STACK SAMPLING METHODS EPA/600/A-96/061
FOR HALOGENS AND HALOGEN ACIDS
Larry D. Johnson
Methods Branch, MD-44
Air Measurements Research Division
National Exposure Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
ABSTRACT
EPA Methods 26 and 26A and Proposed Methods 0050 and 0051 are in widespread use for
collection and quantitation of stationary source emissions of halogens and halogen acids from a variety
of source types. Considerable research has been conducted in evaluation of these methods, but research
information about the methods has not been published in one convenient summary and much of the
technical community is unaware of its existence.
This paper provides historical and scientific background for the EPA sampling methods in use
today, along with some of their strengths and limitations. The primary evaluation studies are
summarized, and publication references are given. The SW-846 Methods Manual versions of the
procedures are compared with the versions from CFR40 part 60. Relatively new research work is
summarized, along with recent changes in the methods, and critical operating factors.
INTRODUCTION
Sampling and quantitation of stack emissions from hazardous waste combustors and from boilers
and industrial furnaces co-firing hazardous waste are required as part of the Resource Conservation and
Recovery Act (RCRA) permitting process. Hydrochloric acid and chlorine are currently regulated, and
consideration is being given to setting requirements for the similar bromine compounds. Hydrochloric
acid emissions from municipal incinerators are regulated under the Clean Air Act and chlorine,
hydrochloric acid, and hydrofluoric acid are listed among the 189 Hazardous Air Pollutants in the Clean
Air Act Amendments of 1990 (CAAA).
EPA's Office of Research and Development has developed and evaluated two variations of the
same sampling and analysis technology for measurement of halogens and halogen acids. The version
using EPA Method 5 sampling hardware and many Method 5 procedures is shown in Figure 1. The
sampling follows Method 5 isokinetic procedures with full stack traverse. HC1 and other halogen acids
are very water soluble, and sampling is often downstream of a scrubber where water droplets may occur.
Because of their likely halogen acid content, the droplets must be collected isokinetically to avoid non-
representative sampling. The isokinetic version of the sampling technology shown in Figure 1
corresponds to EPA Method 26A1 and Proposed EPA Method 00502, which will be described and
discussed more fully later in this paper. A midget impingcr train packaging of the same sampling
technology, which may be used when isokinetic sampling is not required, corresponds to EPA Method
26' and Proposed EPA Method 00512. Considerable research has been conducted in evaluation of these
methods, but research information about the methods has not been published in one convenient summary
and much of the technical community is unaware of its existence. A summary of the more important
studies relative to these methods follows.
The earliest work with a major influence on the EPA methods was reported in 1979 by Cheney
and Fortune3. They investigated collection of HC1 in NaOH solutions of several concentrations followed
by four different titration procedures. A mercuric nitrate titration after collection in 0.1 M NaOH was
ultimately recommended. Cheney and Fortune followed their earlier work with another study reported
in 19844. In the second study, they investigated reaction and sorption losses of HC1 during sampling.
Use of disc filters made of quartz was recommended to minimize losses to the filter material, and

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relatively high flow rates were recommended to minimize interactions with collected alkaline particulate
material.
Stem, et al. presented their work during 1983, and it appeared in print in 19845. They reported
development and laboratory evaluation of a sampling and analysis system for collection and speciation
of halogens and halogen acids. The sampling equipment was essentially the midget impinger version of
that shown in Figure 1, but ion chromatography was chosen for the analysis because of its high
selectivity, low detection limit, and multiple ion capability. Collection and quantitation of HC1 (130
ppm) and Cl2 (19 ppm) were successful in the presence of 250 ppm S02 and 600 ppm NOx. It was
demonstrated that dilute H2S04 was a superior collection medium for the halogen acids as compared to
water. When water was used, some retention of the halogen compounds resulted, presumably from
disproportionation reactions. The presence of the dilute acid suppressed these types of reactions and
resulted in excellent speciation. Poor recovery was obtained with HBr (10 ppm). The authors
speculated that the poor performance for HBr was due to sorption or line losses. The fact that virtually
all of the HBr was collected in the first impinger would be consistent with that hypothesis, and would
rule out poor impinger collection as the problem.
The publications of DeWees, et al.6 and Steinsberger and Margeson7 constitute the principal
evaluation base for measurement of HC1 and Cl2 by Methods 26 and 26 A and Proposed Methods 0050
and 0051. The two publications are both reports of the same body of work. Building on the work of the
previous authors, both laboratory evaluation and field testing were carried out. During the early phases
of the investigation, the nonisokinetic midget impinger train received most of the attention, but the
isokinetic sampler was worked into later experiments. Primary focus was on evaluation of the
methodology for determination of HC1, but Cl2 was studied as a potential interferant, and all indications
were that the method was performing adequately for Cl2 as well.
During the laboratory phase of the project, a ruggedness test was conducted to evaluate the effect
of six variables on HC1 results. Within the ranges tested, the method was shown to be insensitive to low
reagent volume, increased first impinger pH, longer sampling times, elevated impinger temperatures,
higher sampling rate, and elevated Cl2 levels up to 50 ppm. Earlier experiments showed that only a
3.4% positive bias was caused by 197 ppm of CI, in a gas stream containing 221 ppm of HC1.
The methodology was field tested using dynamic spiking of gaseous HC1 standards and a test
protocol similar to that later specified in Method 301, Field Validation of Emission Concentrations from
Stationary Sources. Key conclusions of the field test were: 1. The precision of the method for HC1
ranged from 0.24-0.49 ppm at flue gas HC1 levels of 3.9 to 15.3 ppm. 2. The bias of the method was
<8% for HC1 cylinder gases of 9.7 and 34.3 ppm. 3. The manual method agreed within 7% with a
continuous HC1 monitor based on gas filter correlation infrared spectroscopy (GFC/'IR). 4. Flue gas C02
absorption by alkaline impinger reagents was insignificant with either the midget impinger train or the
Method 5 type train. 5. The midget impinger train and the Method 5 type train showed similar results at
a flue gas HC1 concentration of 21.2 ppm, but the Method 5 type train produced results with a negative
bias of about 50% compared to the midget impinger train and the continuous monitor both of which
averaged 4.8 ppm.
The work of Steger et al.8 was prompted by concern over three potential sources of error in
Proposed Method 0050 and Method 26A. They investigated possible negative bias related to purging of
the optional cyclone catch, negative bias at low ppm concentrations previously reported, and potential
positive bias due to the presence of NH4C1. Key findings were: 1. A negative bias at low HC1
concentrations was confirmed. The bias was variable and seemed to correlate better with gas stream
moisture content than with HC1 concentration. Higher probe and filter temperatures were beneficial. 2.
NH4C1 caused a positive bias under all test conditions by penetration of the filter as a vapor and
subsequent interference in the analysis. Lower probe and filter temperatures were beneficial for this
interference, but detrimental from a sorption standpoint, as described above. 3. When high moisture
levels force the use of the cyclone, a post-sampling cyclone purge is essential to drive any trapped HC1
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into the impinger catch. However, when the volume of aqueous solution in the cyclone exceeded 25
mL, the 45 minute purge required in Method 0050/26A was not sufficient to complete the task.
Powell and Dithrich9 investigated the use of GFC/IR for monitoring of HC1 emissions from
cement kilns, in part duplicating the work of Steinsberger and Margeson7 and confirming the efficacy of
the monitoring technology tested. Method 26 testing conducted simultaneously produced results for
HC1 compared to those from GFC/IR which ranged from being low by a factor of 2 to extremely low by
a factor of 30. In subsequent laboratory studies HC1 was spiked into Method 26 trains with and without
probes and filters present. Recoveries were reasonably quantitative for the impingers-only, but were low
by factors of 3 to 5 for the full train. The authors concluded that the train losses were due to
condensation (sorption?) to train surfaces and to reaction of HC1 with alkaline particulate material
collected on the filter. Any losses which may have been due to these effects were no doubt exacerbated
by the use of fiberglass filter material in direct violation of Method 26, which specifies quartz or
fluorocarbon coated quartz filters.
PRINCIPLES OF OPERATION
EPA Air Test Method 26 and Method 26A are essentially the same as Proposed Method 0051
and Proposed Method 0050, respectively. Methods 26 and 26A have been extended to deal with other
halogens and halogen acids in addition to chlorine and chloride, but the principles of operation are still
the same.
The following description is worded in terms of sampling and analysis of HC1 and Cl2 with
Proposed Method 0050, but it also applies to the other three methods and the other halogens and halogen
acids. Method 0050 contains all of the elements necessary to cope with the usual multiphase mixture
extracted from incinerator stacks. A heated glass or quartz probe and probe nozzle assembly is
followed by a heated filter and a series of liquid filled impingers, which perform the dual role of
cooler/condenser and sample collection medium. The usual gas moving and measuring hardware
follows.
It is a straightforward matter to collect HC1 in either acidic, neutral, or basic solution, and to
analyze for the resultant chloride ion with any one of dozens of determinative analysis techniques. The
situation becomes more complex when the distinction must be made between HC1 and chlorine and
when the stack emissions contain chloride salts which might interfere with the analysis. One of the best
ways to trap chlorine is by the use of dilute sodium hydroxide, but this produces a chloride ion as well as
a hypochlorite ion. This confuses interpretation of the results if HC1 and chlorine are both sampled.
In Proposed Method 0050, the chloride salts are removed from the sample stream by the filter,
while both HC1 and chlorine pass through. Some glass fiber filters have sorbed unacceptable quantities
of HC1, probably due to alkaline impurities on or in the glass surface. The filter specified for Proposed
Method 0050 is a fluorocarbon polymer coated quartz material. Reports of inconsistent operating
behavior of the coated filter have led to approval of quartz filters as an alternative. Uniform and
adequate heating of the probe and the filter is essential when collecting HC1. Any trace of moisture
condensation will result in removal of HC1 from the gas stream, and a resulting low bias in the final data.
This problem becomes even more serious at HC1 concentrations in the low ppm range. Even dry probe
and filter surfaces may sorb HC1 if their temperature is too low. The filter support must be fluorocarbon
polymer rather than fritted glass, since the latter can remove significant amounts of HC1.
If sufficient water is present in the sample stream to wet the filter, it will be necessary to include
the optional cyclone for droplet removal. Inclusion of the cyclone complicates the sample recovery
process later, so it should not be added unless necessary. Wetting of the filter is unacceptable, since it
allows salt migration through the filter and possible contamination of the HC1 collection elements.
Once HCI and chlorine pass through the filter, the HC1 is collected in the dilute sulfuric acid
solution and the chlorine is collected in the dilute sodium hydroxide. The dilute acid prevents capture of
chlorine in the earlier impingers and thus provides for a cleaner separation of the two substances of
3

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interest.
After shipment to the laboratory, the dilute acid from the first three impingers (assuming the
optional impinger is used) is combined and analyzed for chloride ion by ion chromatography using
Method 905610. The BIF Methods Manual specifies analysis of samples from Method 0050 by means of
Draft Method 9057. That method has been discontinued at the draft stage and replaced by Method 9056.
Method 9057 was developed for chloride analysis only, while Method 9056 is effective for all of the
common halide ions, including chloride. The two methods contain very similar ion chromatography
procedures, and should yield the same result for chloride ion. The determinative analytical method
included in Methods 26 and 26A is equivalent if not identical to Method 9056.
Method 9056 offers a far better combination of sensitivity and specificity than any other chloride
method. The chloride from the first three impingers is reported as HC1, using the appropriate equation
from Method 0050. The combined contents of the fourth and fifth impingers is analyzed by Method
9056 and reported as chlorine using the proper equation from Method 0050. The assumption is made
that the chlorine disproportionates in the basic solution to form one chloride ion and one hypochlorite
ion. Reports have been received that reducing agents in the stack gas, perhaps sulfur dioxide, have
collected in the dilute hydroxide along with the chlorine and have ultimately caused reduction of a
portion of the hypochlorite to chloride. If that reduction occurs, the disproportionation stoichiometry no
longer applies, and the calculated result for chlorine is too high, perhaps as much as double the true
concentration. Since no way has been discovered to predict or determine the extent of this problem in a
given sample acquisition, a modification to the methodology was needed.
A simple remedy has been incorporated into methods 26 and 26A, but not yet into Proposed
Methods 0050 and 0051 .The remedy, which performed well in an unpublished laboratory study, is to
add a small amount of sodium thiosulfate to the dilute caustic solution in order to consistently drive the
chlorine reduction product all the way to chloride ion. The equation for calculation of chlorine
concentration in the stack gas is changed to reflect the fact that one chlorine molecule in the stack
sample is represented by two chloride ions in the impinger catch rather than one. One can speculate on
the likelihood of chlorine and a reducing agent such as sulfur dioxide coexisting in the stack in the first
place, but the remedy also protects against gradual reduction of the hypochlorite during sample shipping
and storage. Addition of thiosulfate is expected to be incorporated into Proposed Methods 0050 and
0051 during the promulgation process.
CRITICAL OPERATING ELEMENTS
It is imperative that all elements ahead of the filter be adequately heated in order to prevent
moisture condensation or direct sorption of halogens and halogen acids. The acids are particularly prone
to losses because of their high water solubility. Possible contamination by halide salts prevents rinsing
of front half equipment surfaces to recover deposited material. Steger, et al. recommend running the
train at 200 *C to eliminate the negative bias due to sorption and condensation. Even running the train at
200 "C will not always be sufficient to keep the filter dry if unusually large amounts of water are
present. In such cases the optional cyclone must be employed. It is important that the filter not become
wet enough to allow migration of soluble halide salts through the filter as solutions. Penetration of the
filter in this manner could cause contamination of the impinger catch and subsequent positive bias in the
halogen acid results.
Filter material must be either the designated fluorocarbon coated quartz or plain quartz. Cheney
demonstrated that fiberglass filters sorb unacceptable quantities of HC1, and that fiberglass "plugs" are
even worse. Sieve style filters, as opposed to mat configurations do not adequately filter fine particulate.
Filter support material should also be inert, preferably fluorocarbon. Glass frits apparently do not
always cause problems, but are best avoided.
Continued maintenance of a high pH in the back impingers is a must for adequate collection of
the halogens. This is only a problem in sampling high acidity emissions. Steinsberger and Margeson7
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showed that scrubbing of C02 from combustion gas into 0.1M NaOH is so inefficient that it does not
seriously decrease the pH. The higher concentration NaOH necessary to compensate for higher
quantities of acids in some sources may scrub C02 more efficiently. Data on C02 scrubbing as a
fimction of base concentration, has not been located to date, but will be generated if not found in the near
future. It is considered necessary for a proper understanding of the limitations of the halogen sampling
technology as well as the methods for hexavalent chromium and HCN, all of which depend upon
collection into basic solution. The use of pH indicators in the impingers is currently under investigation
as part of a project to develop a sampling method for HCN. Results will be directly transferable to the
halogen/halogen acid methods. In the meantime it is prudent to check the pH occasionally during
sampling, using pH paper or other means, especially if stack acidity is high.
Careful handling with special concern for minimization of contamination is made even more
important with this methodology than usual, because the analytical finish alone cannot discriminate
between halide ion from halogen/halogen acid and that from ionic salts.
LIMITATIONS AND AREAS OF CONCERN
All methods have limitations and areas of concern. The halogen/halogen acid methods work
well within the ranges of concentrations and variables studied, as well as in numerous cases of field
application. The following discussion should not be construed as critical of the methodology, the
evaluation studies performed in the past, or the quality of the data taken to date with the methods. Many
questions have been answered, but there are still aspects and applications of the methods which could
profit from further research.
Filter Penetration
Any substance which is capable of penetrating the filter and forming chloride ion in the impinger
is a possible source of HC1 interference for Methods 0050,0051,26 and 26A. Fortunately, there are not
many substances that have that capability. Phosgene could certainly interfere, but if a combustor is
emitting phosgene at high enough concentrations to seriously bias the HC1 results, high HC1 results is
probably the least of the operator's problems. There has been considerable discussion whether
ammonium chloride is volatile enough to penetrate the filter as a vapor and to cause a positive bias. It
now appears that it may be possible under certain conditions. If ammonium chloride is thought to be
causing significant bias in HC1 results, an alternative technique, such as an infrared spectrophotometry
based monitor, should be considered. Hypochlorous acid, if present in the stack might be volatile
enough to penetrate the filter, or might decompose on the hot filter to form chlorine. If hypochlorous
acid passed the filter as a vapor, it would be captured by either the acidic impinger solutions or the basic
ones, but the distribution between these collector elements is currently unknown.
One potential penetration mechanism which is sometimes perceived to be a problem, is not
problematic at all. An intact and well installed filter of the type specified will not pass significant
quantities of solid halide salts such as NaCl, CaCl2, and KC1. Filtration efficiency actually increases for
finer particulate matter, after reaching a minimum at about 0.3 micrometers"-12. The presence of undue
amounts of ions such as sodium, potassium, or calcium in the impingers is probably due to
contamination during handling, a broken filter, or operation with a wet filter. Attempts to correct the
halogen acid results by subtracting amounts from the total in proportion to cation concentrations found
in the impinger catch are ultimately unsound and likely to overcorrect. Except in highly artificial
laboratory situations, it is not possible to determine in what form the ionic material entered the impinger
and whether it should be subtracted or not. For example, NH4+ may have entered as NH4C1, but may
equally have passed the filter as NH3. Sodium or potassium contamination may have been in the form of
nitrates, sulfates, or dozens of other salts.
5

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Reactions Between Halides and Halogens
Two unpublished contractor reports to EPA raise interesting questions concerning potential
reactions between halogen acids and halogens during sampling13,14. ETS, Inc. raised preliminary
questions and EER Corp. demonstrated that reactions between halides and halogen could affect the
ultimate speciation of the sample catch. It is not clear, however, whether such a reactive combination
would ever be sampled in a real stack, or whether the "realignment of species" would have occurred
prior to sampling. It would seem more likely that a reactive mix of this nature would be found in an
internal process stream than in flue gas.
Validation Status
As previously discussed, the methodology has been well tested for collection of HC1 up to 500
ppm and as low as a few ppm. The method probably works well at higher concentrations, although the
speciation split may suffer in the presence of high Cl2 levels. Laboratory data for Cl2 collection is
acceptable, but that part of the method has not been field tested with dynamic spiking. EER showed
generally good results for HF in a laboratory study. HBr results have been disappointing, perhaps due to
reactions during the spiking experiments.
Alkaline Particulate
The possibility of low results due to reaction of HC1 with alkaline particulate material collected
on the filter was of great concern to Steinsberger and Margeson7 and has recently resurfaced in the work
of Powell and Dithrich9. The magnitude of this effect has not been conclusively demonstrated, and is
likely variable with particulate composition. Steinsberger and Margeson7 recommended an optional
version of Method 26 with a probe nozzle directed counter to stack flow, in order to reject as much of
the reactive particulate as possible. This arrangement would not be acceptable when isokinetic sampling
is required. Another option would be to employ a GFC/IR monitor, although most monitoring systems
are not capable of isokinetic sampling. Monitors all employ particulate filters which could encounter the
same scrubbing effects as those found in manual methods. Frequent cleaning of the filter by "blow-
back" could help to minimize the problem.
Thiosulfate Interference
A unpublished report to EPA showed that thiosulfate was the best of several reducing agents
tested for addition to the alkaline impinger catch before analysis15. Since the thiosulfate treatment has
been added to Methods 26 and 26A, reports have been received that the thiosulfate can cause
interference in the analysis if present in excess. A good discussion of suggested procedures for the
adjustment of the concentration of the reducing agent is included in a recent newsletter16.
SUMMARY
These methods require care! Given careful operation, they have been shown to work well for
HC1 and chlorine in sampling "normal" stack emissions such as those from incinerators and power
plants. More complicated and more reactive gas mixtures may cause problems which will require
research to overcome. Efficacy of the methods for other halogens and halogen acids has not been as
well evaluated, and the limited data available show mixed results. Good precision and accuracy become
difficult to achieve with these methods at concentrations below approximately 5 ppm. Performance
data at concentrations above 500 ppm HC1 are uncommon
NOTICE
The information in this document has been wholly funded by the United States Environmental
Protection Agency. It has been subjected to Agency review and approved for publication. Mention of
trade names or commercial products does not constitute endorsement or recommendation for use.
6

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Code of Federal Regulations, Title 40, Part 60, Appendix A, U.S. Government Printing Office,
Washington, DC, 1994.
U.S. Environmental Protection Agency, Proposed Methods 0050 and 0051, in SW-846
Manual, Third Update to the 3rd ed., U.S. Government Printing Office, Washington, DC,
Proposed July 25, 1995.
Cheney, J.L. and Fortune, C.R., "Evaluation of A Method for Measuring Hydrochloric Acid in
Combustion Source Emissions," The Science of the Total Environment. 13, pp 9-16,1979.
Cheney, J.L. and Fortune, C.R., "Improvements in the Methodology for Measuring Hydrochloric
Acid in Combustion Source Emissions," J. Environ. Sci. Health A 19(3), pp 337-350, 1984.
Stem, D.A., Myatt, B.A., Lachowski, J.F. and McGregor, K.T., "Speciation of Halogen and
Halide Compounds in Gaseous Emissions," in Incineration and Treatment of Hazardous Waste:
Proceedings of the Ninth Annual Research Symposium, EPA-600/9-84-015, NTIS PB84-234525,
July 1984.
DeWees, W.G., Steinsberger, S.C., Margeson, J.H., Knoll, J.E. and Midgett, M.R., "Laboratory
and Field Evaluation of A Methodology for Measuring HC1 Emissions from Stationary Sources,"
in Proceedings of the 1989 EPA/A WMA International Symposium: Measurement of Toxic and
Related Air Pollutants, Document VIP-13, Air and Waste Management Association, Pittsburgh,
PA, 1989.
Steinsberger, S.C. and Margeson, J.H., Laboratory and Field Evaluation of a Methodology for
Determination of Hydrogen Chloride Emissions from Municipal and Hazardous Waste
Incinerators, EPA/600/3-89/064, NTIS PB89-220586/AS, U.S. Environmental Protection
Agency, Research Triangle Park, NC, August 1989.
Steger, J.L., Wagoner, D.E., Bursey, J.T., Merrill, R.G., Fuerst, R.G. and Johnson, L.D.,
"Laboratory Evaluation of Method 0050 for Hydrogen Chloride," in Proceedings of the 13th
Annual International Incineration Conference, Houston, TX, May 1994, University of California,
Irvine, CA, 1994.
Powell, J.H. and Dithrich, E. C., "Hot-Wet Instrumental Hydrogen Chloride Emissions
Quantification Using GFCIR - Method Validation and Comparison," Presented at Air and Waste
Management Association Conference: Waste Combustion in Boilers and Industrial Furnaces,
Kansas City, MO, March 1996.
U.S. Environmental Protection Agency, Method 9056, in, SW-846 Manual, Second Update to the
3rd ed., U.S. Government Printing Office, Washington, DC, November 1990.
D.B. Harris, U.S. Environmental Protection Agency, Research Triangle Park, NC, personal
communication, 1978.
T.E. Ward, U.S. Environmental Protection Agency, Research Triangle Park, NC, personal
communication, 1994.
Unpublished Report to U.S. Environmental Protection Agency, ETS, Inc., Method 26A Intra lab
Study, 1993.
Unpublished Report to U.S. Environmental Protection Agency, EER Corporation, Evaluation of
the Biases Associated with EPA Reference Method 26A for the Determination of Hydrogen
Chloride Emissions from Stationary Sources, 1995.
Unpublished Report to U.S. Environmental Protection Agency, Radian Corporation, Reduction
of Hypochlorite in the EPA Method 0050 Sampling Train, 1992.
Riley, C.E., "Insight into EPA's Test Methods for Hydrogen Chloride and Chlorine," in The Riley
Report, Triangle Laboratories of RTP, Inc., Research Triangle Park, NC, April 1996,

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Heated
Teflon or Quartz Box
Filter

Heated Probe
Optional
Thermometer
Pitot Tube
Manometer
Silica Gel
0.1N NaOH
0.1 N H2SO4
Calibrated
Orifice
Coarse
Vacuum
Gauge
Inclined
Manometer
Dry Gas Vacuum
Meter Pump
ure 1. Sampling Train for Methods 0050 and 26A.

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TECHNICAL REPORT DATA
1. REPORT NO.
EP A/600/A-9S/061
2.
3.R
4. TITLE AND SUBTITLE
Stack Sampling Methods for Halogens and Halogen Acids
5.REPORT DATE
6.PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
Larry D. Johnson
8.PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
National Exposure Research Lab
Office of Research and Development
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
10.PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
N. A.
12. SPONSORING AGENCY NAME AND ADDRESS
National Exposure Research Lab
Office of Research and Development
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
13.TYPE OF REPORT AND PERIOD COVERED
Symposium Proceedings
Measurement of Toxic and
Related Air Pollutants, RTP
14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
16. ABSTRACT
EPA Methods 26 and 26A and Proposed Methods 0050 and 0051 are in widespread use for
collection and quantitation of stationary source emissions of halogens and halogen acids from a variety
of source types. Considerable research has been conducted in evaluation of these methods, but research
information about the methods has not been published in one convenient summary and much of the
technical community is unaware of its existence.
This paper provides historical and scientific background for the EPA sampling methods in use
today, along with some of their strengths and limitations. The primary evaluation studies are
summarized, and publication references are given. The SW-846 Methods Manual versions of the
procedures are compared with the versions from CFR40 part 60. Relatively new research work is
summarized, along with recent changes in the methods, and critical operating factors.
17. KEY WORDS AND DOCUMENT ANALYSIS
a. DESCRIPTORS
b.IDENTIFIERS/ OPEN ENDED
TERMS
c.COSATI



18. DISTRIBUTION STATEMENT
Release to Public

19. SECURITY CLASS (This
Report)
Unclassified
21.NO. OF PAGES

20. SECURITY CLASS (This
Page)
Unclassified
22. PRICE

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