< * EPA 600/4-81-056
United States
Environmental Protection
Agency
vvEPA Research and
Development
Jgtal Organic Halide
Method 450.1 - Interim
Prepared for
Joseph A. Cotruvo
Director
Criteria and Standards Division
Office of Drinking Water
Prepared by
Stephen Billets, Ph.D.
James J. Uchtenberg
Physical and Chemical Methods Branch
Environmental Monitoring and Support Laboratory
Cincinnati, Ohio 45268
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TOTAL ORGANIC HALIDE
Method 450.1
Interim
U S. Environmental Protection Agency
Office of Research and Development
Environmental Monitoring and Support Laboratory
Physical and Chemical Methods Branch
Cincinnati, Ohio 45268
November 1980
U.S. Environ-,-,-• ; ~ :^:on Agency
Region V, L ;
230 Soul'i 'j ••,'••• -jr
' J • V- ' . •>*• -f tt
Chicago, liii.^-j COo-04
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TOTAL ORGANIC HALIDE
Method 450.1
1. Scope and Application
1.1 This method is to be used for the determination of Total Organic
Hal ides as Cl" by carbon adsorption, and requires that all
samples be run in duplicate. Under conditions of duplicate
analysis, the reliable limit of sensitivity is 5 ug/L. Organic
halides as used in this method are defined as all organic species
containing chlorine, bromine and iodine that are adsorbed by
granular activated carbon under the conditions of the method.
Fluorine containing species are not determined by this method.
1.2 This is a microcoulometric-titration detection method applicable to
the determination of the compound class listed above in drinking
and ground waters, as provided under 40 CFR 265.92.
1.3 Any modification of this method, beyond those expressly permitted,
shall be considered as major modifications subject to application
and approval of alternate test procedures under 40 CFR 260.21.
1.4 This method is restricted to use by, or under the supervision of,
analysts experienced in the operation of a pyrolysis/microcolumeter
and in the interpretation of the results.
2. Summary of Method
2.1 A sample of water that has been protected against the loss of
volatiles by the elimination of headspace in the sampling
container, and is free of undissolved solids, is passed through a
column containing 40 mg of activated carbon. The column is washed
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to remove any trapped inorganic halides, and is then pyrolyzed to
convert the adsorbed organohalides to a titratable species that can
be measured by a microcoulometric detector.
3. Interferences
3.1 Method interferences may be caused by contaminants, reagents,
glassware, and other sample processing hardware. All of these
materials must be routinely demonstrated to be free from
interferences under the conditions of the analysis by running
method blanks.
3.1.1 Glassware must be scrupulously cleaned. Clean all glassware
as soon as possible after use by treating with chromate
cleaning solution. This should be followed by detergent
washing in hot water. Rinse with tap water and distilled
water, drain dry, and heat in a muffle furnace at 400°C
for 15 to 30 minutes. Volumetric ware should not be heated
in a muffle furnace. Glassware should be sealed and stored
in a clean environment after drying and cooling, to prevent
any accumulation of dust or other contaminants.
3.1.2 The use of high purity reagents and gases help to minimize
interference problems.
3.2 Purity of the activated carbon must be verified before use. Only
carbon samples which register less than 1000 ng/40 mg should be
used. The stock of activated carbon should be stored in its
granular form in a glass container with a Teflon seal. Exposure to
the air must be minimized, especially during and after milling and
sieving the activated carbon. No more than a two-week supply
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should be prepared in advance. Protect carbon at all times from
all sources of halogenated organic vapors. Store prepared carbon
and packed columns in glass containers with Teflon seals.
3.3 This method is applicable to samples whose inorganic-halide
concentration does not exceed the organic-halide concentration by
more than 20,000 times.
4. Safety
The toxicity or carcinogenicity of each reagent in this method has not
been precisely defined; however, each chemical compound should be
treated as a potential health hazard. From this viewpoint, exposure to
these chemicals must be reduced to the lowest possible level by whatever
means available. The laboratory is responsible for maintaining a
current-awareness file of OSHA regulations regarding the safe handling
of the chemicals specified in this method. A reference file of
material-handling data sheets should also be made available to all
personnel involved in the chemical analysis.
5. Apparatus and Materials (All specifications are suggested. Catalog
numbers are included for illustration only).
5.1 Sampling equipment, for discrete or composite sampling
5.1.1 Grab-sample bottle - Amber glass, 250-ml, fitted with
Teflon-lined caps. Foil may be substituted for Teflon if
the sample is not corrosive. If amber bottles are not
available, protect samples from light. The container must
be washed and muffled at 400°C before use, to minimize
contamination.
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5.2 Adsorption System
5.2.1 Dohrmann Adsorption Module (AD-2), or equivalent,
pressurized, sample and nitrate-wash reservoirs.
5.2.2 Adsorption columns - pyrex, 5 cm long X 6-mm OD X 2-mm ID.
5.2.3 Granular Activated Carbon (GAC) - Filtrasorb-400,
Calgon-APC, or equivalent, ground or milled, and screened to
a 100/200 mesh range. Upon combustion of 40 mg of GAC, the
apparent-halide background should be 1000-mg Cl"
equivalent or less.
5.2.4 Cerafelt (available from Johns-Manville), or equivalent -
Form this material into plugs using a 2-mrn ID
stainless-steel borer with ejection rod (available from
Dohrmann) to hold 40 mg of GAC in the adsorption columns.
CAUTION: Do not touch this material with your fingers.
5.2.5 Column holders (available from Dohrman).
5.2.6 Volumetric flasks - 100-mL, 50-mL.
A general schematic of the adsorption system is shown in
Figure 1.
5.3 Dohrmann microcoulometric-titration system (MCTS-20 or DX-20), or
equivalent, containing the following components:
5.3.1 Boat sampler.
5.3.2 Pyrolysis furnace.
5.3.3 Microcoulometer with integrator.
5.3.4 Titration cell.
A general description of the analytical system is shown in
Figure 2.
5.4 Strip-Chart Recorder.
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6. Reagents
6.1 Sodium sulfite - 0.1 M, ACS reagent grade (12.6 g/L).
6.2 Nitric acid - concentrated.
6.3 Nitrate-Wash Solution (5000 mg NOg/L) - Prepare a nitrate-wash
solution by transferring approximately 8.2 gm of potassium nitrate
into a 1-litre volumetric flask and diluting to volume with reagent
water.
6.4 Carbon dioxide - gas, 99.9% purity.
6.5 Oxygen - 99.9% purity.
6.6 Nitrogen - prepurified.
6.7 70% Acetic acid in water - Dilute 7 volumes of acetic acid with 3
volumes of water.
6.8 Trichlorophenol solution, stock (1 yL = 10 yg Cl") - Prepare a
stock solution by weighing accurately 1.856 gm of trichlorophenol
into a 100-mL volumetric flask. Dilute to volume with methanol.
6.9 Trichlorophenol solution, calibration (1 yL = 500 ng Cl") -
Dilute 5 ml of the trichlorophenol stock solution to 100 ml with
methanol.
6.10 Trichlorophenol standard, instrument-calibration - First, nitrate
wash a single column packed with 40 mg of activated carbon as
instructed for sample analysis, and then inject the column with
10 yL of the calibration solution.
6.11 Trichlorophenol standard, adsorption-efficiency (100 yg C1"/L) -
Prepare a adsorption-efficiency standard by injecting 10 yL of
stock solution into 1 liter of reagent water.
6.12 Reagent water - Reagent water is defined as a water in which an
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interferent is not observed at the method detection limit of each
parameter of interest.
6.13 Blank standard - The reagent water used to prepare the calibration
standard should be used as the blank standard.
7. Calibration
7.1 Check the adsorption efficiency of each newly-prepared batch of
carbon by analyzing 100 ml of the adsorption-efficiency standard,
in duplicate, along with duplicates of the blank standard. The net
recovery should be within 5% of the standard value.
7.2 Nitrate-wash blanks (Method Blanks) - Establish the repeatability
of the method background each day by first analyzing several
nitrate-wash blanks. Monitor this background by spacing nitrate-
wash blanks between each group of eight pyrolysis determinations.
7.2.1 The nitrate-wash blank values are obtained on single columns
packed with 40 mg of activated carbon. Wash with the
nitrate solution as instructed for sample analysis, and then
pyrolyze the carbon.
7.3 Pyrolyze duplicate instrument-calibration standards and the blank
standard each day before beginning sample analysis. The net
response to the calibration-standard should be within 3% of the
calibration-standard value. Repeat analysis of the
instrument-calibration standard after each group of eight pyrolysis
determinations, and before resuming sample analysis after cleaning
or reconditioning the titration cell or pyrolysis system.
8. Sample Preparation
8.1 Special care should be taken in the handling of the sample to
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minimize the loss of volatile organohalides. The adsorption
procedure should be performed simultaneously on duplicates.
8.2 Reduce residual chlorine by the addition of sulfite (1 ml of 0.1 M
per liter of sample). Addition of sulfite should be done at the
time of sampling if the analysis is meant to determine the TOX
concentration at the time of sampling. It should be recognized
that TOX may increase on storage of the sample. Samples should be
stored at 4°C without headspace.
8.3 Adjust pH of the sample to approximately 2 with concentrated HNOg
just prior to adding the sample to the reservoir.
9. Adsorption Procedure
9.1 Connect two columns in series, each containing 40 mg of
100/200-mesh activated carbon.
9.2 Fill the sample reservoir, and pass a metered amount of sample
through the activated-carbon columns at a rate of approximately
3 mL/min. NOTE: 100 ml of sample is the preferred volume for
concentrations of TOX between 5 and 500 ug/L; .50 ml for 501 to 1000
yg/L, and 25 ml for 1001 to 2000 ug/L.
9.3 Wash the columns-in-series with 2 mL of the 5000-mg/L nitrate
solution at a rate of approximately 2 mL/min to displace inorganic
chloride ions.
10. Pyrolysis Procedure
10.1 The contents of each column is pyrolyzed separately. After rinsing
with the nitrate solution, the columns should be protected from the
atmosphere and other sources of contamination until ready for
further analysis.
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10.2 Pyrolysis of the sample is accomplished in two stages. The
volatile components are pyrolyzed in a COp-rich atmosphere at a
low temperature to assure the conversion of brominated
trihalomethanes to a titratable species. The less volatile
components are then pyrolyzed at a high temperature in an CL-rich
atmosphere.
NOTE: The quartz sampling boat should have been previously muffled
at 800 C for at least 2 to 4 minutes as in a previous analysis,
and should be cleaned of any residue by vacuuming.
10.3 Transfer the contents of each column to the quartz boat for
individual analysis.
10.4 If the Dohrmann MC-1 is used for pyrolysis, manual instructions are
followed for gas flow regulation. If the MCT-20 is used, the
information on the diagram in Figure 3 is used for gas flow
regulation.
10.5 Position the sample for 2 minutes in the 200°C zone of the
pyrolysis tube. For the MCTS-20, the boat is positioned just
outside the furnace entrance.
10.6 After 2 minutes, advance the boat into the 800°C zone (center) of
the pyrolysis furnace. This second and final stage of pyrolysis
may require from 6 to 10 minutes to complete.
11. Detection
The effluent gases are directly analyzed in the microcoulometric-titra-
tion cell. Carefully follow manual instructions for optimizing cell
performance.
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12. Breakthrough
Because the background bias can be of such an unpredictable nature, it
can be especially difficult to recognize the extent of breakthrough of
organohalides from one column to another. All second-column
measurements for a properly operating system should not exceed
10-percent of the two-column total measurement. If the 10-percent
figure is exceeded, one of three events can have happened. Either the
first column was overloaded and a legitimate measure of breakthrough was
obtained - in which case taking a smaller sample may be necessary; or
channeling or some other failure occurred - in which case the sample may
need to be rerun; or a high, random, bias occurred and the result should
be rejected and the sample rerun. Because knowing which event has
occurred may not be possible, a sample analysis should be repeated often
enough to gain confidence in results. As a general rule, any analyses
that is rejected should be repeated whenever sample is available. In
the event that the second-column measurement is equal to or less than
the nitrate-wash blank value, the second-column value should be
disregarded.
13. Quality Control
13.1 Before performing any analyses, the analyst must demonstrate the
ability to generate acceptable accuracy and precision with this
procedure by the analysis of appropriate quality-control check
samples.
13.2 The laboratory must develop and maintain a statement of method
accuracy for their laboratory. The laboratory should update the
accuracy statement regularly as new recovery measurements are made.
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13.3 It is recommended that the laboratory adopt additional
quality-assurance practices for use with this method. The specific
practices that would be most productive will depend upon the needs
of the laboratory and the nature of the samples. Field duplicates
may be analyzed to monitor the precision of the sampling
technique. Whenever possible, the laboratory should perform
analysis of standard reference materials and participate in
relevant performance-evaluation studies.
14. Calculations
OX as Cl~ is calculated using the following formula:
(cr c3) + (c2 - c3 ) u ug/L Total Organ1c Ha-|ide
where:
C, = ug Cl~ on the first column in series
C~ - ug Cl" on the second column in series
Co = predetermined, daily, average, method-blank value
(nitrate-wash blank for a 40-mg carbon column)
V = the sample volume in L
15. Accuracy and Precision
These procedures have been applied to a large number of drinking-water
samples. The results of these analysis are summarized in Tables I and
II.
16. Reference
Dressman, R., Najar, G., Redzikowski, R., paper presented at the
Proceedings of the American Water Works Association Water Quality
Technology Conference, Philadelphia, Dec. 1979.
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TABLE I
PRECISION AND ACCURACY DATA FOR MODEL COMPOUNDS
Model Dose Dose Average Standard
Compound ug/L as yg/L Cl % Recovery Deviation
CHC13 98 88 89 14
CHBrCl2 160 106 98 9
CHBr2C1 155 79 86 11
CHBr3 160 67 111 8
Pentachlorophenol 120 80 93 9
TABLE II
PRECISION DATA ON TAP WATER ANALYSIS
Avg. halide Standard
Sample ug Cl/L Deviation
A 71 4.3
B 94 7.0
C 191 6.1
No. Of
Replicates
10
11
13
11
7
No. of
Replicates
8
6
4
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I\l2
SAMPLE
RESERVOIR
(1 of 4)
NITRATE WASH
RESERVOIR
GAG COLUMN 1
GAC COLUMN 2
Figure 1. Adsorption Schematic
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SPARGING
DEVICE
TITRATION
pel I
PYROLYSIS
FURNACE
BOAT
INLET
MICROCOULOMETER
WITH INTEGRATOR
STRIP CHART
RECORDER
ADSORPTION
MODULE
Figure 2. CAOX Analysis System Schematic
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B
PYROLYSIS FURNACE
SINGLE BOAT OUTLET
CONNECT TO
BOAT-INLET
PORTS A
II 00
i |l| I"' *V^^y^~|
4- II 1
543 21
IIOiVENT CAPPEDI
f «
1
1
H
.sx r n
N.Al .
' * * i \ <
i ' «
Vr\ LI
0 c— ' | CO. 50 ml/min O, 100 ml/min
| CARRIER OUT REACTANT OUT
! o o
I
I
I
L_Un
I ^
i
r
COi 100 ml/min
AUXILIARY
OUT
1
1
Figure 3. Rear view plumbing schematic for MCTS-20 system.
Valve A is set for first-stage combustion. O2 venting
(push/pull valve out). Port B enters inner combustion
tube; Port C enters outer combustion tube.
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