded to the support. Although the mechanism of retention is no longer
strictly partition, bonded phases possess distinct advantages over liquid-
liquid systems. Since the stationary phase is bonded to the support, it
cannot be stripped off by the eluent and therefore precolumns are not
necessary. More importantly, gradient elution, an extremely important
technique which will be discussed shortly, can be performed with a wide
choice of solvents. Finally, a wide range of selectivity can be obtained
by the proper choice of chemically bonded phase.
In this second step of sequential analysis, a reverse phase bonded
support should be used. It has been shown that for similar solutes, a plot
of the log of retention time versus water solubility yields a straight line,
when using reverse phase columns with water-methanol mixtures as the mobile
phase (94). Since we have already obtained fractions of narrow molecular
weight, it can be assumed that retention will be roughly a function of the
particular functional groups attached to the molecule. We can therefore
«
19
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EXCLUSION
MOLECULAR
SIZE
OPTIMUM
MOLECULAR
WT
SELECTIVE PERMEATION
'm
TOTAL PERMEATION
ELUTION VOLUME
FIGURE 3. PRINCIPLES OF GPC
20
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obtain a rough class separation by performing gradient elution on high-perfor-
mance reverse phase column.
Functional Group Separation—
The fractions obtained from GPC can be further separated by reverse phase
HPLC using gradient elution. Figure 2 shows, once again, a rough guide to the
kind of separation one might expect. Very polar compounds will elute first
and very nonpolar compounds will elute last. The fractions which are collected
during this run may contain 1 or 2 components in a simple case of 100 components
in an extremely complex mixture. However, these fractions should be suffi-
ciently homogeneous to be screened by spectroscopic techniques for classes of
organic compounds. If screening techniques indicate that a fraction contains
compounds amenable to GC analysis, this route should be taken. Complex mix-
tures or mixtures containing compounds which cannot be run by GC should be
further separated by HPLC. Large ranges in solvent composition are given to
account for the molecular weight differences in a given class of compounds.
For example, naphthalene and coronene might be expected to elute towards the
two extremes of the POM range. Relative retentions for standard compounds of
interest should be determined prior to unknown analysis so that narrow frac-
tions can be obtained from the gradient run.
After Step 2 of this sequential analysis, a considerable separation of the
samples has been accomplished and effective screening techniques should now
be used to determine further cause of action.
SPECTROSCOPIC SCREENING TECHNIQUES
Separation of the sample into organic classes by HPLC will provide frac-
tions which can be screened for complexity and/or types of compounds which are
present. Identification of individual components is not intended in a screen-
ing technique, but rather the ability to discern the presence or absence of
interferring compounds in a given class, and to judge the overall complexity
of the mixture. In the case of the most complex mixture, screening will pro-
vide an indication of the type of separation needed to further fractionate
the sample. For simple mixtures, screening will be a step toward qualitative
and quantitative analysis.
The most useful technique used for screening is undoubtedly infrared
spectroscopy, although nuclear magnetic resonance spectroscopy and high-
resolution mass spectrometry may additionally prove to be effective.
Infrared Spectroscopy
Infrared spectroscopy has been, and still is, the^most widely used tool
for identification of organic compounds. One of the major uses of infrared
spectroscopy (IR) has been screening during the separation of complex organic
mixtures. It has provided functional group (especially on polar groups)
identification in such mixtures, it has been used to monitor or screen the
course of separation of the mixture, and ultimately it has been used to
identify the compounds present when the separation has resulted in sufficient-
ly simple mixtures. As with most analytical tools, less information is
obtainable when the mixture was very complex as compared to when the mixture
21
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was separated into smaller fractions. Now, however, the use of Fourier
Transform infrared systems (FT-IR), has clearly demonstrated that a major
increase in sample information can be obtained - even on complex mixtures -
through the use of the FT-IR dedicated computer to do spectral arithmetic.
Thus, as separation techniques are applied, IR should be used to monitor
the separation and identify the separated classes of species. Spectral sub-
traction should be used to magnify the differences between the separated
fractions. Whenever possible, this spectral arithmetic will be used to
minimize thii need of chemical separations.
Used :.n this manner, IR will provide a major source of structural
information to evaluate the HPLC separation and to determine whether or not
more such separations are needed. When the IR data are combined with NMR
data even more information can be obtained. Combining IR and NMR with good
separation techniques and subsequently with GC-MS and GC-IR, utilizes the most
powerful tools available for organic compound identification.
Fourier Trar.sform Infrared Spectroscopy—
Fourieir Transform infrared systems (95) differ from conventional dis-
persive infrared spectrophotometers in that conventional infrared spectroscopy
uses a monochromator to generate the spectral information whereas an inter-
ferometer is used for this purpose in Fourier Transform infrared spectroscopy.
The use of en interferometer to generate spectral information in the form of
an interferegram (light intensity versus time) necessitates a second differ-
ence between the two types of infrared spectroscopy. This difference is that
FT-IR systens use a dedicated digital computer to obtain the Fourier Trans-
form of the interferogram, converting it to a conventional infrared spectrum
(light intensity versus wavelength or frequency). These two differences lead
to the following two major advantages of FT-IR over conventional infrared
spectroscopy:
• Using an interferometer results in a substantial gain
in energy or light throughput as compared to a mono-
chromotor. This gain in energy results from the elim-
ination of the dispersive device since all wavelengths of
light are examined simultaneously in an interferometer and
no energy is lost (as in a dispersive instrument by
examining the light one wavelength at a time). This
additional energy can be used in one of several ways:
(a) for faster scan speeds (as fast as 0.6 sec), (b) for
up to a 30-fold increase in signal-to-noise ratio, and
(c) for 1Q2-103 greater sensitivity.
• The availability of a dedicated computer offers several
major data-handling advantages. Not only can spectra be
ratioed against each other to remove absorption bands due
to background materials, but the computer can be used to
perform spectral arithmetic. Thus, spectra can be added
or subtracted from each other and also multiplied or divided.
In this way, the spectra can be adjusted in size, and
unwanted components can be removed from the spectra with-
out the necessity of chemical separation. This ability
22
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to utilize a computer is not unique to Fourier Transform
spectroscopy, i.e., in theory a computer could be attached
to a conventional dispersive infrared spectrophotometer .
However, in practice, this is rarely done, whereas all
Fourier Transform systems use a computer. Thus, from a
practical standpoint, the use of a computer is a major
advantage in FT-IR systems.
Nuclear Magnetic Resonance Spectroscopy
NMR as a Screening Technique —
Nuclear magnetic resonance spectroscopy (NMR) is a powerful screening
technique for mixtures of organic compounds. Although not used extensively
in the past for analysis of mixtures, recent progress in instrumentation to
improve resolution, stability, and sensitivity has made the observation of
components of a mixture practical. The types and relative amounts of
various functional groups in the mixture can be determined, and types of
hydrocarbons can be identified. As a screening technique, NMR not only
characterizes the general nature of the fraction, but also provides suffi-
cient information to determine the types of further separations required.
The presence of various functional groups and identification of the
types of hydrocarbons is determined from the chemical shift of peaks in the
spectrum. This is due to the fundamental principle of NMR that the same
nucleus in a different chemical environment resonates at a different
frequency. A comprehensive listing of chemical shifts for protons and for
other nuclei as well as a general review of NMR in the analysis of organic
compounds is available from a number of sources (96-100) .
The recent advances in instrumentation have extended NMR such that less
abundant nuclei can now be routinely observed. The greatest growth has been
in l^c NMR. Carbon is of extreme importance due to its fundamental role in
the structure of organic compounds. The carbon backbone of a compound and
nonprotonated functional groups containing carbon, such as carbonyls or
nitriles, can now be observed directly. Proton NMR and ^C NMR together
cover almost all organic compounds, making the combined methods a powerful
screening technique for mixtures of organic components. l^C NMR has an
additional advantage over proton NMR. Since the shift range for carbon is
600 ppm compared to less than 20 ppm for proton nuclei, there is an enhance-
ment in effective resolution. Broad envelopes of overlapping peaks in
proton NMR may many times be resolved into individual carbon resonances .
This allows for ready identification of specific functional groups. For a
review and further discussion of ^C NMR see References 101-105.
The preliminary limitation of NMR is sample size. For conventional
continuous wave (CW) NMR, milligram quantities are needed for proton NMR,
and natural abundance ^C NMR is essentially impossible. This has largely
been overcome by the use of Fourier Transform NMR. Unlike CW NMR, which
slowly sweeps the radio frequency (RF) applied in a fixed magnetic field,
Fourier Transform (FT) methods used short bursts of RF power at a discrete
frequency for rapid data acquisition. The observation of spectra is made
after the RF power is turned off. In this mode, data are generated as free
induction decay patterns (signal intensity versus time) . This multi-
channel excitation and detection results in a hundredfold improvement in
23
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sensitivity. For proton NMR in the pulse Fourier Transform mode, a practical
minimum is 13 yg of sample. For l^C NMR, milligram quantities are required.
Spectra of smaller amounts may be obtained by using microtechniques. The
availability of a dedicated computer also provides the opportunity for data
handling suc'.i as spectral arithmetic. The spectra can be adjusted in size
and unwanted components can be removed by subtraction without the necessity
of chemical reparation. For a detailed discussion of FT-NMR, see Reference
105.
Evaluation of Screening Data
Determination of the complexity of a given HPLC fraction by the above-
mentioned spectroscopic screening techniques leads to a decision-making point
regarding whether the next step should be further separation, identification
and quantification, or discard the sample due to lack of compound presence.
If the sample is of sufficient complexity or of mixed classes, further
HPLC separations, as discussed subsequently must be performed prior to identi-
fication and quantification. Such a step would result in a recycling of the
samples through HPLC separation and spectroscopic screening techniques until
one class, a simple mixture of classes or a single component, suitable for
identification and quantification, can be isolated.
If the screening procedures show the presence of only one class of
compounds, a very simple mixture, or a single component, specific identifi-
cation and quantification by one of the techniques discussed subsequently
can be perfonned immediately.
In the c.ase of a simple effluent sample mixture, several of the HPLC
class separation samples may not contain any compounds. If spectroscopic
screening procedures show a blank sample, then the fraction should be thus
noted and the: sample discarded without further analysis.
IDENTIFICATION AND QUANTIFICATION
Gas ChromatQfrraphy (GC), and High Performance Liquid Chromatography (HPLC)
Introduction —
Gas chromatography is a powerful tool for separations of complex organic
mixtures. Ir combination with selective detectors, particularly mass
spectrometry, it is among the most powerful instruments available to the
analyst. The principles of HPLC have been extensively discussed earlier,
and thus only limited additional comments on its role in quantitative analy-
sis will be made in this chapter.
A number of gas chromatographs are commercially available which are
suitable for complex organic mixtures. It is important that the column oven
is programmable at various rates up to about 400 C. The facility for dual
columns and dual detectors is sometimes useful, especially when column
effluent is ssplit between two detectors such as a general purpose flame
ionization datector (FID) and specific detectors such as a flame photo-
metric deteclior (FPD) or electron capture detector (ECD) .
24
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The most important part of a gas chromatograph is the chromatographic
column. There are various types of column ranging from packed, through
support coated open tubular (SCOT), to high resolution capillary columns.
Column packings include silica gel, alumina and polymers such as the Poropak
and Chromosorb series, but the coated diatomaceous earth type are very
commonly used. There are a great number of column packings commercially
available;, many of these have been developed in response to specific problems,
whereas others have a more general usefulness. The listing given below in
Table 1 does not pretend to be a complete inventory of column packings and
coatings, but is presented to serve as a preliminary guide. Useful data may
be frequently found in chromatographic supply manufacturers catalogues, in
addition.
A significant proportion of GC separations may frequently be achieved
using conventional packed columns. Capillary columns are becoming more wide-
spread but their use requires greater skill than packed columns. The use of
capillary columns in the analytical strategy presented here will be restricted
to the separation of isomers and other groups of similar compounds, since
many of the difficult separations will already have been accomplished by
means of quantitative HPLC, which has been described earlier.
Gas chromatography can frequently provide good resolution of complex
mixtures of organic compounds, and for this reason it is commonly used in
organic analysis. An obvious limitation of the technique is that involatile
materials are not amenable to this method of analysis. Involatile materials
are most expediently analyzed by liquid chromatography, as described earlier.
A typical organic extract should normally be concentrated to a few
hundred microliters, before subjecting one or two microliters to GC analysis.
When an extract has been separated by HPLC, it is usual to concentrate this
extract to about fifty to a hundred microliters prior to GC analysis. The
choice of solvent for GC is not generally critical; commonly used solvents
such as methylene chloride, acetone, or benzene generally elute significantly
before any of the compounds of interest. If interference between solvent and
sample peaks is observed it may be necessary to change solvents or GC columns.
The sensitivity of GC with conventional FID depends to a large extent
upon peak sharpness and the level of noise or other interfering peaks. In
the absence of appreciable interference, a sensitivity of 50 ng/yl may be
reasonably obtained for hydrocarbons using FID. With FPD or ECD, for sulfur
compounds or chlorinated pesticides for example, a sensitivity or between one
and two orders of magnitude better than this is reasonably obtainable in most
instances.
Quantification with GC and HPLC—
Gas chromatography is probably the most commonly used tool for quanti-
fication in organic analysis. High performance liquid chromatography has
recently been used more extensively for quantification on account of signi-
ficant improvements in instrumentation. In order to carry out quantitative
analysis by either GC or HPLC, it is necessary that the compounds of interest
should be reasonably well resolved from other peaks in the chromatogram.
Furthermore, it is highly desirable that pure samples of the compounds sought
25
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TABLE 1. ORGANIC SPECIES SEPARABLE BY VARIOUS GC COLUMN TYPES
ggmpound Type
Acids f-C
Alcohols
Crci8
Polyalcohols
Aldehydes C,
C5"C18
Amines
Anides
Esters
Ethers
Freons
Glycols
Halides
Hydrocarbons
Aromatic
Olefins C,-
POM
Ketones
Pesticides
Phenols
Column Type
Chromosorb 101
FFAP
Poropak Q, Chromosorb 101
Silar 5CP, Carbowax 20M, FFAP
FFAP
Poropak N, DC-550, Ethofat
Carbowax 20M, Silar 5CP
Poropak Q/PEI, Poropak R
Chromosorb 103, Pennwalt 223
Versamid 900, Igepal CO-630
Poropak Q, Dinonylphthalate
Chromosorb 101 or 102
Carbowax 20M, Silar 5CP
Poropak Q, Chromosorb 102
Chromosorb 107
OV-210, FFAP
OV-101, SE-30
Silar 5CP, Carbowax 20M
DC-550, DC-703
Dexsil 300, OV-101, SE-30
Poropak Q, Chromosorb 102, FFAP
OV-101, OV-225, OV-1, OV-17, SE-30
OV-17S Silar 5CP, Carbowax 20M
26
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should be available; if the components sought are not available, an approxi-
mation may be made through use of their analogues. An internal standard, or
standards, must be chosen which will elute reasonably close to the peak(s)
of interest, and will itself be free from interference from other chromato-
graphic peaks.
Calibration is carried out by preparing a known mixture of internal
standard(s) and compounds of interest, and obtaining a chromatogram for
several different amounts of the mixture. The response factor for each peak
may be determined by measuring height, area, or preferably by use of an auto-
matic integrator or computer integration routine. Sufficient calibration
chromatograms are run until a consistent response ratio between the internal
standard(s) and the chromatographic peaks of interest is obtained. When
response ratios between every compound of interest and an internal standard
have been satisfactorily determined, the appropriate internal standards are
added to the unknown mixture in amounts which are estimated to be of the same
order of magnitude as the peaks which are being determined. GC analysis of
the complex mixture plus internal standards is now carried out using the
same chromatographic conditions at which the response ratios were originally
obtained; from the response factors for the compounds sought in the complex
mixture, and for the known amounts of internal standards together with the
previously determined response ratios, the absolute quantity of each of the
compounds sought in the complex mixture may be readily determined.
When the use of specific detectors, such as GC-ECD for halogenated
pesticides, GC-FPD (sulfur specific filter) for sulfur compounds, or HPLC-
fluorescence for POM compounds, quantification without obtaining good peak
resolution on the chromatogram is often possible. This may be feasible
because the sensitivity of the specific detector is very low for all but the
compounds of interest, which permits previously interfering peaks to be
neglected on the specific detector chromatogram.
The internal standards chosen for GC and HPLC quantification are
usually similar in nature to the compounds which they are being used to
determine, although this is not always mandatory. For example when carrying
out GC quantification of POM species in combustion emissions an uncommon
alkylated or phenylated POM compound is often chosen as an internal standard;
it is of course important that the standard chosen does not occur in the
complex mixture under analysis. In the GC analysis of Ci2 to ^26 hydro-
carbons from an oil-spill sample, it is not uncommon to add an absent C32
hydrocarbon to serve as internal standard for the mixture. When the highest
accuracy is not sought, it is an accepted practice to assume that the
chromatographic response for each member of a class of compounds is the same.
Thus the POM compound 9-phenylanthracene could be used as an internal
standard for all other POM compounds, each being assumed to have the same
response as the internal standard, and the response ratio of each compound to
the internal standard equal to unity.
The accuracy and reproducibility of GC and HPLC quantification using
internal standards is generally better than +10%. The reproducibility may
be readily determined while obtaining the response ratio calibration for
each compound sought.
27
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Gas Chromatographic-Mass Spectrometric Analysis (GC-MS)
Gas chromatographic-mass spectrometry is presently a widely used and
powerful tODl for organic analysis. Common practice is to interface a GC-MS
system with a dedicated mini-computer, and a variety of output units such as
a CRT teletype, or XY plotter, and a high-speed line printer. The GC-MS
analysis contemplated in this report could not be accomplished without an
interfaced nini-computer.
Electron Impact and Chemical lonization—
Mass Spectra may be obtained by electron impact ionization (El) or by
chemical ionization (CI) ; in the latter mode, sample ionization is accom-
plished by neans of an ionized reagent gas. In CI GC-MS analysis, the
reagent gas, such as methane or isobutane, is most commonly introduced through
its use as the GC carrier gas, no molecular separator being used at the
interface between the GC and MS. The MS source pressure for CI with methane,
for example, is typically as high as 600 microns, and thus the far higher
concentration of methane than sample in the source ensures that sample
ionization will occur exclusively by collision with ionized methane.
Chemical ionization results in a rather different mass spectrum to electron
impact in view of its being a much lower energy process; CI spectra are
characterized by less extensive fragmentation of the molecular ion, and the
fragmentation which occurs generally proceeds through loss of neutral
molecules anc: appreciably more stable fragments than is the case with El.
(106) It is usual to observe a protonated molecular ion in CI and this is
frequently accompanied by two adduct ions at M+29 and M+41, in the case of
methane CI, caused by the addition of C2H5 radicals in the source of the mass
spectrometer. Such adduct ions are generally diagnostic for the protonated
molecular ion, and thus it is frequently possible to quickly assign a mole-
cular weight during CI GC-MS analysis.
Since CI analysis is still relatively new, El analysis maintains a
significant advantage which is well suited to the analysis of complex organic
mixtures. Ovsr the past few years extensive data files of El spectra have
been built up, many of these give particular emphasis to toxid and hazardous
substances. As yet, no comparable files exist for CI spectra. Data files
of 40,000 or more El spectra with which to carry out spectral matching as an
aid to identifying unknown compounds are common. Spectral matching is often
carried out by gaining access to spectral files in a central computer, with
several laboratories sharing the same data file. In our experience, a very
convenient method is to store a spectral matching data file on disk, and by
means of a dm.2. disk drive assembly interfaced with the GC-MS mini-computer
it is then possible to carry out instantaneous spectral matching in the
GC-MS laboratory. In any case, spectral matching is a very useful aid to the
interpretation of known DI mass spectra, although it will often fail to
suggest an immediately satisfactory spectral fit. Spectral matching often
provides a useful guide which when coupled with other analytical data, such
as a molecular weight from a CI mass spectrum, liquid chromatography
separation data, and NMR and IR screening studies; correlation of such com-
bined data can frequently lead to a reasonable interpretation of the mass
spectrum.
28
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Correlation with Separation and Screening Data—
GC-MS analysis does of course presuppose that the complex mixture subject
to analysis is capable of separation by gas chromatography and an obvious
limitation is compounds which are too polar to be satisfactorily separated by
GC. Such compounds may be routinely analyzed by HPLC, as discussed earlier.
A great deal of valuable data on an unknown sample will be obtained by
screening studies even before GC-MS analysis is attempted, and the complexity
of the mixture will have been significantly reduced by the HPLC separation
scheme which has been discussed previously.
HPLC will initially be used to separate a complex mixture into three to
five fractions by GPC on the basis of molecular weight, and then each of
these size fractions will be separated into as many fractions as appears
desirable by silica gel or reverse phase HPLC in order to provide relatively
simple mixtures for the subsequent stages of analysis. Following the complete
HPLC separations, probably into about 20 fractions, screening studies using
IR, NMR, and GC will have been carried out as appears appropriate.
Each fraction of the complex mixture of a given molecular weight range
will be separated by HPLC on the basis of polarity into a number of well
resolved fractions. The very nonpolar fractions will consist of aliphatic
hydrocarbons and will not be subject to GC-MS analysis, since these species
are more efficiently analyzes by GC alone. The most polar fractions from the
HPLC separation scheme will be unsuitable for GC separation on account of
their high polarity and involatility, and will be characterized by further
HPLC separation together with IR, NMR, and low resolution MS as required.
However, the HPLC fractions in between these two extremes will range from
nonpolar POM species to polar polyfunctional compounds, and these will be
identified by GC-MS (and possibly GC-IR) preceeded by extensive screening
of each HPLC fraction by the other analytical techniques as discussed
earlier.
Whether CI or El mass spectra, or both, are obtained will depend to a
large extent on the information available from the preliminary screening and
HPLC separation data. For fractions containing the POM species, there is
little point in obtaining both El and CI spectra, since fragmentation is
almost negligible and uniformative in both cases. However, the preliminary
screening data will make it clear that POM species are present, and CI mass
spectra will provide molecular weights which when coupled with chromatographic
data will permit unambiguous compound identification.
For HPLC fractions containing monofunctional compounds, such as aldehydes
and phenols, CI mass spectra may frequently provide sufficient screening
analysis. For example, if an HPLC fraction is known from screening to con-
tain primarily aromatic aldehydres, it should be relatively straightforward
to assign benzaldehyde, tolualdehydes, and higher alkyl benzaldehydes from
the CI spectra, since the only prominent fragmentation will be loss of 28
mass units for CO, to leave the carbon skeleton. The mass spectra are
unlikely to give guidance regarding isomers, but this information may be
inferred from chromatographic data, or possible GC-IR data.
For HPLC fractions which contain polyfunctional compounds, or a mixture
of compounds of different functionality, the most expedient approach in
29
-------
GC-MS analysis would be to initially run El spectra, and initially rely upon
spectral matching, and fragmentation interpretation, to suggest some possible
structures f Dr the compounds present. The available screening data will
greatly assist in narrowing the choice from the list of spectral matches.
It may not ai this stage be possible to make a good assignment of some of the
compounds present, and it would probably be most helpful to additionally
obtain CI maiss spectra. The CI spectra would further narrow the possibilities
by providing a probably molecular weight for the compounds of interest, and
the CI fragmentation may give further valuable data neces9ary to arrive at a
structural assignment. CI fragmentation for moderately polar species can be
rather more informative than for less polar compounds, since the greater
charge separation in the molecule may be more likely to promote fragmentation;
for the same reason, El fragmentation of very polar species may often be too
extreme to be of much value.
GC-MS Data Analysis —
The basic routines available with all commercial mini-computers for
GC-MS are °RI5C* (reconstructed gas chromatogram) and a mass spectrum printing
routine. Modifications of the RGC routine are invaluable for the location of
minor chronaa'iographic peaks. The normal RGC plot consists of a reconstructed
chromatogram which contains ions of all mass numbers, see for example the
'total ion chromatogram' in Figure 4. In order to locate the GC peak for a
compound whoise mass spectrum is known, RGC plots containing prominent ions
in the mass spectrum of this compound may be made. These RGC's should be
overlaid upon the original total ion RGC, maxima in the RGC specific ion
overlays will occur at the spectrum number corresponding to the compound of
interest in ':he total ion RGC.
For example, Figure 4 shows a portion of the GC-MS analysis of residual
oil combustion effluents. In this case, the sample extract was subjected to
liquid chromatography on silica gel to isolate the hydrocarbon and POM
species. Several individual ion overlays are shown superimposed upon the
total ion chromatogram. The 253 ion overlay shows maxima at spectrum numbers
166 and 179, although it is apparent that no peaks are visible on the original
total ion ch;romatogram. If the spectra at spectrum numbers 166 and 179 are
displayed or printed out, it is evident that these two peaks are benz-
fluoranthene or benzpyrene isomers; the spectra are both characterized by a
base peak at m/e = 253 (M+l) and adduct ions (M+29, M+41) at m/e = 281 and
m/e = 293 as shown in Figures 5 and 6. In practice, spectrum 167 minus
spectrum 162, and spectrum 179 minus spectrum 169 would be displayed in order
to subtract any spurious background ion peaks due to column bleed, and the
tailing from other chromatographic peaks. The presence of the compound
sought should be confirmed by printing out its mass spectrum in this manner,
since spurious 'hits' sometime occur due to interfering fragments from other
compounds.
GC-MS Quantification (Specific Ion Monitoring)—
GC-MS analysis offers a highly selective and sensitive mechanism for the
quantification of compounds which have been identified on a complex mixture
(107). Quantisation of an identified material of interest may be expediently
carried out by measurement of one or more characteristic ions in the mass
spectrum of ;he material. From the standpoint of both sensitivity and
30
-------
TOTAL ION
CHROMATOGRAM
203 ION
OVERLAY
253 ION
OVERLAY
331 ION
OVERLAY
23 33 10 SO 63 73 83 33 133 113 123 133
153 163 173 183 133 23C
SPECTRUM NUMBER
FIGURE 4. RECONSTRUCTED ION CHROMATOGRAMS OF RESIDUAL
OIL COMBUSTION EFFLUENTS
-------
SPECTRUM 167-162
IQ
ID
D
OF
OIL COMBUSTIOM EFFLUENTS
(M + 1)
(M + 29)
(M + 41)
nrrjTmjTT»TJTrTTTJTYTVjJTT»|n'"|»»TT|>'r«'JTTTTjrTTTJ
230 2K3 2S0 260 270 280 29(5 333 350
H/E
FIGURE 5. MASS SPECTRUM OF BENZFLUORANTHENES
32
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SPECTRUM 179-169
8
8.
LO -
R.
GC-MS (CH4) OF RESIDUAL OIL COMBUSTION EFFLUENTS
(M + 1}
(M + 29)
. (M + 41)
230 2K5 2SO 260 270 290 230 300 310
M/E
FIGURE 6. MASS SPECTRUM OF BEN2PYRENES
33
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selectivity, It is frequently an advantage to use chemical ionization,
described earlier, in view of the far less extensive fragmentation of the
molecular iori which results in a more intense ion (or ions) at high mass
number.
Following selection of appropriate characteristic ions in the mass
spectrum of l:he compound of interest, an internal standard must be selected.
Ideally, the internal standard should be a deuterium labelled analogue, with
a molecular weight at least three mass numbers greater than the sought
species. However, in the case of complex environmental mixtures this is
frequently itipractical, and an isomer or other structurally similar compounds
may be used. The choice of internal standards for GC-MS quantification is
more exacting than for GC quantification, since not only do we require a
compound which elutes conveniently near to the compound(s) to be measured,
and is not il:self present in order to obviate interferences from fragment
ions of other materials.
Up to e:.ght ions may ordinarily be measured during a quantitative
specific ion monitoring (SIM) GC-MS analysis, although that number may be
significantly increased by use of a computer program which permits changing
the monitored ions at specific time intervals. Thus when the first set of
sought compounds have eluted from the GC column, a second set of ions may be
monitored; this technique is referred to as 'sequential SIM'. For the latter
purpose, and for accurate location of qualitatively identified species in
the mass chromatogram, it is highly desirable that the computer should be
equipped with a real-time programmable clock. Quantification of the compounds
of interest :ls subsequently achieved by ratioing the measured ion current of
the sought compound to that of the internal standard, by applying a previously
determined calibration factor, which allows for any differences in ionization
efficiencies of this compound and the internal standard.
The sensitivity for SIM GC-MS quantification, and for GC-MS analysis in
general, will always depend upon the nature of compounds being studies. For
a compound such as an aliphatic dialdehyde with extensive fragmentation, and
whose mass spectrum is necessarily weak, a sensitivity of 100 ng/ul can
routinely be obtained, sensitivities of an order of magnitude or more higher
than this may be obtained if mass spectrometer conditions are optimized.
One of :he most useful analytical routines is spectral matching, as
previously mentioned. We consider that it is preferable to use a dual disk
drive whereby the bank of reference spectra are stored on a separate disk
which is readily accessible during mass spectral analysis. Ideally, the RGC
of a fraction from HPLC separation should be displayed on the CRT, and a
queue of mass spectra corresponding to RGC peaks should be stored in the
computer memary by command from the teletype. When the queue is established,
the matching routine may be activated and a chosen number of compound
matches (wita correlation coefficients) for each RGC peak may be printed by
a high-speed line printer.
Gas Chromatographic-Infrared Spectroscopic Analysis
While infrared spectroscopy (IR) is the most widely used analytical tool
34
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for the identification of organic compounds, it has given way to mass
spectrometry (MS) for the identification of organic compounds in vaporizable,
complex mixtures. The reason for this was that the characteristics of mass
spectrometry were well suited to coupling with a gas chromatograph (GC) so
that GC could be used to separate the mixture and MS used to identify the
separated compounds. The sensitivity and speed of MS was such that this could
be done "on-line" or "on-the-fly". GC-IR studies used to require trapping and
collection of each GC peak, and not only was this time consuming, but often
there was not enough material available for this purpose.
With the advent of Fourier Transform infrared systems (FT-IR), "on-line"
GC-IR became a reality. The extra energy throughput of the interferometer
of the FT-IR system could be used to give complete infrared scans in as little
as 0.5 sec. Thus, scanning speed was certainly fast enough for "on-line"
GC-IR without the necessity for trapping and collection of the GC peaks.
While the sensitivity level is not as low as desired, it is adequate for many
samples. In addition designs are available for modifying the infrared light
pipe used for GC-IR and this coupled with the use of a liquid nitrogen cooled
infrared detector has been demonstrated to lower the sensitivity to 400
nanograms per GC peak. This sensitivity range makes it possible to obtain
infrared spectra "on-the-fly" of most gas chromatographic peaks. Not only
would such modifications be fairly easy to make, but a complete unit incor-
porating these changes should soon be commercially available.
Thus, GC-IR joins GC-MS as a routinely used instrument for the analysis
of complex mixtures and will be an invaluable analytical tool for identifi-
cation of the components separated by gas chromatography. It is important
to appreciate that GC-MS and GC-IR techniques frequently complement each
other. Since the bases for GC-MS and GC-IR identifications are fundamentally
different, analyses using both techniques will provide substantially more
compound identification data than either technique used independently.
Since the GC-IR system is fully automated, the sample is merely injected
into the gas chromatograph and the FT-IR computer automatically scans,
collects, and stores the interferogram for each GC peak. The operator then
has to manually instruct the computer to plot out each spectrum. Identifi-
cation is made by standard infrared procedures, that of matching the unknown
spectrum with a reference spectrum from available reference libraries of up
to 150,000 spectra. This can be aided by computer search systems. When an
exact match (with a reference spectrum) cannot be found, the functional group
information (available from the IR spectrum) can often be coupled with the
MS data to uniquely identify an unknown compound.
35
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SECTION 5
SAMPLING METHODOLOGY
INTRODUCTION
Sampling is perhaps the most critical stage in the measurement of
hazardous organic species in stack gases; in the absence of a reproducible
and quantitative sampling procedure, sophisticated and sensitive analytical
procedures are of no value. The objective of this chapter is to examine the
parameters necessary for the efficient collection of organic materials from
stack gases.
There are several fundamental requirements of any sampling system for
organic materials which are present in stack gases, if the subsequent analyt-
ical data are to be meaningful.
(1) Organic compounds of interest must be quantitatively collected
(2) The integrity of the collected sample must be preserved
(3) The sampling system must be amenable to quantitative
sample recovery in a manner appropriate for subsequent
analysis
(4) The capacity of the sampling system must enable
sufficient sample to be quantitatively collected for
whatever analytical technique is to be applied.
Either through lack of concern, or an inability to overcome technical diffi-
culties, little progress has been made towards the development of a sampling
system which x;ould satisfactorily meet the above requirements.
Among tha earliest collection methods employed were those which made use
of filtration combined with impinger systems. While such techniques may give
efficient collection of particulate, losses of organic vapors would appear to
be inevitable. This feature was highlighted by Stanberg (108), who
made use of a filter, impingers containing xylene, and cold traps, for the
collection of combustion effluents, with special concern for benzo(a)pyrene.
At high filter temperatures (>300 F) significant losses of benzo(a)pyrene
were reported, but at cooler filter temperatures (<95 F) more efficient
collection wais reported. At the higher temperature range a substantial-
portion of the benzo(a)pyrene would be present on the vapor phase, while at
the lower temperature particulate formation would be favored; accordingly,
36
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much of the benzo(a)pyrene would be retained on the filter at low temperatures,
but at the higher temperatures, both filter and the impingers were unable to
effectively trap the vapor.
The most widely used impinger method for the collection of organic
materials from stack gases has been EPA Method 5 (109,110), a technique
designed for the collection of particulate material, which was first pub-
lished in the Federal Register in 1971. Unfortunately, Method 5 was never
intended for collection of organics; it has a poor efficiency for collection
of vapors, and sample recovery is at best difficult. Nevertheless, a large
number of organic measurement programs have been carried out on stack gases
using this method; all of the data from these must unfortunately be regarded
as questionable.
A recent program for the development of a method for sampling POMs and
PCBs from combustion effluent led to a modified Method 5 utilizing xylene
impinger cooled with dry ice (4). The prescribed technique for sample
recovery from the impingers and filters extract would preclude accurate
quantification, since this involved evaporation of the sample to dryness
followed by redissolution in xylene. While removal of excess solvent from
a sample extract always presents the risk of sample loss, evaporation of a
sample solution to dryness will lead to significant loss of volatile organic
materials. This sampling system was used on a study of the emissions of PCBs
from incineration of domestic refuse (111); although other experimental
difficulties prevented meaningful data from being obtained, no attempt was
made to validate the sampling system.
Attempts have been made to collect stack gas samples through the
evacuated containers or collapsible bags (112). Such methods will provide
quantitative collection, but one characterized by large sample losses to the
containers' walls. Another major drawback is the small volume of gas
collected in this manner, which would result in very low analytical sensitivity.
REVIEW OF ACCEPTABLE METHODS-RECOMMENDATIONS
Within the last two years, a new concept in stack sampling for organic
materials has come into increasingly common use. A combination of con-
ventional filtration with collection of organic vapors by means of a high
surface area polymeric adsorbent has proved highly efficient for collection
of all but the more volatile organic species. The earliest sampling systems
of this type were modifications of the EPA Method 5 in which the polymeric
adsorbent was located between the heated filter and the conventional impingers.
A typical example is the Battelle Adsorbent Sampling System, the Adsorbent
Sampler of which is shown schematically on Figure 7. The stack gases are
sampled isokinetically by a sampling probe and passed through a heated filter,
as described in EPA Method 5. Immediately after leaving the hot filter, the
emissions pass into the cooling coil (120 x 0.8 cm) of the adsorbent sampler
and then pass through a Pyrex frit and into a cylindrical column of Tenax
adsorbent (7 x 3 cm containing 12 g of Tenax for the Mark I sampler, 8 x 4 cm
containing 25 g of Tenax for the Mark II sampler). The flow rate through
the Mark I adsorbent.sampler is typically 14 1 min~ , with a maximum of about
21 1 min~l (or 0.75 cfm). The Mark II sampler has a maximum flow rate of
37
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FLOW DIRECTION
00
8-MM GLASS
COOLING COIL
GLASS FRITTED
DISC
GLASS WATER
JACKET
FRITTED STAINLESS STEEL DISC
15-MM SOLV-SEAL JO!WT
FIGURE 7. ADSORBENT SAMPLING SYSTEM
-------
about 1.5 cfm. The cooling coil and Tenax adsorbent are maintained at a
constant known temperature by means of a thermostated circulating water bath.
The incoming gases are cooled to maintain adsorbent efficiency; yet, the
adsorbent is maintained above ambient temperature to preclude condensation
of the large quantities of water vapor present in all combustion effluents.
The gases leaving the sampler are drawn through an aqueous impinger, a
Drierite trap, and dry gas meter by a Gast-0522 vacuum pump (as in Method 5
sampling). Thus, essentially, the new adsorbent sampling system consists of
the standard EPA train with the adsorbent sampler located between the filter
and the impingers. With this system, filterable particulate can be determined
from the filter catch and the probe wash according to Method 5, whereas the
organic materials present can be determined from the analysis of the filter-
able particulate and the Adsorbent Sampler catch. The impingers are only
used to cool the stream and protect the dry-gas meter, and their contents are
discarded.
The Battelle Adsorbent Sampler was designed to collect sufficient sample
for organic analysis; quantification of known species from stack gases may
routinely be carried out at the ppt level, or lower, through use of an
appropriate analytical technique. Although originally developed to facilitate
quantitative measurement of POM species, recent laboratory validation studies
have demonstrated that the Battelle Adsorbent Sampler can provide quantita-
tive collection of wide ranges of organic materials including: PCBs, PCNs,
epoxides, nitrosamines, chloralkylethers, lactones, methane sulfonates,
carboxylic acids, and phenols (113). Furthermore, the latter studies have
examined the effect of several important parameters on this sampling system,
including nitrogen oxides, sulfur oxides, water vapor, sampler temperature,
and sample loading; details of this work, which is applicable to other
similar sampling systems, are discussed later.
In view of the apparent success of filtration-adsorbtion sampling systems
for organic materials in stack gases, EPA (IERL-RTP) has recently developed
the Source Assessment Sampling System (SASS) for the collection of particulate
and volatile materials. This sampling system is described in detail in two
recent EPA reports (114,115), but will be summarily included here.
The SASS train consists of a stainless steel probe which enters a
thermostated oven containing three series cyclones and a filter holder. The
cyclones facilitate collection of particulate in the following size fractions:
>10 Mm, 3-10 ym, 1-3 ym; a 142 mm filter collects the less than 1 ym
particulate size fraction. Following the oven containing the cyclones and
filter, volatile organic materials are collected in a sorbent trap containing
XAD-2 resin; a vessel for the collection of any condensate is provided
directly below the XAD-2 trap. After exiting the sorbent trap, the gases
pass through an oxidative impinger system for the collection of volatile
inorganic materials, before exiting the system through a 10-cfm pump and dry-
gas meter. The EPA SASS train has a nominal flow rate of 3-5 cfm. A schemat-
ic diagram of the EPA SASS train is shown in Figure 8.
The EPA SASS train promises to be a particularly effective sampling
system for source assessment studies, in view of the relatively large amount
of material which may be obtained for both chemical analysis and bioassay
39
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CONVECTION
OVEN
FILTER
GAS COOLER
GAS
TEMPERATURE
T.C.
IMP/COOLER
TRACE ELFMENT
COLLECTOR
CONDENSATE
COLLECTOR
DRY GAS METER ORIFICE METER
CENTRALIZED TEMPERATURE
AND PRESSURE READOUT
CONTROL MODULE
r\
10 CFM VACUUM PUMP
FIGURE 8. SOURCE ASSESSMENT SAMPLING SCHEMATIC
-------
studies; it has been proposed that an acceptable sample size for the SASS train
will be 30 scfm (114,115) which is equivalent to approximately 6-8 hours
of sampling. Additionally, the size fractionation of the particulate material
may permit the association of hazardous materials with a particular size range,
which would provide valuable input to emission control strategies.
It should however be borne in mind that as of this report date, the
entire SASS train is relatively untried, and lacks authoritative laboratory
and field validation for collection of hazardous materials of concern.
Validation data and acceptable operating parameters which have been obtained
for the Battelle Adsorbent Sampler (113) will serve as a guide for operation
of SASS XAD-2 sorbent trap until directly applicable data become available.
Very recent studies (116) have demonstrated that the stainless steel
gas cooler and XAD-2 cartridge of the SASS train may cause sample contamina-
tion through interaction with the incoming gas stream. Subsequent field
trials of a prototype pyrex gas cooler and XAD-2 cartridge which is inter-
changeable with other SASS components appears to have obviated this problem.
Preliminary flow rate difficulties with the glass system have been overcome
with the redesign as two separable units; the XAD-2 cartridge now incorporat-
ing two 90 mm glass fitted discs and facility for side-loading of the
adsorbent resin.
Sample Recovery from Filtration-Sorbent Sampling System
All presently acceptable sampling trains for the collection of particu-
late and organic vapor consist of some combination of polymeric adsorbent
traps, heated filters, and heated cyclones. Recovery of collected sample is
achieved by extraction with a suitable solvent; generally applicable methods
are described below.
Filters—
Extraction of filter material should be carried out initially with
methylene chloride followed by a reextraction of the residue and filter with
methyl alcohol in order to ensure that all polar and nonpolar organic material
is efficiently recovered. Extraction may be carried out using a Soxhlet
apparatus for 24 hours, or by ultrasonic agitation of the filter with solvent
in a sealed glass container for 1 hour, followed by conventional filtration
of the shredded filter and insoluble particulate matter. We have found both
methods of extraction to be satisfactory, but support the report (117) that
ultrasonic agitation may be slightly superior.
Cyclones, and Probe Rinse —
Particulate material which has been removed from a cyclone or rinsed
from a probe may be solvent extracted in a similar manner to a filter.
Soxhlet extraction may be carried out in a cellulose thimble plugged with
glass wool, or in a frit-ted, (fine) glass thimble with a glass wool plug.
Ultrasonic extraction of particulate may be carried out by agitation with
solvent in a sealed glass container followed by conventional filtration to
remove the insoluble material.
41
-------
Porous Polymer Adsorbent Traps—
The preferred method of solvent extraction involves continuous solvent
extraction oE the adsorbent for a period of 24 hours (118,119); alternatively,
the contents of the adsorbent trap may be transferred to a cellulose extrac-
tion thimble, and subjected to 24 hours of Soxhlet extraction.
The choice of solvent for extracting a porous polymer adsorbent trap
depends partly upon the nature of the adsorbent. It is important that the
solvent chosen does not affect the adsorbent in any way, yet is still an
effective solvent for the removal of collected material. For porous polymer
adsorbent trips utilizing Tenax, we would recommend extracting with a hydro-
carbon such ,is pentane followed by methyl alcohol. Porous polymer adsorbent
traps containing XAD-2 resin should be extracted by methylene chloride
followed by methyl alcohol. Extensive validation studies have demonstrated
that Tenax iis unaffected by extraction with the above solvents (113). Such
validation studies are presently lacking for XAD-2, although preliminary
solvent interaction experiments have demonstrated that the resin has
negligible solubility in methylene chloride.
Liquids—
Aqueous solutions may be solvent extracted by means of conventional
liquid-liquid extraction in a separatory funnel; methylene chloride will
frequently prove to be a suitable solvent. Alternatively when the organic
compounds sought are believed to have a reasonable vapor pressure (most
compounds except the very polar), vapor displacement and adsorbtion may be
used. Inert gas is bubbled through the liquid, and is then passed through a
trap containing chromatographic adsorbent where the volatilized vapors are
trapped (120). Sample recovery from the adsorbent may be made by extracting
it with a suitable solvent, as discussed previously.
A further aqueous extraction procedure involves percolating the solution
through a column of chromatographic adsorbent or resin (121), again followed
by solvent extraction of elution of the solid to recover the organic sample.
Organic oils should not be extracted but should be directly subjected
to high perfDrmance liquid chromatography.
Preparation of Extracts for Analysis—
The man:ier in which the various sample extracts are combined depends
upon the information that is required from the emission source. It is
possible tha: particulate and vapor may need to be analyzed separately on
account of d.ita required for an emission control strategy, for example. In
any case, each extract or combination of extracts should be reduced to a
volume of 0..5 ml or less by a Kuderna-Danish exaporator, the sample is then
ready for direct analysis or separation into fractions by high performance
liquid chromatography. While it is true that some of the more volatile
species may je partly lost during this procedure, the sampling techniques
utilized for organic materials from process streams are generally not
effective for the most volatile species in any case. Much of the sample loss
is likely to be volatile hydrocarbons, which are separately determined by
on-site chromatographic techniques.
42
-------
It is usually desirable to add the prerequisite internal standards to
the sample extract before volume reduction and liquid chromatography
separation.(119) However, the analysis of a grossly complex mixture as
envisioned here precludes addition of internal standards until qualitative
analysis has been carried out, since it is impossible to prejudge the nature
of the compounds present. High performance liquid chromatography separation
techniques do however offer the significant advantage of truly quantitative
sample fractionation. This largely obviates the usual necessity of adding
internal standards before sample fractionation, since in the GPC and HPLC
separations, the sample integrity is expected to remain above 90 percent.
Specific procedures have been recommended for both the Battelle
Adsorbent Sampler train and the EPA SASS train; the former procedures are
based upon 2 years of experience in the field, together with two laboratory
validation studies for EPRI (113,119).
Battelle Adsorbent Sampler Train —
Specific sample extraction procedures for this sampling train include
ultrasonic extraction of the quartz fiber filter with methylene chloride,
and continuous extraction of the Tenax adsorbent trap with pentane followed
by methyl alcohol.
Sample extraction from the Adsorbent Sampler is achieved by means of
Soxhlet extraction with pentane followed by methyl alcohol. 100 ml of each
solvent is required to achieve extraction of an Adsorbent Sampler. The
sampling probes and hot filters from the sampling system were subjected to
methylene chloride extraction. Internal standards are added to the combined
extracts from each sampling train prior to volume reduction to approximately
1 ml by rotary evaporation and Kuderna-Danish evaporation.
EPA SASS Train—
A protocol for recovery of organic material from the SASS train has been
developed by EPA (115). A schematic diagram for recovery from each component
of the train is shown in Figures 9 and 10.
Validation of Stack Sampling Systems for Organic Material
Any stack sampling system used for measurement of hazardous organic
materials must initially be evaluated with regard to collection of materials
of concern. There are many variables associated with sampling of stack
gases which may influence the performance of a sampling system including:
Stack temperature
Sampler temperature
Sampling flow rate
Nitrogen oxides
Sulfur oxides
43
-------
I~-OBC AND
NOZZLE
r*w f*l . ^"W r"MJ
RINSE INTO AV.BER
GLASS CONTAINER
i
A F\r\ T/"N l/\ . 1
/-»L^t> I w IV^- B
CYCLONE RINSE
i
"CYCLONE
STEP 1: TAP AND BRUSH
CONTENTS FROM WALLS
AND VANE INTO LOWER
CUP RECEPTACLE
STEP 2: RECONNECT LOWER CUP
RECEPTACLE AND RINSE ADHERED
MATERIAL ON WALLS AND VANE
INTO CUP (CH2CI2 : CH3OH)
REMOVE LOWER CUP
RECEPTACLE AND
TRANSFER CONTENTS
INTO A TARED NALGENE
CONTAINER
REMOVE LOWER CUP RECEPTACLE
AND TRANSFER (CHjClj : CH-jOH)
INTO PROBE RINSE CONTAINER
/COM
i
3INE]—
STEP 1: TAP AND BRUSH CON-
TENTS FROM WALLS INTO
LOWER CUP RECEPTACLE
STEP 2: RECONNECT LOWER CUP
RECEPTACLE AND RINSE ADHERED
MATERIAL WITH CH,CL : CH OH
INTO CUP ^ •* J
STEP 3: RINSE WITH CHjCI^CH-jOH
INTERCONNECT TUBING JOINING
10/. TO 3^ INTO ABOVE CONTAINER
REMOVE LOWER CUP RECEP-
TACLE AND TRANSFER CON-
TENTS INTO A TARED NAL-
GENE CONTAINER
REMOVE LOWER CUP RECEPTACLE
AND TRANSFER CONTENTS INTO
AN AMBER GLASS CONTAINER
COMBINE
ALL RINSES
FOR SHIPPING
AND ANALYSIS
FIGURE 9. SAMPLING HANDLING AND TRANSFER-NOZZLE, PROBE, CYCLONES, AND FILTER
-------
CYCLONE
STEP 1: TAP AND BRUSH
CONTENTS fROM WALLS
INTO LOWER CUP RECEP-
TACLE
STEP ?: RECONNECT LOWER CUP
RECEPTACLE AND RINSE ADHERED
MATERIAL V/ITH CHCl
INTO CUP
:CH.,OH
J
STEP 3: RINSE WITH CH2CI2:C
INTERCONNECT TUBING JOINING
V INTO ABOVE CONTAINER
REMOVE LOV/ER CUP RECEPTACLE
AND TRANSFER CONTENTS INTO
A TARED NALGENE CONTAINER
REMOVE LOWER CUP RECEPTACLE
AND TRANSFER CONTENTS INTO
AN AMBER GLASS CONTAINER
Ui
FILTER
HOUSINC
STEP 1: REMOVE FILTER AND
SEAL IN TARED PETRI DISH
STEP 2: BRUSH PARTICULATE FROM
BOTH HOUSING HALVES INTO A
TARED NALGENE CONTAINER
STEP 3: WITH CH2CI2:CH3OH
RINSE ADHERED PARTICULATE
INTO AMBER GLASS CONTAINER
STEP
WITH CH2CI2:CH3OH
RINSE INTERCONNECT TUBE
JOINING IM TO HOUSING
INTO ABOVE CONTAINER
NOTES: ALLCH2C12:CH3OH
MIXTURES ARE 1:1
ALL BRUSHES MUST HAVE
NYLON BRISTLES
ALL NALGENE CONTAINERS
MUST BE HIGH DENSITY
POLYETHYLENE
FIGURE 9. (Continued)
-------
COMPLETE XAD-2 MODULE
AFTER SAMPLING RUN
STEP NO. 2
REIEASE CLAMP JOINING XAD-2
CARTRIDGE SECTION TO THE UPPER
GAS CONDITIONING SECTION
REA'OVE XAD-2 CARTRIDGE FROM
CARTRIDGE HOLDER. REMOVE FINE
ME:.H SCREEN FROM TOP OF CART-
RID3E. EMPTY RESIN INTO WIDE
MOUTH GLASS AMBER JAR
REPLACE SCREEN ON CARTRIDGE, RE-
INSERT CARTRIDGE INTO MODULE.
JOIN MODULE BACK TOGETHER.
REPLACE CLAMP.
OFEN CONDENSATE RESERVOIR
VALVE AND DRAIN AQUEOUS
CCNDENSATE INTO A 1 LITER
SEI'ARATORY FUNNEL. EXTRACT
wimcH2ci2.
CLOSE CONDENSATE RESERVOIR VALVE
RELEASE UPPER CLAMP AND
LIFT OUT INNER WELL
V/ITH GOTH UNlTIZED WASH LOTTLE
(CH2Ci2:CH3OH) RINSE INNER WELL
SURFACE INTO AND ALONG CON-
DENSER WALL SO THAT RINSE RUNS
DOWN THROUGH THE MODULE AND
INTO CONDENSATE COLI ECTOR
WHEN INNER WELL IS CLEAN,
PLACE TO ONE SIDE
RINSE ENTRANCE TUBE INTO MODULE
INTERIOR. RINSE DOWN THE CONDEN-
SER WALL AND ALLOW SOLVF.NT TO
FLOW DOWN THROUGH THE SYSTEM
AND COLLECT IN CONDENSATE CUP
RELEASE CENTRAL CLAMP AND
SEPARATE THE LOWER SECTION
(XAD-2 AND CONDENSATE CUP)
FROM THE UPPER SECTION (CON-
DENSER)
ACIDIFY ONE HALF
PH LESS THAN 2
THE ENTIRE UPPER SECTION IS NOW
CLEAN.
RINSE THE NOW EMPTY XAD-2 SEC-
TION INTO THE CONDENSATE CU?
RELEASE LOWER CLAMP AND
REMOVE CARTRIDGE SECTION
FROM CONDENSATE CUP
THE CONDENSATE RESERVOIR NOW
CONTAINS ALL RINSES FROM THE
ENTIRE SYSTEM. DRAIN INTO AN
AMBER BOTTLE VIA DRAIN VALVE.
FIGURE 10. SAMPLE HANDLING AND TRANSFER - XAD-2 MODULE
46
-------
Water vapor
Loading of organic materials.
Unless the impact of each of these variables has been evaluated prior to the
utilization of a sampling system in this field, the value of the data sub-
sequently obtained are of doubtful value.
To date, the only reported data for comprehensive validation of a stack
sampling system have been obtained by Battelle's Columbus Laboratories for
the Battelle Adsorbent Sampler, under laboratory simulated stack conditions
(113). In this study, pre-purified air was heated to 400 F, precisely known
quantities of nitric oxide, sulfur dioxide, water vapor, and up to 13
organic compounds were added, and the resultant gases were passed through a
Battelle Adsorbent Sampler. Sample recovery and analysis was accomplished as
described earlier. The specific variables used on this study were chosen to
reflect extremes normally encountered under actual stack sampling, in order
to realistically challenge the sampling system under precisely measurable
conditions. The variables chosen were:
Sulfur dioxide: 200 and 2000 ppm
Nitric oxide: 150, 500, and 1500 ppm
Water vapor: 2, 4, and 8 percent by volume
Sampler temperature: 80, 105, 130, 155, and 180 F
Organic compound level: 10 and 50 y g each.
In order to elucidate the effects, if any, of both individual variables and
combinations of variables, two fractional factorial statistical experimental
designs were selected. The actual organic materials investigated on the study
were selected on the basis of their being representative of hazardous organic
materials which may be encountered on actual field situations; the materials
subject were:
Y-butyrolactone
bis-2-chloroethylether
N-nitrosodiethylamine
Methyl methanesulfonate
Styrene oxide
p-Cresol
Benzoic acid
Terephthalic acid
47
-------
1,2,3,4-Tetrachloronahpthalene
2,2',5,5'-Tetrachlorobiphenyl
Pyrene
Chrysene.
The comprehensive matrix of data obtained for these organic materials as the
sampling parameters were varied and are described subsequently.
Preliminary experiments indicated that the selected organic could be
divided into two groups on the basis of volatility. The more volatile
materials, the first six in the above list, were subsequently validated over
the 80-130 F temperature range in the Mark II Adsorbent Samplers. The less
volatile group, the latter six compounds in the above list, were validated in
the Mark I Adsorbent Sampler over the 130-180 F temperature range.
Of the variables studied in the less volatile group only the organic
compound levul had a statistically significant effect on the recovery, and
only on two of the compounds studied. Recoveries averaged 79 percent at a
level of 50 j. g, and 72 percent at a level of 10 yg. For the more volatile
compound group, relative humidity, sampler temperature, and organic compound
level were studied. Overall, sampler temperature and organic compound level
were statistically significant variables; percentage recoveries were highest
at the lowest: temperatures (80 F) and highest organic compound level (50 yg).
However, there were variations in effects between the different compounds.
Recoveries ware lowest for compounds with the lowest boiling point due to
losses during the concentration step just prior to analysis.
The statistical analysis revealed that of the variables studied in the
less volatile compound group, only compound loading level had a statistically
significant effect on recovery of any of the organic compounds. Even the
loading level, had no statistical effect for chrysens, TCN, and TCB. For
terephthalic acid, recoveries were so low that valid statistical inferences
cannot be drawn. Average recoveries for the various compounds are listed
in Table 2.
For the more volatile components group, statistical evaluation by the
technique of analysis of variance provides the following conclusions. No
methyl methanesulfonate and y~butyroloctane were recovered in the experiments
and hence, were excluded from the table and the statistical analysis.
(1) For the total set of data (i.e., all four compounds)
only sampler temperature and compound loading had a
statistically significant effect on recoveries.
(2) For styrene oxide none of the variables had a sta-
tistically significant effect on recoveries. The
average recovery was 42 percent.
48
-------
TABLE 2. RECOVERIES IN STACK SAMPLER VALIDATION STUDY
Percent Recovery at
Loading
Compound 50 yg 10 yg
Benzoic acid
Terephthalic(a)
Pyrene
Chrysene(b)
TCN^)
TCB(b)
72
1(2)
80
68
77
96
54
6(14)
67
73
69
97
(a)
The recoveries of terephthalic acid were so low
that valid inferences could not be drawn. Re-
covery was zero in half of the experiments. The
value in parenthesis is the average of those
experiments if recovery was not zero.
' The differences in recovery between the two
loading levels is not statistically significant.
(3) For p-cresol, sampler temperature, relative humidity, and
interaction (combined effect) of compound level and
relative humidity had a statistically significant effect
on recoveries. The average recovery of all experiments
was 74 percent. Recoveries were highest at 25 C (108
percent average), and 50 percent relative humidity (95
percent average). The combination of 50 percent relative
humidity and 50 yg loading give the highest recoveries
(102 percent average).
(4) For N-nitrosodiethylamine only relative humidity has
a statistically significant effect on recoveries. The
average recovery of all experiments was 22 percent.
The highest recoveries were obtained at 50 percent
relative humidity (35 percent). Although the effect of
temperature was not statistically significant the recovery
at sampler temperature, 25 C, (30 percent) was higher
than at the higher temperatures.
(5) For chloroethyl ether only compound loading and temperature
had a statistically significant effect on recoveries. The
average recovery was 45 percent. The highest recoveries
were obtained at the 50 yg loading level (62 percent)
and at a sampler temperature of 25 C (67 percent).
49
-------
The results are summarized in Table 3 in which recoveries are listed. The
average for and the level of each variable at which the highest recoveries
were obtained are listed. Those variables which are statistically signifi-
cant are indicated by an asterisk.
TABLE 3. MAXIMUM RECOVERIES FOR SAMPLER VALIDATION
WITH MORE VOLATILE COMPOUNDS(a)
At
Temperature
Styrene oxide
p-Cresol
N-Nitrosod:Lethylamine
Chloroethy;L ether
59
106*
30
67*
(55
(25
(25
(25
C)
C)
O
C)
At
Loading
45
79
25
62*
(50
(50
(50
(50
yg)
yg)
yg)
yg)
At
Percent RH
43
95*
35*
54
(50)
(50)
(50)
(10)
(a)
Asterisked values are .for statistically significant variables.
Some of the low recovery results obtained in these two statistical
studies wera surprising, since for both groups no sampler breakthrough
exceeding approximately 15 percent of the highest organic compound loading
was ever observed in the preliminary studies. This finding strongly suggests
that sample losses are exaggerated in the recovery and handling of samples
from the Adsorbent Sampler. It would appear that there is an urgent need
for research pertaining to the efficient recovery and concentration of solvent
extracts from such sampling devices.
The selection of sorbent for the adsorbent sampling module must also be
considered; pDlymeric adsorbents used for this purpose should have the
following characteristics:
(1) High surface area to permit adsorption of large amounts
of iunbient pollutants.
(2) Satisfactory particle size to minimize pressure drop across
adsorbent bed.
(3) High column efficiency to permit adsorption of contaminants
from a large volume of air.
50
-------
(4) High specificity for adsorption of the contaminants of
interest, and a low degree of adsorption of water vapor
and hydrocarbons which are often present at high levels
relative to other contaminants.
(5) Compatibility with solvents used for sample recovery.
Recent work by Butler and Burke (122), has characterized various porous
polymers as adsorbents in sampling devices in terms of their surface areas
and adsorption efficiencies.
The two adsorbents which are most commonly used in stack sampling
applications are Tenax GC and XAD-2. While most experience has been gained
to date with Tenax GC, there is reason to believe that XAD-2 may ultimately
prove to be the adsorbent of choice. Besides cost considerations, which
favor XAD-2, XAD-2 has greater surface area and thus has a potentially higher
adsorbent capacity (122). The physical characteristics of Tenax and XAD-2
favor XAD-2, since higher flow rates may be attained through XAD-2 than on
equal volume of Tenax. Finally, Tenax has been shown to be readily
depolymerized under certain stack gas sampling conditions (119,123) , and has
been demonstrated to have a significantly higher solvent extraction blank
than XAD-2 (124). Such background contamination may be relatively unimportant
when carrying out analyses for specific compounds, when the blank is often
eliminated by LC or HPLC cleanup procedures. However, for survey analyses
such as Level-1 (90,115) , adsorbent background contamination may create
serious problems, and for this reason Battelle-Columbus Laboratories have
discontinued the use of Tenax in favor of XAD-2 when multi-specie analysis
are to be carried out.
51
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61
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. FiEPORT NO.
IiPA-600/2-77-202
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
MEASUREMENT OF POLYCYCLIC ORGANIC MATERIALS AND OTHER
HAZARDOUS ORGANIC COMPOUNDS IN STACK GASES
State of the Art
5. REPORT DATE
October 1977
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
8. PERFORMING ORGANIZATION REPORT NO.
Peter W. Joruis, JoAnn E. Wilkinson, and
Pau 1 E. Strut)
9. f ERFORMING ORGAN ZATION NAME AND ADDRESS
Battelle Columbus Laboratories
505 King Avenue
Columbus, Oh-'o 43201
10. PROGRAM ELEMENT NO.
1AD712 BA-10 (FY-77)
11. CONTRACT/GRANT NO.
68-02-2457
12 SPONSORING AGENCY NAME AND ADDRESS
Environmental Sciences Research Laboratory-RTP, NC
Office of Research and Development
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
13. TYPE OF REPORT AND PERIOD COVERED
.Interim 10/76 - 1/77
14. SPONSORING AGENCY CODE
EPA/600/09
15 SUPPLEMENTARY NOTES
16. ABSTRACT
This report documents and reviews state-of-the-art methods for the measurement of
polycyclic organic matter (POM) and other hazardous organic materials which are
present in industrial stack emissions. Measurement methods for many hazardous
compounds, sjch as POM and nitrosamines, are presented and, where specific methods
have not been previously reported, the sections dealing with recommended methods
provide usefjl guidance. Individual chapters are devoted to analytical method-
ology and stationary source sampling methodology, although an effective measure-
ment strategy demands input from each protocol. An attempt is made to present a
unified approach to hazardous organic emission measurement so that future studies
may benefit through more realistic intercomparisons and more precise and accurate
measurements.
17.
a.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
* Air pollution
* Organic compounds
* Measuremert
* Flue gases
* Reviews
Polycyclic compounds
13B
07C
21B
05B
Hi. DISTRIBUTION STATEMENT
RELEASE TO PUBLIC
19. SECURITY CLASS (This Report)
UNCLASSIFIED
21. NO. OF PAGES
70
20. SECURITY CLASS (Thispage)
UNCLASSIFIED
22. PRICE
Form 22ZOC1 (9-73)
62
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