Method
1650
Adsorbable Organic Hal ides
by Adsorption and Couiometric Titration
Revision C
August 1997
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Acknowledgments
This method was prepared under the direction of William A. Telliard
of the Engineering and Analysis Division within EPA's Office of Water.
This document was prepared under EPA Contract No. 68-C3-0337 by
DynCorp, Inc. with assistance from its subcontractor Interface, Inc.
Disclaimer
This method has been reviewed by the Engineering and Analysis Division, U.S. Environmental
Protection Agency, and approved for publication. Mention of trade names or commercial products
does not constitute endorsement or recommendation for use.
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Method 1650
Adsorbable Organic Hal ides
by Adsorption and Couiometric Titration
1.0 Scope and Application
1.1 This method is for determination of adsorbable organic halides (AOX) associated with the
Clean Water Act, the Resource Conservation and Recovery Act; the Comprehensive
Environmental Response, Compensation, and Liability Act; and other organic halides
amenable to combustion and couiometric titration. The method is designed to meet the
survey and monitoring requirements of the Environmental Protection Agency (EPA).
1.2 The method is applicable to the determination of AOX in water and wastewater. This
method is a combination of several existing methods for organic halide measurements
(References 1 through 7).
1.3 The method can be used to measure organically-bound halides (chlorine, bromine, iodine)
present in dissolved or suspended form. Results are reported as organic chloride (CI").
The detection limit of the method is usually dependent on interferences rather than
instrumental limitations. A method detection limit (MDL; Reference 8) of 6.6 (Jg/L, and a
minimum level (ML; Section 18) of 20 (Jg/L, can be achieved with no interferences
present.
1.4 This method is for use by or under the supervision of analysts experienced in the use of a
combustion/micro-coulometer. Each laboratory that uses this method must demonstrate
the ability to generate acceptable results using the procedures described in Section 9.2.
1.5 Any modification of the method beyond those expressly permitted (Section 9.1.2) is subject
to application and approval of an alternate test procedure under 40 CFR 136.4 and 136.5.
2.0 Summary of Method
2.1 Sample preservation: Residual chlorine that may be present is removed by the addition of
sodium thiosulfate. Samples are adjusted to a pH < 2 and maintained at 0 to 4°C until
analysis.
2.2 Sample analysis: Organic halide in water is determined by adsorption onto granular
activated carbon (GAC), washing the adsorbed sample and GAC to remove inorganic
halide, combustion of the sample and GAC to form the hydrogen halide, and titration of
the hydrogen halide with a micro-coulometer, as shown in Figure 1.
2.3 Micro-coulometer.
2.3.1 This detector operates by maintaining a constant silver-ion concentration in a
titration cell. An electric potential is applied to a solid silver electrode to
produce silver ions in the cell. As hydrogen halide produced from the
combustion of organic halide enters the cell, it is partitioned into an acetic acid
electrolyte where it precipitates as silver halide. The current produced is
integrated over the combustion period. The electric charge is proportional to the
number of moles of halogen captured in the cell (Reference 6).
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Method 1650
2.3.2 The mass concentration of organic halides is reported as an equivalent
concentration of organically bound chloride (CI").
3.0 Definitions
3.1 Adsorbable organic halides is defined as the analyte measured by this method. The nature
of the organo-halides and the presence of semi-extractable material will influence the
amount measured and interpretation of results.
3.2 Definitions for terms used in this method are given in the glossary at the end of the method
(Section 18).
4.0 Interferences
4.1 Solvents, reagents, glassware, and other sample processing hardware may yield elevated
readings from the micro-coulometer. All materials used in the analysis shall be
demonstrated to be free from interferences under the conditions of analysis by running
method blanks initially and with each sample batch (samples started through the
adsorption process in a given eight-hour shift, to a maximum of 20 samples). Specific
selection of reagents and purification of solvents may be required.
4.2 Glassware is cleaned by detergent washing in hot water, rinsing with tap water and
distilled water, capping with aluminum foil, and baking at 450°C for at least one hour.
For some glassware, immersion in a chromate cleaning solution prior to detergent washing
may be required. If blanks from glassware without cleaning or with fewer cleaning steps
show no detectable organic halide, the cleaning steps that do not eliminate organic halide
may be omitted.
4.3 Most often, contamination results from methylene chloride vapors in laboratories that
perform organic extractions. Heating, ventilating, and air conditioning systems that are
shared between the extraction laboratory and the laboratory in which organic halide
measurements are performed transfer the methylene chloride vapors to the air in the
organic halide laboratory. Exposure of the activated carbon used in the analysis results in
contamination. Separate air handling systems, charcoal filters, and glove boxes can be
used to minimize this exposure.
4.4 Activated carbon.
4.4.1 The purity of each lot of activated carbon must be verified before each use by
measuring the adsorption capacity and the background level of halogen (Section
9.5). The stock of activated carbon should be stored in its granular form in a
glass container that is capped tightly. Protect carbon at all times from sources
of halogen vapors.
4.4.2 Inorganic substances such as chloride, chlorite, bromide, and iodide will adsorb
on activated carbon to an extent dependent on their original concentration in the
aqueous solution and the volume of sample adsorbed. Treating the activated
carbon with a solution of nitrate causes competitive desorption of inorganic
halide species. However, if the inorganic halide concentration is greater than
2,000 times the organic halide concentration, artificially high results may be
obtained.
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Method 1650
4.4.3 Halogenated organic compounds that are weakly adsorbed on activated carbon
are only partially recovered from the sample. These include certain alcohols and
acids such as chloroethanol and chloroacetic acid that can be removed from
activated carbon by the nitrate wash.
4.5 Polyethylene gloves should be worn when handling equipment surfaces in contact with the
sample to prevent transfer of contaminants that may be present on the hands.
5.0 Safety
5.1 The toxicity or carcinogenicity of each reagent used in this method has not been precisely
determined; however, each chemical substance should be treated as a potential health
hazard. Exposure to these substances should be reduced to the lowest possible level. 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 safety data sheets (MSDSs) should be made available to all personnel involved in
the chemical analysis. Additional information on laboratory safety can be found in
References 9 through 11.
5.2 This method employs strong acids. Appropriate clothing, gloves, and eye protection
should be worn when handling these substances.
5.3 Field samples may contain high concentrations of toxic volatile compounds. Sample
containers should be opened in a hood and handled with gloves that will prevent exposure.
6.0 Equipment and Supplies
NOTE: Brand names, suppliers, and part numbers are for illustrative
purposes only. No endorsement is implied. Equivalent performance may be
achieved using apparatus and materials other than those specified here, but
demonstration of equivalent performance that meets the requirements of this
method is the responsibility of the laboratory.
6.1 Sampling equipment.
6.1.1 Bottles: 100- to 4000-mL, amber glass, sufficient for all testing (Section 8.2).
Detergent water wash, chromic acid rinse, rinse with tap and distilled water,
cover with aluminum foil, and heat to 450°C for at least one hour before use.
6.1.2 PTFE liner: Cleaned as above and baked at 100 to 200°C for at least one hour.
6.1.3 Bottles and liners must be lot certified to be free of organic halide by running
blanks according to this method.
6.2 Scoop for granular activated carbon (GAC): Capable of precisely measuring 40 mg (±5
mg) GAC (Dohrmann Measuring Cup 521-021, or equivalent).
6.3 Batch adsorption and filtration system.
6.3.1 Adsorption system: Rotary shaker, wrist action shaker, ultrasonic system, or
other system for assuring thorough contact of sample with activated carbon.
Systems different from the one described below must be demonstrated to meet
the performance requirements in Section 9 of this method.
6.3.1.1 Erlenmeyer flasks: 250- to 1500-mL with ground-glass stopper, for
use with rotary shaker.
6.3.1.2 Shake table: Sybron Thermolyne Model LE "Big Bill" rotator/shaker,
or equivalent.
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Method 1650
6.3.1.3 Rack attached to shake table to permit agitation of 16 to 25 samples
simultaneously.
6.3.2 Filtration system (Figure 2).
6.3.2.1 Vacuum filter holder: Glass, with fritted-glass support (Fisher Model
09-753E, or equivalent).
6.3.2.2 Polycarbonate filter: 0.40 to 0.45 micron, 25-mm diameter (Micro
Separations Inc, Model K04CP02500, or equivalent).
6.3.2.3 Filter forceps: Fisher Model 09-753-50, or equivalent, for handling
filters. Two forceps may better aid in handling filters. Clean by
washing with detergent and water, rinsing with tap and deionized
water, and air drying on aluminum foil.
6.3.2.4 Vacuum flask: 500- to 1500-mL (Fisher 10-1800, or equivalent).
6.3.2.5 Vacuum Source: A pressure/vacuum pump, rotary vacuum pump, or
other vacuum source capable of providing at least 610 mm (24 in.)
Hg vacuum at 30 L/min free air displacement.
6.3.2.6 Stopper and tubing to mate the filter holder to the flask and the flask
to the pump.
6.3.2.7 Polyethylene gloves: (Fisher 11-394-110-B, or equivalent).
6.4 Column adsorption system.
6.4.1 Adsorption module: Dohrmann AD-2, Mitsubishi TXA-2, or equivalent with
pressurized sample and nitrate-wash reservoirs, adsorption columns, column
housings, gas and gas pressure regulators, and receiving vessels. For each
sample reservoir, there are two adsorption columns connected in series. A small
steel funnel for filling the columns and a rod for pushing out the carbon are also
required. A schematic of the column adsorption system is shown in Figure 3.
6.4.2 Adsorption columns: Pyrex, 5 ± 0.2 cm long x 2 mm ID, to hold 40 mg of
granular activated carbon (GAC).
6.4.3 Cerafelt: Johns-Manville, or equivalent, formed into plugs using stainless steel
borer (2 mm ID) with ejection rod (available from Dohrmann or Mitsubishi) to
hold 40 mg of granular activated carbon (GAC). Caution: Handle Cerafelt with
gloves.
6.4.4 Column holders: To support adsorption columns.
6.5 Combustion/micro-coulometer system: Commercially available as a single unit or
assembled from parts. At the time of the writing of this method, organic halide units were
commercially available from the Dohrmann Division of Rosemount Analytical, Santa
Clara, California; Euroglas BV, Delft, the Netherlands; and Mitsubishi Chemical
Industries, Ltd., Tokyo, Japan.
6.5.1 Combustion system: Older systems may not have all of the features shown in
Figure 4. These older systems may be used provided the performance
requirements (Section 9) of this method are met.
6.5.1.1 Combustion tube: Quartz, capable of being heated to 800 to 1000°C
and accommodating a boat sampler. The tube must contain an air
lock for introduction of a combustion boat, connections for purge and
combustion gas, and connection to the micro-coulometer cell.
6.5.1.2 Tube furnace capable of controlling combustion tube in the range of
800 to 1000°C.
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Method 1650
Boat sampler: Capable of holding 35 to 45 mg of activated carbon
and a polycarbonate filter, and fitting into the combustion tube
(Section 6.5.1.1). Some manufacturers offer an enlarged boat and
combustion tube for this purpose. Under a time-controlled sequence,
the boat is first moved into an evaporation zone where water and other
volatiles are evaporated, and then into the combustion zone where the
carbon and all other organic material in the boat are burned in a
flowing oxygen stream. The evolved gases are transported by a non-
reactive carrier gas to the micro-coulometer cell.
Motor driven boat sampler: Capable of advancing the combustion
boat into the furnace in a reproducible time sequence. A suggested
time sequence is as follows:
A. Establish initial gas flow rates: 160 mL/min C02; 40 mL/min
02.
B. Sequence start.
C. Hold boat in hatch for five seconds to allow integration for
baseline subtraction.
D. Advance boat into vaporization zone.
E. Hold boat in vaporization zone for 110 seconds.
F. Establish gas flow rates for combustion: 200 mL/min 02; 0
mL/min C02; advance boat into pyrolysis zone (800°C).
G. Hold boat in pyrolysis zone for six minutes.
H. Return gas flow rates to initial values; retract boat into hatch
to cool and to allow remaining HX to be swept into detector
(approximately two minutes).
I. Stop integration at 10 minutes after sequence start.
NOTE: If the signal from the detector does not return to baseline, it
may be necessary to extend the pyrolysis time.
The sequence above may need to be optimized for each instrument.
6.5.1.5 Absorber: Containing sulfuric acid to dry the gas stream after
combustion to prevent backflush of electrolyte is highly
recommended.
6.5.2 Micro-coulometer system: Capable of detecting the equivalent of 0.2 jjg of CI
at a signal-to-noise ratio of 2; capable of detecting the equivalent of 1 (jg of CI
with a relative standard deviation less than 10%, and capable of accumulating a
minimum of the equivalent of 500 pg of CI before a change of electrolyte is
required.
6.5.2.1 Micro-coulometer cell: The three cell designs presently in use are
shown in Figure 1. Cell operation is described in Section 2.
6.5.2.2 Cell controller: Electronics capable of measuring the small currents
generated in the cell and accumulating and displaying the charge
produced by hydrogen halides entering the cell. A strip-chart recorder
is desirable for display of accumulated charge.
6.5.1.3
6.5.1.4
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Method 1650
6.6 Miscellaneous glassware—nominal sizes are specified below; other sizes may be used, as
necessary.
6.6.1 Volumetric flasks: 5-, 10-, 25-, 50-, 100-, and 1000-mL.
6.6.2 Beakers: 100-, 500-, and 1000-mL.
6.6.3 Volumetric pipets: 1- and 10-mL with pipet bulbs.
6.6.4 Volumetric micro-pipets: 10-, 20-, 50-, 100-, 200-, and 500-(iL with pipet
control (Hamilton 0010, or equivalent).
6.6.5 Graduated cylinders: 10-, 100-, and 1000-mL.
6.7 Micro-syringes: 10-, 50-, and 100-fjL.
6.8 Balances.
6.8.1 Top-loading, capable of weighing 0.1 g.
6.8.2 Analytical, capable of weighing 0.1 mg.
6.9 pH meter.
6.10 Wash bottles: 500- to 1000-mL, PTFE or polyethylene.
6.11 Strip-chart recorder: suggested but not required—useful for determining end of integration
(Section 11.4.2).
7.0 Reagents and Standards
7.1 Granular activated carbon (GAC): 75 to 150 (jm (100 to 200 mesh); (Dohrmann,
Mitsubishi, Carbon Plus, or equivalent), with chlorine content less than 1 jjg CI per scoop
(< 25 jjg CI per gram), adsorption capacity greater than 1000 jjg CI (as 2,4,6-
trichlorophenol) per scoop (>25,000 pg/g). inorganic halide retention of less than 1 jjg CI
per scoop in the presence of 10 mg of inorganic halide (< 20 jjg CI per gram in the
presence of 2500 mg of inorganic halide), and that meets the other test criteria in this
method.
7.2 Reagent water: Water in which organic halide is not detected by this method.
7.2.1 Preparation: Reagent water may be generated by:
7.2.1.1 Activated carbon: Pass tap water through a carbon bed (Calgon
Filtrasorb-300, or equivalent).
7.2.1.2 Water purifier: Pass tap water through a purifier (Millipore Super Q,
or equivalent).
7.2.2 pH adjustment: Adjust the pH of the reagent water to < 2 with nitric acid for all
reagent water used in this method, except for the acetic acid solution (Section
7.13).
7.3 Nitric acid (HN03): Concentrated, analytical grade.
7.4 Sodium chloride (NaCl) solution (100 (jg/mL of CI"): Dissolve 0.165 g NaCl in 1000 mL
reagent water. This solution is used for cell testing and for the inorganic halide rejection
test.
7.5 Ammonium chloride (NH4C1) solution (100 (jg/mL of CI"): Dissolve 0.1509 g NH4C1 in
1000 mL reagent water.
7.6 Sulfuric acid: Reagent grade (specific gravity 1.84).
7.7 Oxygen: 99.9% purity.
7.8 Carbon Dioxide: 99.9% purity.
7.9 Nitrate stock solution: In a 1000-mL volumetric flask, dissolve 17 g of NaN03 in
approximately 100 mL of reagent water, add 1.4 mL nitric acid (Section 7.3) and dilute to
the mark with reagent water.
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Method 1650
7.10 Nitrate wash solution: Dilute 50 mL of nitrate stock solution (Section 7.9) to 1000 mL
with reagent water.
7.11 Sodium thiosulfate (Na2S203) solution (1 N): Weigh 79 grams of Na2S203 in a 1-L
volumetric flask and dilute to the mark with reagent water.
7.12 Trichlorophenol solutions.
NOTE: The calibration solutions in this section employ 100-mL volumes. For
determinations requiring a larger or smaller volume, increase or decrease the
size of the volumetric flasks commensurately. For example, if a 1-L sample is to
be analyzed, use 1000-mL flasks (Sections 7.12.3.1 and 7.12.4) and 10 times the
volume of reagent water (Sections 7.12.3.1 and 7.12.4). The volume of stock
solution added to the calibration solutions and precision and recovery (PAR)
test solution remain as specified (Sections 7.12.3.2 and 7.12.4) so that the same
amount of chloride is delivered to the coulometric cell regardless of the volume
of the calibration and PAR solutions.
7.12.1 Methanol: HPLC grade.
7.12.2 Trichlorophenol stock solution (1.0 mg/mL of CI"): Dissolve 0.186 g of 2,4,6-
trichlorophenol in 100 mL of halide-free methanol.
7.12.3 Trichlorophenol calibration solutions.
7.12.3.1 Place approximately 90 mL of reagent water in each of five 100-mL
volumetric flasks.
7.12.3.2 Using a calibrated micro-syringe or micro-pipets, add 2, 5, 10, 30,
and 80 |_iL of the trichlorophenol stock solution (Section 7.12.2) to the
volumetric flasks and dilute each to the mark with reagent water to
produce calibration solutions of 2, 5, 10, 30, and 80 jjg CI per 100
mL of solution (20, 50, 100, 300, and 800 (Jg/L).
7.12.3.3 Some instruments may have a calibration range that does not extend
to 800 (jg/L (80 jjg of CI ). For those instruments, a narrower
dynamic range may be used. However, if the concentration of halide
in a sample exceeds that range, the sample must be diluted to bring
the concentration within the range calibrated.
7.12.4 Trichlorophenol precision and recovery (PAR) test solution (10 (jg/L of CI"):
Partially fill a 100-mL volumetric flask, add 10 (iL of the stock solution
(Section 7.12.2), and dilute to the mark with reagent water.
7.13 Acetic acid solution: Containing 30 to 70% acetic acid in deionized water, per the
instrument manufacturer's instructions.
8.0 Sample Collection, Preservation, and Storage
8.1 Sample preservation.
8.1.1 Residual chlorine: If the sample is known or suspected to contain free chlorine,
the chlorine must be reduced to eliminate positive interference that may result
from continued chlorination reactions. A knowledge of the process from which
the sample is collected may be of value in determining whether dechlorination is
necessary. Immediately after sampling, test for residual chlorine using the
following method or an alternative EPA method (Reference 12):
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Method 1650
8.1.1.1 Dissolve a few crystals of potassium iodide in the sample and add
three to five drops of a 1% starch solution. A blue color indicates the
presence of residual chlorine.
8.1.1.2 If residual chlorine is found, add 1 mL of sodium thiosulfate solution
(Section 7.11) for each 2.5 ppm of free chlorine or until the blue color
disappears. Do not add an excess of sodium thiosulfate. Excess
sodium thiosulfate may cause decomposition of a small fraction of the
OX.
8.1.2 Acidification: Adjust the pH of aqueous samples to < 2 with nitric acid.
Acidification inhibits biological activity and stabilizes chemical degradation,
including possible dehalogenation reactions that may occur at high pH.
Acidification is necessary to facilitate thorough adsorption.
8.1.3 Refrigeration: Maintain samples at a temperature of 0 to 4°C from time of
collection until analysis.
8.2 Collect the amount of sample necessary for analysis (Section 11) and all QC tests (Section
9) in an amber glass bottle of the appropriate size (Section 6.1.1).
8.3 Analyze samples no less than three days nor more than six months after collection.
9.0 Quality Control
9.1 Each laboratory that uses this method is required to operate a formal quality assurance
program. The minimum requirements of this program consist of an initial demonstration
of laboratory capability, an ongoing analysis of standards and blanks as tests of continued
performance, and analysis of matrix spike and matrix spike duplicate (MS/MSD) samples
to assess accuracy and precision. Laboratory performance is compared to established
performance criteria to determine if the results of analyses meet the performance
characteristics of the method.
9.1.1 The laboratory shall make an initial demonstration of the ability to produce
acceptable results with this method. This ability is demonstrated as described in
Section 9.2.
9.1.2 The laboratory is permitted to modify this method to improve separations or
lower the costs of measurements, provided that all performance specifications
are met. Each time a modification is made to the method, the laboratory is
required to repeat the procedures in Sections 9.2.2 and 10 to demonstrate
continued method performance. If the detection limit of the method will be
affected by the modification, the laboratory should demonstrate that the MDL
(40 CFR 136, Appendix B) is less than or equal to the MDL in this method or
one-third the regulatory compliance level, whichever is higher.
9.1.3 The laboratory shall spike 10% of the samples with known concentrations of
2,4,6-trichlorophenol to monitor method performance and matrix interferences
(interferences caused by the sample matrix). This test is described in Section
9.3. When results of these spikes indicate atypical method performance for
samples, the samples are diluted to bring method performance within acceptable
limits.
9.1.4 Analyses of blanks are required to demonstrate freedom from contamination.
The procedures and criteria for analysis of blanks are described in Section 9.4.
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Method 1650
9.1.5 The laboratory shall, on an ongoing basis, demonstrate through the analysis of
the precision and recovery (PAR) standard that the analysis system is in control.
These procedures are described in Section 9.10.
9.1.6 The laboratory shall perform quality control tests on the granular activated
carbon. These procedures are described in Section 9.5.
9.1.7 Samples are analyzed in duplicate to demonstrate precision. These procedures
are described in Section 9.6.
9.2 Initial demonstration of laboratory capability
9.2.1 Method Detection Limit (MDL)—To estalish the ability to detect AOX, the
laboratory should determine the MDL per the procedure in 40 CFR 136,
Appendix B using the apparatus, reagents, and standards that will be used in the
practice of this method. An MDL less than or equal to the MDL in Section 1.3
should be achieved prior to the practice of this method.
9.2.2 Initial precision and recovery (IPR): To establish the ability to generate
acceptable precision and recovery, the laboratory shall perform the following
operations:
9.2.2.1 Analyze four aliquots of the PAR standard (Section 7.12.4) and a
method blank according to the procedures in Sections 9.4 and 11.
9.2.2.2 Using the blank-subtracted results of the set of four analyses, compute
the average percent recovery (X) and the standard deviation of the
percent recovery (s) for the results.
9.2.2.3 The average percent recovery shall be in the range of 81 to 114 (jg/L
and the standard deviation shall be less than 8 pg/L. If X and s meet
these acceptance criteria, system performance is acceptable and
analysis of blanks and samples may begin. If, however, s exceeds the
precision limit or X falls outside the range for recovery, system
performance is unacceptable. In this case, correct the problem and
repeat the test.
9.3 Matrix spikes: The laboratory shall spike a minimum of 10% of samples from a given
matrix type (e.g., C-stage filtrate, produced water, treated effluent) in duplicate
(MS/MSD). If only one sample from a given matrix type is analyzed, an additional two
aliquots of that sample shall be spiked.
9.3.1 The concentration of the analytes spiked into the MS/MSD shall be determined
as follows:
9.3.1.1 If, as in compliance monitoring, the concentration of OX is being
checked against a regulatory concentration limit, the spiking level
shall be at that limit or at one to five times higher than the background
concentration determined in Section 9.3.2, whichever concentration is
higher.
9.3.1.2 If the concentration of OX is not being checked against a regulatory
limit, the spike shall be at the concentration of the precision and
recovery standard (PAR; Section 7.12.4) or at one to five times higher
than the background concentration determined in Section 9.3.2,
whichever concentration is higher.
9.3.2 Analyze one sample out of each batch of 10 samples from each site to determine
the background concentration of AOX. If necessary, prepare a solution of
2,4,6-trichlorophenol appropriate to produce a level in the sample one to five
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Method 1650
times the background concentration. Spike two additional sample aliquots with
spiking solution and analyze them to determine the concentration after spiking.
9.3.2.1 Compute the percent recovery of each analyte in each aliquot:
°/ Recovery - (Found - Background)
where:
T is the true value of the spike
9.3.2.2 Compute the relative percent difference (RPD) between the two
results (not between the two recoveries) as described in Section 12.4.
9.3.2.3 If the RPD is less than 20%, and the recoveries for the MS and MSD
are within the range of 78 to 116%, the results are acceptable.
9.3.2.4 If the RPD is greater than 20%, analyze two aliquots of the precision
and recovery standard (PAR).
9.3.2.4.1 If the RPD for the two aliquots of the PAR is
greater than 20%, the analytical system is out of
control. In this case, repair the problem and
repeat the analysis of the sample batch, including
the MS/MSD.
9.3.2.4.2 If, however, the RPD for the two aliquots of the
PAR is less than 20%, dilute the sample chosen
for the MS/MSD by a factor of 2 - 10 (to remain
within the working range of the analytical
system) and repeat the MS/MSD test. If the
RPD is still greater than 20%, the result may not
be reported for regulatory compliance purposes.
In this case, choose another sample for the
MS/MSD and repeat analysis of the sample
batch.
9.3.2.5 If the percent recovery for both the MS and MSD are less than 78%
or greater than 116%, analyze the precision and recovery (PAR)
standard.
9.3.2.5.1 If the recovery of the PAR is outside the 78 to
116% range, the analytical system is out of
control. In this case, repair the problem and
repeat the analysis of the sample batch, including
the MS/MSD.
9.3.2.5.2 If the recovery of the PAR is within the range of
78 to 116%, dilute the sample, MS, and MSD by
a factor of 2 - 10 (to remain within the working
range of the analytical system) and re-analyze. If
the results of the dilute analyses remain outside
of the acceptable range, these results may not be
reported for regulatory compliance purposes. In
this case, choose another sample for the
MS/MSD and repeat the analysis of the sample
batch.
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Method 1650
9.4 Blanks.
9.4.1 Reagent water blanks: Analyzed to demonstrate freedom from contamination.
9.4.1.1 Analyze a reagent water blank with each batch of samples. The blank
must be analyzed immediately preceding calibration verification to
allow for blank subtraction and to demonstrate freedom from
contamination and memory effects, and must include all details of the
procedure to be followed when analyzing samples.
9.4.1.2 Prepare the reagent water blank using a volume of reagent water
equivalent to the volume used for sample preparation (Section 11.1).
If using the micro-column procedure, adsorb the method blank using
two columns, as described in Section 11. Combust the GAC from
each column separately, as described in Section 11.
9.4.1.3 If the result from the blank from the batch method or the sum of the
results from two columns is more than 20 pg/L. analysis of samples is
halted until the source of contamination is eliminated and a blank
shows no evidence of contamination at this level.
9.4.2 Nitrate-washed GAC blanks: Analyzed daily to demonstrate that the GAC is
free from contamination.
9.4.2.1 Nitrate-washed GAC blank for the batch procedure: Analyze a batch
nitrate-washed GAC blank by adding a scoop of dry GAC to the
assembled filter apparatus containing the polycarbonate membrane
and washing the GAC with the nitrate wash solution (Section 7.10)
using the procedure in Section 11.2.6.
9.4.2.2 Nitrate-washed GAC blank for the column procedure: Analyze a
column nitrate-washed GAC blank by assembling two carbon
columns in series and washing the columns with the nitrate wash
solution (Section 7.10) using the procedure in Section 11.3.4.2.
Analyze the GAC in each column separately. The results of the
second analysis must be within ±0.2 jjg CI" of the first. A difference
greater than 0.2 (jg CI" indicates a lack of homogeneity in the GAC
that could introduce unacceptable variability. If the difference
exceeds this amount, the GAC should be replaced.
9.4.3 The result for the reagent water blank (Section 9.4.1) shall not exceed the result
for the nitrate wash blank (Section 9.4.2.1 or 9.4.2.2) by more than 0.5 jjg CI".
9.5 Granular activated carbon (GAC) batch testing: Each lot number or batch of activated
carbon received from a supplier is tested once before use to ensure adequate quality. Use
only GAC that meets the test criteria below.
9.5.1 Contamination test: Analyze a scoop of GAC. Reject carbon if the amount of
OX exceeds 1 jjg (25 jjg Cl /g).
9.5.2 Inorganic chloride adsorption test: Attempt to adsorb NaCl from 100 mL of a
solution containing 100 mg/L in reagent water. Wash with nitrate solution and
analyze. The amount of halide should be less than 1 jjg CI larger than the
blank. A larger amount indicates significant uptake of inorganic chloride by the
carbon. Reject carbon if the 1 jjg level is exceeded.
9.6 Samples that are being used for regulatory compliance purposes shall be analyzed in
duplicate.
-------
Method 1650
9.6.1 The procedure for preparing duplicate sample aliquots is described in Section
11.5.
9.6.2 Calculate the RPD by following the same procedure described in Section 12.4.
9.6.3 If the RPD is greater than 20%, the analyses must be repeated.
9.6.4 If the RPD remains greater than 20%, the result may not be reported for
regulatory compliance purposes.
9.7 The specifications in this method can be met if the apparatus used is calibrated properly
and maintained in a calibrated state. The standards used for calibration (Section 10),
calibration verification (Section 9.9), and for initial (Section 9.2.2) and ongoing (Section
9.10) precision and recovery should be identical, so that the most precise results will be
obtained.
9.8 Depending on specific program requirements, field duplicates may be collected to
determine the precision of the sampling technique.
9.9 At the beginning and end of each eight-hour shift during which analyses are performed,
system performance and calibration are verified. Verification of system performance and
calibration may be performed more frequently, if desired.
9.9.1 If performance and calibration are verified at the beginning and end of each shift
(or more frequently), samples analyzed during that period are considered valid.
9.9.2 If performance and calibration are not verified at both the beginning and end of
a shift (or more frequently), samples analyzed during that period must be
reanalyzed.
9.9.3 If calibration is verified at the beginning of a shift, recalibration using the five
standards described in Section 10.6 is not necessary; otherwise, the instrument
must be recalibrated prior to analyzing samples (Section 10).
9.9.4 Cell maintenance and other changes to the analytical system that can affect
system performance may not be performed during the eight-hour (or shorter)
shift.
9.10 Calibration verification and ongoing precision and recovery: Calibration and system
performance are verified by the analysis of the 100 (jg/L PAR standard.
9.10.1 Analyze a blank (Section 9.4) and analyze the PAR standard (Section 7.12.4)
immediately thereafter at the beginning and end of each shift. Compute the
concentration of organic halide in the blank and in the PAR standard using the
procedures in Section 12. The blank shall be less than 2 jjg CI (20 pg/L
equivalent).
9.10.2 Subtract the result for the blank from the result of the PAR standard using the
procedures in Section 12, and compute the percent recovery of the blank-
subtracted PAR standard. The percent recovery shall be in the range of 78 to
116%.
9.10.3 If the recovery is within this range, the analytical process is in control and
analysis of blanks and samples may proceed. If, however, the recovery is not
within the acceptable range, the analytical process is not in control. In this
event, correct the problem and repeat the ongoing precision and recovery test
(Section 9.10), or recalibrate (Sections 10.5 through 10.6).
-------
Method 1650
9.10.4 If the recovery is not within the acceptable range for the PAR standard analyzed
at the end of the eight-hour shift, correct the problem, repeat the ongoing
precision and recovery test (Section 9.10), or recalibrate (Sections 10.5 through
10.6), and reanalyze the sample batch that was analyzed during the eight-hour
shift.
9.10.5 If the recovery is within the acceptable range at the end of the shift, and samples
are to be analyzed during the next eight-hour shift, the end of shift verification
may be used as the beginning of shift verification for the subsequent shift,
provided the next eight-hour shift begins as the first shift ends.
9.11 It is suggested but not required that the laboratory develop a statement of data quality for
AOX and develop QC charts to form a graphic demonstration of method performance.
Add results that pass the specification in Section 9.10.2 to initial and previous ongoing
data. Develop a statement of data quality by calculating the average percent recovery (R)
and the standard deviation of percent recovery (sr). Express the accuracy as a recovery
interval from R 2sr to R + 2sr. For example, if R = 95% and sr = 5%, the accuracy is 85
to 105%.
10.0 Calibration and Standardization
10.1 Assemble the OX system and establish the operating conditions necessary for analysis.
Differences between various makes and models of instruments will require different
operating procedures. Laboratories should follow the operating instructions provided by
the manufacturer of their particular instrument. Sensitivity, instrument detection limit,
precision, linear range, and interference effects must be investigated and established for
each particular instrument. Calibration is performed when the instrument is first set up
and when calibration cannot be verified (Section 9.9).
10.2 Cell performance test: Inject 100 |_iL of the sodium chloride solution (10 jjg CI ; Section
7.4) directly into the titration cell electrolyte. Adjust the instrument to produce a reading
of 10 jjg CI".
10.3 Combustion system test: This test can be used to assure that the combustion/micro-
coulometer systems are performing properly without introduction of carbon. This test
should be used during initial instrument setup and when instrument performance indicates
a problem with the combustion system.
10.3.1 Designate a quartz boat for use with the ammonium chloride (NH4C1) solution
only.
10.3.2 Inject 100 (iL of the NH4C1 solution (Section 7.5) into this boat and proceed
with the analysis.
10.3.3 The result shall be between 9.5 and 10.5 jjg CI". If the recovery is not between
these limits, the combustion or micro-coulometer systems are not performing
properly. Check the temperature of the combustion system, verify that there are
no leaks in the combustion system, confirm that the cell is performing properly
(Section 10.2), and then repeat the test.
10.4 Trichlorophenol combustion test: This test can be used to assure that the
combustion/micro-coulometer systems are performing properly when carbon is introduced.
It should be used during instrument setup and when it is necessary to isolate the adsorption
and combustion steps.
-------
Method 1650
10.4.1 Inject 10 |aL of the 1 mg/mL trichlorophenol stock solution (Section 7.12.2)
onto one level scoop of GAC in a quartz boat.
10.4.2 Immediately proceed with the analysis to prevent loss of trichlorophenol and to
prevent contamination of the carbon.
10.4.3 The result shall be between 9.0 and 11.0 (jg CI . If the recovery is not between
these limits, the combustion/micro-coulometer system shall be adjusted and the
test repeated until the result falls within these limits.
10.5 Background level of CI: Determine the average background level of CI for the entire
analytical system as follows:
10.5.1 Using the procedure in Section 11 (batch or column) that will be used for the
analysis of samples, determine the background level of CI in each of three
portions of reagent water. The volume of reagent water used shall be the same
as the volume used for analysis of samples.
10.5.2 Calculate the average (mean) concentration of CI and the standard deviation of
the concentration.
10.5.3 The sum of the average concentration plus two times the standard deviation of
the concentration shall be less than 20 pg/L. If not, the water or carbon shall be
replaced, or the adsorption system moved to an area free of organic halide
vapors, and the test (Section 10.5) shall be repeated. Only after this test is
passed may calibration proceed.
10.6 Calibration by external standard: A calibration line encompassing the calibration range is
developed using solutions of 2,4,6-trichlorophenol.
10.6.1 Analyze each of the five calibration solutions (Section 7.12.3) using the
procedure in Section 11 (batch or column) that will be used for the analysis of
samples, and the same procedure that was used for determination of the system
background (Section 10.5). Analyze these solutions beginning with the lowest
concentration and proceeding to the highest. Record the response of the micro-
coulometerto each calibration solution.
10.6.2 Prepare a method blank as described in Section 9.4. Subtract the value of the
blank from each of the five calibration results, as described in Section 12.
10.6.3 Calibration factor (ratio of response to concentration): Using the blank
subtracted results, compute the calibration factor at each calibration point, and
compute the average calibration factor and the relative standard deviation
(coefficient of variation; Cv) of the calibration factor over the calibration range.
10.6.4 Linearity: The Cv of the calibration factor shall be less than 20%; otherwise, the
calibration shall be repeated after adjustment of the combustion/micro-
coulometer system and/or preparation of fresh calibration standards.
10.6.5 Using the average calibration factor, compute the percent recovery at each
calibration point. The recovery at each calibration point shall be within the
range of 80 to 111%. If any point is not within this range, a fresh calibration
standard shall be prepared for that point, this standard shall be analyzed, and the
calibration factor (Section 10.6.3) and calibration linearity (Section 10.6.4) shall
be computed using the new calibration point. All points used in the calibration
must meet the 80 to 111% recovery specification.
-------
Method 1650
11.0 Procedure
11.1 Sample dilution: Many samples will contain high concentrations of halide. If analyzed
without dilution, the micro-coulometer can be overloaded, resulting in frequent cell
cleaning and downtime. The following guidance is provided to assist in estimating dilution
levels.
11.1.1 Paper and pulp mills that employ chlorine bleaching: Samples from pulp mills
that use a chlorine bleaching process may overload the micro-coulometer. To
prevent system overload, the maximum volume suggested paper industry
samples that employ halide in the bleaching process is 100 mL. An adsorption
volume as small as 25 mL may be used, provided the concentration of AOX in
the sample can be measured reliably, as defined by the requirements in Section
9.11. To minimize volumetric error, an adsorption volume less than 25 mL may
not be used. If AOX cannot be measured reliably in a 100-mL sample volume,
a sample volume to a maximum of 1000 mL must be used. The sample and
adsorption volumes are suggested for paper industry samples employing chlorine
compounds in the bleaching process:
Adsorp-
Sample tion
volume volume
Paper or pulp mill stream
(mL)*
(mL)
Evaporator condensate
100
100
Process water
100
100
Pulp mill effluent
30
50
Paper mill effluent
10
25
Combined mill effluent
5
25
Combined bleach effluent
1
25
C-stage filtrate
0.5
25
E-stage filtrate
0.5
25
* Assumes dilution to final volume of 100 mL. All sample
aliquots (replicates, diluted samples) must be analyzed
using the same fixed final volume (sample volume plus
reagent water, as needed).
11.1.2 Sample dilution procedure.
11.1.2.1 Partially fill a precleaned volumetric flask with pH < 2 reagent water,
allowing for the volume of sample to be added.
11.1.2.2 Mix sample thoroughly by tumbling or shaking vigorously.
11.1.2.3 Immediately withdraw the required sample aliquot using a pipet or
micro-syringe.
NOTE: Because it will be necessary to rinse the pipet or micro-syringe
(Section 11.1.2.5), it may be necessary to pre-calibrate the pipet or micro-
syringe to assure that the exact volume desired will be delivered.
11.1.2.4 Dispense or inject the aliquot into the volumetric flask.
-------
Method 1650
11.1.2.5 Rinse the pipet or syringe with small portions of reagent water and
add to the flask.
11.1.2.6 Dilute to the mark with pH < 2 reagent water.
11.1.3 All samples to be reported for regulatory compliance monitoring purposes must
be analyzed in duplicate, as described in Section 11.5.
11.1.4 Pulp and Paper in-process samples: The concentration of organic halide in-
process samples has been shown to be 20 to 30% greater using the micro-
column adsorption technique than using the batch adsorption technique. For this
reason, the micro-column technique shall be used for monitoring in-process
samples. Examples of in-process samples include: combined bleach plant
effluent, C-stage filtrate, and E-stage filtrate.
11.2 Batch adsorption and filtration.
11.2.1 Place the appropriate volume of sample (diluted if necessary), preserved as
described in Section 8, into an Erlenmeyer flask.
11.2.2 Add 5 mL of nitrate stock solution to the sample aliquot.
11.2.3 Add one level scoop of activated carbon that has passed the quality control tests
in Section 9.
11.2.4 Shake the suspension for at least one hour in a mechanical shaker.
11.2.5 Filter the suspension through a polycarbonate membrane filter. Filter by suction
until the liquid level reaches the top of the carbon.
11.2.6 Wash the inside surface of the filter funnel with 25 mL (±5 mL) of nitrate wash
solution in several portions. After the level of the final wash reaches the top of
the GAC, filter by suction until the cake is barely dry. The time required for
drying should be minimized to prevent exposure of the GAC to halogen vapors
in the air, but should be sufficient to permit drying of the cake so that excess
water is not introduced into the combustion apparatus. A drying time of
approximately 10 seconds under vacuum has been shown to be effective for this
operation.
11.2.7 Carefully remove the top of the filter holder, making sure that no carbon is lost.
This operation is most successfully performed by removing the clamp, tilting the
top of the filter holder (the funnel portion) to one side, and lifting upward.
11.2.8 Using a squeeze bottle or micro-syringe, rapidly rinse the carbon from the inside
of the filter holder onto the filter cake using small portions of wash solution.
Allow the cake to dry under vacuum for no more than 10 seconds after the final
rinse. Immediately turn the vacuum off.
11.2.9 Using tweezers, carefully fold the polycarbonate filter in half, then in fourths,
making sure that no carbon is lost.
11.3 Column adsorption.
11.3.1 Column preparation: Prepare a sufficient number of columns for one day's
operation as follows:
11.3.1.1 In a glove box or area free from halide vapors, place a plug of
Cerafelt into the end of a clean glass column.
11.3.1.2 Fill the glass column with one level scoop (approximately 40 mg) of
granular activated carbon that has passed the quality control tests in
Section 9.
-------
Method 1650
11.3.1.3 Insert a Cerafelt plug into the open end of the column to hold the
carbon in place.
11.3.1.4 Store the columns in a glass jar with PTFE lined screw-cap to prevent
infiltration of halide vapors from the air.
11.3.2 Column setup.
11.3.2.1 Install two columns in series in the adsorption module.
11.3.2.2 If the sample is known or expected to contain particulates that could
prevent free flow of sample through the micro-columns, a Cerafelt
plug is placed in the tubing ahead of the columns. If a measurement
of the OX content of the particulates is desired, the Cerafelt plug can
be washed with nitrate solution, placed in a combustion boat, and
processed as a separate sample.
11.3.3 Adjusting sample flow rate: Because the flow rate used to load the sample onto
the columns can affect the ability of the GAC to adsorb organic halides, the flow
rate of the method blank is measured, and the gas pressure used to process
samples is adjusted accordingly. The flow rate of the blank, which is composed
of acidified reagent water and contains no particulate matter, should be greater
than the flow rate of any sample containing even small amounts of particulate
matter.
11.3.3.1 Fill the sample reservoir with the volume of reagent water chosen for
the analysis (Section 9.4.1.2) that has been preserved and acidified as
described in Section 8. Cap the reservoir.
11.3.3.2 Adjust the gas pressure per the manufacturer's instructions. Record
the time required for the entire volume of reagent water to pass
through both columns. The flow rate must not exceed 3 mL/min over
the duration of the time required to adsorb the volume. If this flow
rate is exceeded, adjust gas pressure, prepare another blank, and
repeat the adsorption.
11.3.3.3 Once the flow rate for the blank has been established, the same
adsorption conditions must be applied to all subsequent samples
during that eight-hour shift, or until another method blank is
processed, whichever comes first. To aid in overcoming breakthrough
problems, a lower gas pressure (and, therefore, flow rate) may be
used for processing of samples, if desired. If the sample adsorption
unit is disassembled or cleaned, the flow rate must be checked before
processing additional samples.
11.3.3.4 Elute the pair of columns with 2 mL of nitrate wash solution. The
flow rate of nitrate wash solution must not exceed 3 mL/min.
11.3.3.5 Separate the columns and mark for subsequent analysis.
11.3.4 The adsorption of sample volumes is performed in a similar fashion. Fill the
sample reservoir with the sample volume chosen for the analysis (Section 11.1),
that has been preserved as described in Section 8. All analyses must be
performed with this volume (sample volume plus reagent water, as needed) in
order to maintain a flow rate no greater than that determined for the blank (see
Section 11.3.3).
-------
Method 1650
11.3.4.1 Use the same gas pressure for sample adsorption as is used for the
blank.
11.3.4.2 Elute the columns with 2 mL of the nitrate wash solution.
11.3.4.3 Separate the columns and mark for subsequent analysis.
11.3.5 If it is desirable to make measurements at levels lower than can be achieved with
the sample volume chosen, or if the instrument response of an undiluted sample
is less than three times the instrument response of the blank (Section 12.6.3), a
larger sample volume must be used.
11.4 Combustion and titration.
11.4.1 Polycarbonate filter and GAC from batch adsorption.
11.4.1.1 Place the folded polycarbonate filter containing the GAC in a quartz
combustion boat, close the airlock, and proceed with the automated
sequence.
11.4.1.2 Record the signal from the micro-coulometer for a minimum
integration time of 10 minutes and determine the concentration of CI
from calibration data, per Section 12.
11.4.2 Columns from column adsorption.
11.4.2.1 Using the push rod, push the carbon and the Cerafelt plug(s) from the
first column into a combustion boat. Proceed with the automated
sequence.
11.4.2.2 Record the signal from the micro-coulometer for a minimum
integration time of 10 minutes and determine the concentration of CI
for the first column from calibration data, per Section 12.
11.4.2.3 Repeat the automated sequence with the second column.
11.4.2.4 Determine the extent of breakthrough of organic halides from the first
column to the second column, as described in Section 12.
11.4.3 The two columns that are used for the method blank must be combusted
separately, as is done for samples.
11.5 Duplicate sample analysis: All samples to be reported for regulatory compliance purposes
must be analyzed in duplicate. This requirement applies to both the batch and column
adsorption procedures. In addition, if it is necessary to dilute the sample for the purposes
of reducing breakthrough or maintaining the concentration within the calibration range, a
more or less dilute sample must be analyzed. The adsorption volumes used for analysis of
undiluted samples, diluted samples, and all replicates must be the same as the volume used
for QC tests and calibration (Sections 9 and 10).
11.5.1 Using results from analysis of one sample volume (Section 11.4) and the
procedure in Section 11.1.2, determine if the dilution used was within the
calibration range of the instrument and/or if breakthrough exceeded the
specification in Section 12.3.1. If the breakthrough criterion was exceeded or
the sample was not within the calibration range, adjust the dilution volume as
needed. If the breakthrough criterion was not exceeded and the sample dilution
was within the calibration range, a second volume at the same dilution level may
be used.
-------
Method 1650
11.5.2 Adsorb the sample using the same technique (batch or column) used for the first
sample volume. Combust the GAC from the second volume as described in
Section 11.4, and calculate the results as described in Section 12. Compare the
results of the two analyses as described in Section 12.4.
11.5.3 Duplicate analyses are not required for method blanks, as different dilution
levels are not possible.
11.5.4 Duplicate analyses of the PAR standard used for calibration verification
(Section 9.10) are not required.
12.0 Data Analysis and Calculations
12.1 Batch Adsorption Method: Calculate the blank-subtracted concentration of adsorbable
organic halide detected in each sample (in micrograms of chloride per liter) using the
following equation:
(iig/L) = (C yB)
where:
C = \ig CI ~ from micro - coulometer for the sample
B = \ig CI ~ from micro - coulometer for the reagent water blank (Section 9.4.1)
V = volume of sample in liters
This calculation is performed for each of the two dilution levels analyzed for each sample.
12.2 Column Adsorption Method: Calculate the blank-subtracted concentration of adsorbable
organic halide detected in each sample (in micrograms of chloride per liter) using the
following equation:
[ (C"i + C2) ~(B1 + B2) ]
vhere:
"i
AOX (\iglL)
V
"2
= (ig CI from micro - coulometer for first column from the sample
= \ig Cr from micro - coulometer for second column from the sample
from micro - coulometer for first column from the reagent water blank (Section 9.4.1)
32 = (ig Cr from micro - coulometer for second column from the reagent water blank (Section 9.4.1
^ = volume of sample in liters
12.3 Percent breakthrough: For each sample analyzed by the column method, calculate the
percent breakthrough of halide from the first column to the second column, using the
following equation:
(C2 - b2)( 100)
% Breakthrough
[(Cj - Bx)+{C2 - B2)\
12.3.1 For samples to be reported for regulatory compliance purposes, the percent
breakthrough must be less than or equal to 25% for both of the two analyses
performed on each sample (see Section 11.5).
-------
Method 1650
12.3.2 If the breakthrough exceeds 25%, dilute the affected sample further, maintaining
the amount of halide at least three times higher than the level of blank, and
reanalyze the sample. Ensure that the sample is also analyzed at a second level
of dilution that is at least a factor of 2 different (and still higher than three times
the blank).
12.4 Relative percent difference (RPD): Calculate the relative percent difference between the
results of the two analyses of each sample, using the following equation:
2001(AOX, - AOX0)\
RPD = ! —
[(AOXl + AOX2)]
12.5 High concentrations of AOX: If the amount of halide from either analysis exceeds the
calibration range, dilute the sample and reanalyze, maintaining at least a factor of 2
difference in the dilution levels of the two portions of the sample used.
12.6 Low concentrations of AOX: The blank-subtracted final result from the batch procedure or
the sum of the blank-subtracted results from the two carbon columns should be
significantly above the level of the blank.
12.6.1 If the instrument response for a sample exceeds the instrument response for the
blank by a factor of at least 3, the result is acceptable.
12.6.2 If the instrument response for a sample is less than three times the instrument
response for the blank, and the sample has been diluted, analyze a less dilute
aliquot of sample.
12.6.3 If the instrument response of an undiluted sample containing AOX above the
minimum level is less than three times the instrument response for the blank, the
result is suspect and may not be used for regulatory compliance purposes. In
this case, find the cause of contamination, correct the problem, and reanalyze the
sample under the corrected conditions.
12.7 Report results that meet all of the specifications in this method as the mean of the blank-
subtracted values from Section 12.1 or 12.2 for the two analyses at different dilution
levels, in (jg/L of CI (not as 2,4,6-trichlorophenol), to three significant figures. Report the
RPD of the two analyses. For samples analyzed by the column procedure, also report the
percent breakthrough.
13.0 Method Performance
The specifications contained in this method are based on data from a single laboratory and from a
large-scale study of the pulp and paper industry.
14.0 Pollution Prevention
14.1 The solvents used in this method pose little threat to the environment when recycled and
managed properly.
14.2 Standards should be prepared in volumes consistent with laboratory use to minimize the
volume of expired standards to be disposed.
-------
Method 1650
15.0 Waste Management
15.1 It is the laboratory's responsibility to comply with all federal, state, and local regulations
governing waste management, particularly the hazardous waste identification rules and
land disposal restrictions, and to protect the air, water, and land by minimizing and
controlling all releases from fume hoods and bench operations. Compliance with all
sewage discharge permits and regulations is also required.
15.2 Samples preserved with HC1 or H2S04 to pH < 2 are hazardous and must be neutralized
before being disposed, or must be handled as hazardous waste. Acetic acid and silver
acetate solutions resulting from cell flushing must be disposed of in accordance with all
applicable federal, state, and local regulations.
15.3 For further information on waste management, consult "The Waste Management Manual
for Laboratory Personnel", and "Less is Better: Laboratory Chemical Management for
Waste Reduction," both available from the American Chemical Society's Department of
Government Relations and Science Policy, 1155 16th Street N.W., Washington, D.C.
20036.
-------
Method 1650
16.0 References
16.1 "Total Organic Halide, Methods 450.1—Interim," Prepared by Stephen Billets and James
J. Lichtenberg, USEPA, Office of Research and Development, Physical and Chemical
Methods Branch, EMSL-Cincinnati, Cincinnati, OH 45268, EPA 600/4-81-056 (1981).
16.2 Method 9020, USEPA Office of Solid Waste, "Test Methods for Evaluating Solid Waste,
SW-846," Third Edition, 1987.
16.3 "Determination of Adsorbable Organic Halogens (AOX)," "German Standard Methods for
the Analysis of Water, Waste Water and Sludge—General Parameters of Effects and
Substances," Deutsche Industrie Norm (DIN) Method 38 409, Part 14, DIN German
Standards Institute, Beuth Verlag, Berlin, Germany (1987).
16.4 "Water Quality—Determination of Adsorbable Organic Halogens (AOX)," International
Organization for Standard/Draft International Standardization (ISO/DIS) Method 9562
(1988).
16.5 "Organically Bound Chlorine by the AOX Method," SCAN-W 9:89, Secretariat,
Scandinavian Pulp, Paper and Board Testing Committee, Box 5604, S-11486, Stockholm,
Sweden (1989).
16.6 Method 5320, "Dissolved Organic Halogen," from "Standard Methods for the Examination
of Water and Wastewater," 5320, American Public Health Association, 1015 15th St.
NW, Washington, DC 20005 (1989).
16.7 "Canadian Standard Method for the Determination of Adsorbable Organic Halides (AOX)
in Waters and Wastewaters," Environment Canada and The Canadian Pulp and Paper
Association (1990).
16.8 40 CFRPart 136, Appendix B.
16.9 "Working with Carcinogens," DHEW, PHS, CDC, NIOSH, Publication 77-206, (Aug
1977).
16.10 "OSHA Safety and Health Standards, General Industry" OSHA 2206, 29 CFR 1910 (Jan
1976).
16.11 "Safety in Academic Chemistry Laboratories," ACS Committee on Chemical Safety
(1979).
16.12 "Methods 330.4 and 330.5 for Total Residual Chlorine," USEPA, EMSL-Cincinnati,
Cincinnati, OH 45268, EPA-4-79-020 (March 1979).
16.13 "Validation of Method 1650: Determination of Organic Halide," Analytical Technologies
Inc., ERCE Contract 87-3410, November 15, 1990. Available from the EPA Sample
Control Center, DynCorp, 300 N. Lee St, Alexandria, VA 22314 (703-519-1140).
17.0 Diagrams
-------
Method 1650
a. Mtsubishi
b. Dohmann
c. Euroglas
<5L
Silver
Sensor
Electrode
Silver/Silver
Oilo ride
Reference"
Electrode
\ !
!
|
¥.
1
fy:
1 n
1
m
m
ik&i
Stirrer
Rati riu rn
" Bectrode
Silver
"Generator
Electrode
Silver/Silver
Acetato
Reference
Electrode
Silver
Sensor
Bectrode
Silver
Generator
Bectrode
Platinum
Electrode
Silver
Generator
Bectrode
Gases In
Platinum
Electrode
No Stirrer
Slver
Sensor
Beclrode
Silver/Silver
Chloride
Reference
Electrode
Figure 1. Microcoulometric Titration Cells (from Reference 7)
-------
Method 1650
Funnel
G lamp
Slain less-
Steel Support
PTFE Gasket
O
Base
No. 5
Stopper.
Figure 2. Filter Apparatus
5s-o»im
-------
Method 1650
N itrate Wash
Reservoir
Figure 3. Schematic of the Column Adsorption System
-------
Method 1650
1.
Stripping Device
2.
Sample inlet for AOX
3.
AOX Sample
4.
Furnace
5.
Combustion Tube
e.
A bsorber filled wiih H4SO+
7.
Tltratb n ce II
e.
Working electrodes
9.
Measuring electrodes
10.
Stirrer
11.
Titration micro -processor
12.
Gas flow and tern pe latu re contro I device
Si-OSfriftl
Figure 4. Schematic of an AOX Apparatus
-------
Method 1650
18.0 Glossary of Definitions and Purposes
These definitions and purposes are specific to this method but have been conformed to
common usage as much as possible.
18.1 Units of weight and measure and their abbreviations.
18.1.1 Symbols
°C degrees Celsius
jug microgram
, L microliter
< less than
> greater than
% percent
18.1.2 Alphabetical characters
cm centimeter
g gram
h hour
ID inside diameter
in inch
L liter
m meter
mg milligram
min minute
mL milliliter
mm millimeter
N normal; gram molecular weight of solute divided by hydrogen
equivalent of solute, per liter of solution
OD outside diameter
ppb part-per-billion
ppm part-per-million
ppt part-per-trillion
psig pounds-per-square inch gauge
v/v volume per unit volume
w/v weight per unit volume
18.2 Definitions and acronyms (in alphabetical order).
Analyte—AOX tested for by this method.
Calibration standard (CAL)—A solution prepared from a secondary standard
and/or stock solution which is used to calibrate the response of the instrument
with respect to analyte concentration.
Calibration verification standard (VER)—The mid-point calibration standard
(CS3) that is used to verify calibration.
Field blank—An aliquot of reagent water or other reference matrix that is placed
in a sample container in the laboratory or the field, and treated as a sample in all
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respects, including exposure to sampling site conditions, storage, preservation,
and all analytical procedures. The purpose of the field blank is to determine if
the field or sample transporting procedures and environments have contaminated
the sample.
IPR—Initial precision and recovery; four aliquots of the diluted PAR standard
analyzed to establish the ability to generate acceptable precision and accuracy.
An IPR is performed prior to the first time this method is used and any time the
method or instrumentation is modified.
Laboratory blank—See Method blank.
Laboratory control sample (LCS)—See Ongoing precision and recovery sample
(OPR).
Laboratory reagent blank—See Method blank.
May—This action, activity, or procedural step is neither required nor
prohibited.
May not—This action, activity, or procedural step is prohibited.
Method blank—An aliquot of reagent water that is treated exactly as a sample
including exposure to all glassware, equipment, solvents, reagents, internal
standards, and surrogates that are used with samples. The method blank is used
to determine if analytes or interferences are present in the laboratory
environment, the reagents, or the apparatus.
Minimum level (ML)—The level at which the entire analytical system must give
a recognizable signal and acceptable calibration point for the analyte. It is
equivalent to the concentration of the lowest calibration standard, assuming that
all method-specified sample weights, volumes, and cleanup procedures have
been employed.
Must—This action, activity, or procedural step is required.
OPR—Ongoing precision and recovery standard; a laboratory blank spiked with
a known quantity of analyte. The OPR is analyzed exactly like a sample. Its
purpose is to assure that the results produced by the laboratory remain within
the limits specified in this method for precision and recovery.
PAR—Precision and recovery standard; secondary standard that is diluted and
spiked to form the IPR and OPR.
Preparation blank—See Method blank.
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Primary dilution standard—A solution containing the specified analytes that is
purchased or prepared from stock solutions and diluted as needed to prepare
calibration solutions
and other solutions.
Quality control check sample (QCS)—A sample containing all or a subset of the
analytes at known concentrations. The QCS is obtained from a source external
to the laboratory or is prepared from a source of standards different from the
source of calibration standards. It is used to check laboratory performance with
test materials prepared external to the normal preparation process.
Reagent water—Water demonstrated to be free from the analyte of interest and
potentially interfering substances at the method detection limit for the analyte.
Relative standard deviation (RSD)—The standard deviation multiplied by 100,
divided by the mean.
RSD—See Relative standard deviation.
Should—This action, activity, or procedural step is suggested but not required.
Stock solution—A solution containing an analyte that is prepared using a
reference material traceable to EPA, the National Institute of Science and
Technology (NIST), or a source that will attest to the purity and authenticity of
the reference material.
VER—See Calibration verification standard.
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