Method 1649 Draft May 1991
Organic Halides in Solid Matrices by Coulometric Titration
1 Scope and application
1.1 This method is designed to meet the
survey requirements of the United
States Environmental Protection
Agency (EPA). It is used to
determine organic hat ides associated
with the Clean Water Act; the
resources Conservation and Recovery
Act; the Comprehensive Environmental
Response, Compensation and Liability
Act; and other organic halidcs
amenable to combustion and
Coulometric titration.
1.2 The method is applicable to the
determination of organic halides in
soils, sludges, and pulp. The method
is a combination of existing methods
and new technology for organic halide
measurement.
1.3 This method is for use by or under
the supervision of analysts
experienced in the use of a
combustion/microcoulometer. Each
laboratory that uses this, method must
demonstrate the ability ,to generate
acceptable results using the
procedure in Section 8.2.
1.4 Any modification of this method
beyond those expressly permitted
(Section 8.1.2) is subject to the
application and approval of alternate
test procedures under 40 CFR Parts
134 and 135.
2 Summary of Method
2.1 Sample preparation: organic halides
are leached from the sample into
water by acidification and
sonication. The organic halidcs in
the leachatc are adsorbed onto
granular activated carbon (GAC). The
sample and GAC are collected on a
polycarbonate filter.
2.2 Sample analysis--Commbustion/micro-
coulometric: the sample, GAC, and
filter are combusted to form the
hydrogen halide, and titration of the
hydrogen halide with a
microcoulometer, as shown in Figure
3. The 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, it is
partitioned into the 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.
2.3 The mass concentration of organic
halidcs is reported as an equivalent
concentration of organically bound
chloride (CO.
3 Contamination and interferences
3.1 Solvents, reagents, glassware, and
other sample processing hardware may
yield elevated readings from the
microcoulometer. 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 set (samples started through
the adsorption process in a given 8
hour shift, to a maximum of 20
samples). Specific selection of
reagents and purification«of solvents
may be required.
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3.2 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 fewer cleaning steps show
no detectable organic halide, the
cleaning steps from above that do not
eliminate organic halide may be
omitted.
3.3 Host 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.
3.4 Activated carbon
3.4.1 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 8.5). 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.
3.4.2 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.
3.4.3 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.
3.5 Polyethylene gloves should be worn
when handling equipment surfaces in
contact with the sample.
4 Safety
4.1 The toxicity or carcinogenic!ty of
each reagent used in this method has
not been precisely determined;
however, each chemical substance
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 should be available to
all personnel involved in the
chemical analysis. Additional
information on laboratory safety can
be found in references 9-11.
*
4.2 This method employs strong acids.
Appropriate clothing, gloves, and eye
protection should be worn when
handling these substances.
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4.3 Field samples may contain high
concentrations of toxic volatile
compounds. Sample containers should
be opened in a hood and handled with
gloves that uill prevent exposure.
5 Apparatus and materials
5.1 Sampling equipment
5.1.1 4 ounce glass jar-- Chromic acid
rinse, detergent water wash, rinse
with tap and distilled water, cover
with aluminum foil and heat to 450 °C
for at least one hour before use.
5.1.2 Teflon liner—cleaned as above and
baked at 100 - 200 °C for at least
one hour.
5.1.3 Jars and liners must be lot certified
to be free of organic ha I ides by
running blanks according to this
method.
5.2 Scoop of granular activated carbon
(GAC)--capable of precisely measuring
0.13 «•/- 0.01 cc GAC (Dohrmann
Measuring Cup 521-021, or
equivalent). This scoop size has
been shown to hold 35 - 60 mg of GAC,
depending on the carbon source. The
variance in GAC mass has been shown
to have no affect on method
performance (Reference 13).
5.3 Adsorption apparatus
5.3.1 Finger type sonicator capable of
developing 100-110 watts at 50% duty-
Cycle. (Branon Model 450 or
equivalent)
5.3.2 20 ml vials used for sample
sonication.
5.3.3 Adsorption system--rotary shaker,
wrist action shaker, or other system
for assuring thorough contact of
sample with activated carbon. The
system used shall be demonstrated to
meet the performance requirements in
Section 8 of this method.
5.3.3.1 Erlenmeyer flasks--250 with ground
glass stopper, for use with rotary
shaker.
5.3.3.2 Shake table--Sybron Thermolyne Model
LE "Big Bill" rotator/shaker, or
equivalent.
5.3.3.3 Rack attached to shake table to
permit agitation of 16 - 25 samples
simultaneously.
5.3.4 Filtration system-- Figure V
5.3.4.1 Vacuum filter holder—glass, with
fritted glass support (Fisher Model
09-753E, or equivalent).
5.3.4.2 Poly carbonate filter--0.45 micron,
25 mm diameter, (Micro Separation
Inc. Model K04CP02500, or
equivalent).
5.3.4.3 Filter forceps—Fisher Model 09-753-
50, or equivalent, for handling
filters. Clean by washing with
detergent and water, rinsing with tap
and deionized water, and air drying
on aluminum foil. Two forceps may
better aid in handling filters.
Clean by washing with detergent and
water, rinsing with tap and dcionized
water, and air drying on aluminum
foil.
5.3.4.4 Vacuum flask—500 mL (Fisher 10-1800,
or equivalent).
5.3.4.5 Vacuum Source--a pressure/vacuum
pump, rotary vacuum pump, or other
vacuum source capable of"providing at
least 610 mm (24 in) Hg vacuum and 30
L/min free air displacement.
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5.3.4.6 Stopper and tubing to mate the filter
holder to the flask and the flask to
the pump.
5.3.4.7 Polyethylene gloves--(Fisher 11-394-
110-B, or equivalent).
5.4
5.4.1
5.4.1.1
Figure 1 Filter apparatus
Combusti on/mi cro-coulometer system--
commercial ly available as a single
unit or assembled from parts. At the
time of writing this method, organic
halide units were commercially
available from Oorhmann Division of
Rosemount Analytical, Santa Clara,
California: Euroglas BV, Delft, the
Netherlands; and Mitsubishi Chemical
Industries Ltd., Tokyo, Japan
Combustion system--older systems may
not have all of the features shown in
Figure 3. These older systems may be
used provided the performance
requirements (Section 8) of this
method are met.
Combustion tube—quartz, capable of
being heated to 800 - 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.
5.4.1.2 Tube furnace capable of controlling
combustion tube in the range of 800 -
1000 °C.
5.4.1.3 Boat sampler -- capable of holding
the 50 mg of sample, 35 - 60 mg of
GAC and a polycarbonate filter as
well as fitting into the tube
(5.4.1.1). 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 organic material in the boat is
burned in a flowing oxygen stream.
The evolved gases are transported by
a nonreactive carrier gas to the
microcoulometer cell.
5.5.1.4 Motor driven boat samplei—capable of
advancing the combustion boat into
the furnace in a reproducible time
sequence. A time sequence shown to
be effective is:
A. Establish initial gas flow rates:
160 ml/min C02; 40 ml/min 02-
B. Sequence start.
C. Hold boat in hatch for 5 seconds
to allow integration for baseline
subtraction.
0. Advance boat into vaporization
zone.
E. Hold for 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 pyrolysTs zone for 6
minutes.
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H. Return gas flow rates to initial
values; retract boat into hatch to
cool and to allow remaining HX to be
swept into detector (approx 2
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.
5.4.1.5 Absorber—containing sulfuric acid to
dry the gas stream after combustion
to prevent backflush of electrolyte
is recommended.
5.4.2 Hicrocoulometer system—capable of
detecting the equivalent of 1 ug of
Cl- with a relative standard
deviation of less than 10 percent,
and capable of accumulating a minimum
of the equivalent of 500 ug of Cl-
before a change of electrolyte is
required.
5.4.2.1 Micro-coulometer cell — the three cell
designs presently in use are shown in
Figure 2. Cell operation is
described in Section 2.
accumulating and displaying the
charge produced by hydrogen halides
entering the cell. A strip chart
recorder is desirable for display of
accumulated charge.
1 ? 3 5
Figure 3: Schematic of an AOX
apparatus
1. Stripping Device
2. Sample inlet for AOX
3. AOX sample
4. Furnace
5. Combustion Tube
6. Absorber filled with H2S04
7. Titration cell
8. Working electrodes
9. Measuring electrodes
10. Stirrer
11. Titration micro processor
12. Gas flow and temperature control
device
> i
Figure 2 Microcoulometric titration
cells [from Ref (7)]
5.4.2.2 Cell controller— electronics capable
of measuring the small currents
generated in the cell and
5.6 Miscellaneous glassware
5.6.1 Volumetric flasks-5, 10, 25, 50,
100, and 1000mL
5.6.2 Beakers — 100, 500, and 1000 mL
5.6.3 Volumetric pipets—1 and 10 ml with
pipet bulbs
5.6.4 Volumetric micro-pipets—,10, 20, 50,
100, 200, and 500 ul with pipet
control (Hamilton 0010, or
equivalent)
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5.6.5 Graduated cylinders—ID, 100,
1000 ml
and
5.7 Micro-syringes--10, 50, and 100 uL
5.8 Balances
5.8.1 Top loading, capable of weighing 0.1
gram
5.8.2 Analytical, capable of weighing 0.1
mg
5.9
6.1
Wash bottles--500
or polyethylene
1000 mi, Teflon
Reagents and standards
Granular activated carbon (GAO--75 -
150 urn (100 to 200 mesh), (Oorhmann
511-877, or equivalent), with
chlorine content less than 1 ug Cl-
per scoop (<25 ug Cl- per gram),
adsorption capacity greater than 1000
ug Cl- (2,4,6-trichlorophenol) per
scoop (>25,000 ug per gram),
inorganic halide retention of less
than 1 ug Cl- per scoop in the
presence of 2500 mg of inorganic
halide), and that meets the other
test criteria in Section 8.5 of this
method.
6.2 Reagent water—water in which organic
halide is not detected by this
method.
6.2.1 Preparation—reagent water may be
generated by:
6.2.1.1 Activated carbon—pass tap water
through a carbon bed (Calgon
Filtrasorb-300, or equivalent).
6.2.1.2 Water purifier —pass tap water
through a purifier (Hillipore Super
0, or equivalent).
6.2.2 pH ajustment —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 (6.8.6).
6.3 Nitric acid (HNOj)—concentrated,
analytical grade
6.4 Nitrate stock solution—in a 1000 ml
volumetric flask, dissolve 17 g of
NaN03 in approx 100 ml of water, add
1.4 mL nitric acid (Section 6.3) and
dilute to the mark with reagent
water.
6.5 Nitrate wash solution—dilute 50 ml
of nitrate stock solution (Section
6.4) to 1000 mL with reagent water.
6.6 Sodium thiosulfate (Na2S203) solution
(1 N)—weigh 79 grams Na2S203 in a 1
liter volumetric flask and dilute to
the mark with reagent water.
6.7 Trichlorophenol solutions
6.7.1 Trichlorophenol stock solutions (1.0
mg/mL of Cl-)—dissolve 0.186 g of
2,4,6-trichlorophenol in 100 ml of
halide-free methanol.
6.7.2 Trichlorophenol precision and
recovery standard—place 50 mg of
quartz sand in a 20 ml vial and add
100 uL of trichlorophenol stock
solution (6.7.1).
6.8 Reagents and standards for combustion
system
6.8.1 Sodium chloride (NaCl) solution—(100
ug/L of Cl-)—dissolve 0.165g NaCl in
1000 ml reagent water. This solution
is used for cell testing and for the
inorganic halide rejection test.
6.8.2 Ammonium chloride (NH^Cl) solution
(100 ug/mL of Cl-)—dis&olve 0.165 g
NH^Cl in 1000 ml reagent water.
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6.8.3 Sulfuric acid—reagent grade
(specific gravity 1.84)
6.8.4 Oxygen--99.9X purity
6.8.5 Carbon Dioxide--99.9X purity
6.8.6 Acetic acid solution—containing 30 -
70 percent acetic acid in deionized
water per the instrument
manufacturers instructions.
7 Calibration
7.1 Assemble the OX system and establish
the operating conditions necessary
for analysis. Differences between
various makes and models of
instruments will require differing
operating procedures. Analysts
should follow the operating
instructions provided by the
manufacturer of their particular
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
set up and when calibration cannot be
verified (Section 11).
7.2 Cell performance test--inject 100 uL
of the sodium chloride solution (10
ug of CI-; Section 6.8.1) directly
into the titration cell electrolyte.
Adjust the instrument to produce a
reading of 10 ug CI-.
7.3 Combustion system test — this test can
be used to assure that the
combustion/micro-coulometer systems
are performing properly without
introduction of carbon. It should be
used during instrument setup and when
instrument performance indicates a
problem with the combustion system.
Check the temperature of the
combustion system and verify that
there are no leaks in the combustion
system end that
performing properly
then repeat the test.
the cell is
(Section 7.2),
7.3.1 Designate a quartz boat for use with
the amnonium chloride (NH^Cl)
solution only.
7.3.2 Inject 100 uL of the NH^Cl solution
(6.8.2) into this boat and proceed
with the analysis.
7.3.3 The result shall be between 9.5 and
10.5 ug Cl". 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
and verify that the cell is
performing properly (Section 7.2),
then repeat the test.
7.4 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.
7.4.1 Inject 10 uL of the 1 mg/mL
trichlorophenol calibration solution
(6.7.1) onto one level scoop of GAG
in a quartz boat.
7.4.2 Immediately proceed with the analysis
to prevent loss of trichlorophenol
and to prevent contamination of the
carbon.
7.4.3 The result shall be between 9.0 and
11.0 ug Cl". 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.
7.5 Background level of Cl- —determine
the average background l-evel of Cl-
for the entire analytical system as
follows:
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7.5.1 Using the procedure in Section 10
that will be used for the analysis of
samples, determine the background
level of Cl- in each of three 10 mg
portions of quartz sand.
7.5.2 Calculate the average (mean)
concentration of Cl- and the standard
deviation of the concentration.
7.5.3 The sun of the average concentration
plus two times the standard deviation
of the concentration shall be less
than 2 ug. 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 (7.5) shall be repeated.
Only after this is passed may
calibration proceed.
7.6 Calibration by external standard—a
calibration curve encompassing the
calibration range is performed using
2,4,6-trichlorophenol.
7.6.1 Place 50 mg of quartz sand in each of
five 20 ml vials.
7.6.2 Pipet 20, 50, 100, 300. and 800 uL of
trichlorophenol stock . solution
(6.7.1) into the vials from 7.6.1.
Some instruments may have a
calibration range that does not
-extend to 80 ug of Cl-. For those
instruments, a less 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.
7.6.3 Proceed with the analysis of each
sample as per Section 10.
7.6.4 Using the calculations in Section
12.1 determine the halide present in
each standard.
7.6.5 Subtract the average value of the
background (Section 7.5.2) from each
of the five determinations.
7.6.6 Calibration factor (ratio of response
to concentrat ion)--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.
7.6.7 Linearity—the Cv of the calibration
factor shall be less than 20 percent;
otherwise, the calibration shall be
repeated after system corrections
have been made
8 Quality assurance/quality control
8.1 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 (HS/HSO) samples to
assess accuracy and precision.
Laboratory performance is compared to
establish performance criteria to
determine if the results of analyses
meet the performance characteristics
of the method.
8.1.1 The analyst shall make an initial
demonstration of the ability to
generate acceptable accuracy and
precision with this me.thod. This
ability is demonstrated as described
in Section 8.2. •
8.1.2 The analyst is permitted to modify
this method to improve performance or
DRAFT
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lower the costs of measurements
provided all performance
specifications are met. Each time a
modification is made to the method,
the analyst is required to repeat the
procedures in Sections 7.2 to 7.6 and
Section 8.2 to demonstrate method
performance.
8.1.3 The laboratory shall spike 10 percent
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 8.3. When results of these
spikes indicate atypical method
performance for samples, the samples
are diluted to bring method
performance within acceptable limits.
8.1.4 Analyses of blanks are required to
demonstrate freedom from
contamination. The procedures and
criteria for analysis of a blank are
described in Section 8.4.
8.1.5 The laboratory shall, on an on-going
basis, demonstrate through the
analysis of the precision and
recovery standard that the analysis
system is in control. These
procedures are described in Section
11. f.
8.1.6 The laboratory shall perform quality
control tests on the granular
activated carbon. These procedures
are described in Section 8.5
8.2 Initial precision and recovery (IPR)-
-to establish the ability to generate
acceptable precision and recovery,
the analyst shall perform the
following operations.
8.2.1 Analyze four PAR standards (Section
6.7.2) according to the procedure in
Section 10.
8.2.2 Using the 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.
8.2.3 The average percent recovery shall be
in the range of 7.7 - 10.8 ug and the
standard deviation shall be less than
0.7 ug. 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.
8.3 Matrix spikes--the laboratory shall
spike a minimum of 10 percent of
samples from a given matrix type
(e.g., soil, sludges, and pulps) in
duplicate (MS/HSO). If only one
sample from a given matrix type is
analyzed, an additional two aliquots
of that sample shall be spiked.
8.3.1 The concentration of the analytes
spiked into the MS/USD shall be
determined as follows:
8.3.1.1 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
8.3.2, whichever concentration is
higher. *
8.3.1.2 If the concentration of OX is not
being checked against a regulatory
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limit, the spike shall be at the
concentration of the PAR standard
(Section 6.7.2) or at one to five
times higher than the background
concentration determined in Section
8.3.2, whichever concentration is
higher.
8.3.2 Analyze one sample out of each set of
10 samples from each matrix to
determine the background
concentration (8) of OX. Spike two
additional sample aliquots with
spiking solution and analyze them to
determine the concentration after
spiking (A).
8.3.2.1 Compute the percent recovery (P) of
each analyte in each aliquot:
P = 100 (A - B)/T
where T is the true value of the
spike.
8.3.2.2 Compute the relative percent
difference (RPO) between the two
results (not between the two
recoveries):
RPD = | 2CA1 - A2) |/(A1 + A2)
8.3.2.3 If the RPO is less than 20 percent,
and the recoveries for the MS and USD
are within the range of 71 - 116
percent, the results are acceptable.
8.3.2.4 If the RPO is greater than 20
percent, analyze two aliquots of the
precision and recovery standard
(PAR).
8.3.2.4.1 If the RPD for the two aliquots of
the PAR is greater than 20 percent,
the analytical system is out of
control. In this case, repair the
problem and repeat the analysis of
the sample set, including the MS/HSD.
8.3.2.4.2 If, however, the RPD for. the two
aliquots of the PAR is less than 20
percent, dilute the sample chosen for
the MS/HSO by a factor of 10 and
repeat the MS/HSO test. If the RPO
is still greater than 20 percent, the
result may not be reported for
regulatory compliance purposes. In
this case, choose another sample for
the HS/HSO and repeat analysis of the
sample set.
8.3.2.5 If the percent recovery for both the
MS and MSO are less than 71 or
greater than 116 percent, analyze the
precision and recovery (PAR)
standard. '
8.3.2.5.1 If the recovery of the PAR is outside
the 71 - 116 percent range, the
analytical system is out of control.
In this case, repair the problem and
repeat the analysis of the sample
set, including the MS/HSO.
8.3.2.5.2 If the recovery of the PAR is within
the range of 71 - 116 percent, dilute
the sample, MS, and MSO by a factor
of 10 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/MSO and repeat the analysis of
the sample set.
8.4 Blanks—reagent water blanks are
analyzed to demonstrate freedom from
contamination.
8.4.1 Analyze a reagent water blank with
each set of samples. The blank must
be analyzed immediately following
calibration verification to
demonstrate freedom from
contamination and memory effects and
must include all details of the
procedure to be followed when
analyzing samples.
*
8.4.2 If more than 2 ug is found in the
blank, analysis of samples is hatted
until the source of contamination is
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10
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eliminated and a blank shows no
evidence of contamination at this
level.
8.5 Granular activated carbon (GAC)
testing—each batch of activated
carbon is tested before use to ensure
adequate quality. Use only GAC that
meets the test criteria below.
8.5.1 Contamination test — analyze a scoop
of GAC. Reject carbon if the amount
of OX exceeds 1 ug (25 ug CI-/9)
8.5.2 Inorganic chloride adsorption test--
attempt to adsorb NaCl from 100 mg/l
in reagent water. Wash with nitrate
solution and analyze. The amount of
halide should be less than 1 ug Cl-
larger than the blank. A larger
amount indicates significant uptake
of inorganic chloride by the carbon.
Reject carbon if the 1 ug level is
exceeded.
'i
8.5.3 Carbon capacity test—prepare an
adsorption test standard solution in
reagent water to contain 10 mg/l
organic carbon (as humic acids of
equivalent) and an organic halide
concentration of 100 ug/L organo-
chloride (from 2,4,6-
trichlorophenol). Prepare a blank
solution containing only the 10 mg
organic carbon. Analyze 100 ml
portions of these solutions.
Subtract the result of the blank from
the result of the halide spike,
compare the blank subtracted result
to the true value of the spike.
Recovery of the halide should be
greater than 85 percent.
8.6 The specifications contained 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 7), calibration verification
(Section 11), and for the initial
(Section 8.2) and ongoing (Section
11) precision and recovery should be
identical, so that the most precise
results will be obtained.
8.7 Depending on specific program
requirements, field duplicates may be
collected to determine the precision
of the sampling technique.
9 Sample collection and preservation
9.1
9.2
9.3
Collect sample in a 4 ounce jar.
This will provide a sufficient amount
of all quality control testing.
Cool and maintain sample temperature
at 0-4°C from the time of collection
until analysis.
No holding times have
established for this method.
been
10 Sample preparation
10.1 Composite small amounts of sample by
mixing small amounts of sample in a
clean beaker. The composited sample
should total about 1 g and should be
taken from three to five points
within the sample container. Mix the
sub sample well with a stainless
steel spatula or glass rod to insure
homogeneity.
10.2 Weigh out three 50 mg aliquots of the
conposited sample into 20 ml vials.
10.3 Add 5 ml of reagent water to each
vial.
10.A Place sonication horn inside the vial
and sonicate for 5 min.
10.5 Quantitatively transfer the contents
of each vial into a 250 mt erlenmeyer
flask with 95 mL of reagent water.
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11
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10.6 Add 100 uL of 1 H Na2S203 to convert
all active Cl to inorganic Cl.
10.7 Acidify the samples to a pH of < 2
with concentrated HN03, approximately
200 uL
10.8 Add 5 ml of the nitrate stock
solution
10.9 Add one level scoop of activated
carbon
10.10 Shake the suspension for at least one
hour in a mechanical shaker
10.11 Filter the suspension through a
polycarbonate membrane filter.
Filter by suction until the liquid
level reaches the top of the carbon.
10.12 Wash the inside surface of the filter
funnel with approximately 25 ml of
nitrate wash solution in several
portions. After the level of the
final wash reaches the top of the
charcoal, filter by suction until the
cake is barely dry. The time
required for drying jshould 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.
10.13 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.
10.14 Using a squeeze bottle or micro
syringe, rapidly rinse the carbon
from the inside of the filter holder
onto the filter cake using smalt
portions of wash solution. Allow the
cake to dry under vacuun for no more
than 10 seconds after the final
rinse. Immediately turn the vacuum
off.
10.15 Using the tweezers, carefully fold
the polycarbonate filter in half,
then in fourths, making sure that no
.carbon is lost.
10.17 Halide determination by combustion
10.17.1 Place the- folded polycarbonate filter
containing the sample and GAC in a
quartz combustion boat, close the
airlock, and proceed with the
automated sequence.
10.17.2 Repeat automated sequence with second
and third sample aliquot.
10.17.3 Record the emulative signal from the
microcoulometer and determine the
concentration calibration data per
Section 12.
11 System and Laboratory Performance
11.1 At the beginning and end of each
eight hour shift during which
analyses are performed, system
performance and calibration are
verified. System performance and
calibration may be performed more
frequently, if desired.
11.1.1 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.
11.1.2 If performance and calibration are
not verified at the beginning and end
of the shift (or more frequently),
samples analyzed during" that period
must be reanalyzed.
•
11.1.3 If calibration is verified at the
beginning of the shift, recalibration
is not necessary; otherwise, the
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12
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instrument must be calibrated prior
to analyzing samples.
11.1.4 Cell maintenance and other changes to
the analytical system that can affect
system performance may not be
performed during the eight hour (or
shorter) period.
11.2 Calibration verification and ongoing
precision and recovery-calibration
and system performance are verified
by the analysis of the 10 ug PAR
standard.
11.2.1 Analyze the PAR standard (Section
6.7.1) and analyze a blank (Section
8.4) immediately thereafter at the
beginning and end of each shift.
Compute the concentration of organic
halide in the PAR standard and in the
blank. The blank shall be less than
2 ug Cl".
11.2.2 Subtract the result for the blank
from the result of the PAR standard,
and compute the percent recovery of
the blank-subtracted PAR standard.
The percent recovery shall be in the
range of 71 - 116 percent.
11.2.3 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 on-going
precision and recovery test (Section
11.2), or recalibrate (Section 7.5 -
7.6).
11.2.4 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 11.2), or recalibrate
(Section 7.5 - 7.6), and re-analyze
the sample set that was analyzed
during the eight hour shift.
11.2.5 If the recovery is within the
acceptable range at the end of the
shift, and samples are to be analyzed
during the next 8 hour shift, the end
of shift verification may be used as
the beginning of shift verification
for the subsequent shift provided the
next 8 hour shift begins as the first
shift ends.
11.3 Add results that pass the
specification in 11.2.2 to initial
and previous ongoing data. Update OC
charts to form a graphic
representation of continued
laboratory performance. Develop a
statement of laboratory data quality
for each analyte 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 = 95X
and sr = 5X, the accuracy is 85 -
105X.
12 Calculations
12.1 Calculate the concentration of
chloride (in micrograms) detected in
each sample and blank per the
following:
OX (Cl" corrected) (ug/g) = d(C - 8 )
/ M
where
C = Cl" from micro-coulometer, ug
8 = Cl" from micro-coulometer for the
blank (8.4), ug
H = mass of sample adsorbed, g
12.1.1 The replicate results must be
averaged and the resulting average
used as the sample result.
12.1.2 Calculate the relative
deviation (RSD).
standard
12.1.3 If the RSD is greater than 20
percent, the analyses must be
repeated.
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13
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12.1.4 If the RSO remains greater than 20
percent, the result may not be
reported for regulatory compliance
purposes.
12.2 High concentrations of OX--if the
amount of chloride exceeds the
calibration range, dilute the sample
by a factor of 10 and reanalyze.
12.3 Low concentrations of OX--the final
result should be significantly above
the level of a blank.
12.3.1 If the instrument response of a
sample exceeds the instrument
response of the blank by a factor of
at least 3, the result is acceptable.
12.3.2 If the instrument response of a
sample is less than three times the
instrument response of the blank, and
the sample has been diluted, analyze
a less dilute aliquot of sample.
12.3.3 If the instrument response of an
undiluted sample is less than three
times the instrument response of 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.
12.4 Report final results that meet all of
the specifications in this method as
the blank-subtracted value, in ug/L
Cl" (not as 2,4,6-trichlorophenol),
to three significant figures.
13 Method performance--the
specifications contained in this
method are based on single laboratory
data (reference 13). These
specification will be updated as
further data become available.
References
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).
2. Method 9020, USEPA Office of Solid
Waste, "Test Methods for Evaluating
Solid Waste, SW-846", Third Edition,
1987,
3. "Determination of adsorbable organic
halogens (AOX)", "German Standard
Methods for the analysis of water,
waste water and sludge -- General
parameters of effects and
substances1.1, Deutsche Industrie Norm
(DIN) Method 38 409, Part 14, DIN
German Standards Institute, Beuth
Verlag, Berlin, Germany (1987).
4. "Water quality - Determination of
adsorbable organic halogens (AOX)",
International Organization for
Standard/Draft International
Standardization (ISO/DIS) Method 9562
(1988).
5. "Organically bound chlorine by the
AOX method", SCAN-U 9:89,
Secretariat, Scandinavian Pulp, Paper
and Board Testing Committee, Box
5604, S-11486, Stockholm, Sweden
(1989).
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).
7. "Canadian Standard Method for the
Determination of Adsorbable Organic
Hal ides (AOX) in Waters and
Wastewaters", Environment Canada and
The Canadian Pulp and Paper
Association (1990).
8. 40 CFR Part 136, Appendix B (49 FR
43234; October 26, 1984)t
9. "Working with Carcinogens," OHEU,
PHS, CDC, NIOSH, Publication 77-206,
(Aug 1977).
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14
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10. "OSHA Safety and Health Standards,
General Industry" OSHA 2206. 29 CFR
1910 (Jan 1976).
11. "Safety In Academic Chemistry
Laboratories," ACS Committee on
Chemical Safety (1979).
12. "Methods 330.4 and 330.5 for Total
Residual Chlorine," USEPA, EMSL
Cincinnati, OH 45268, EPA-4-79-020
(March 1979). '
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, Viar & Co, 300 N Lee St,
Alexandria VA 22314 (703-557-5040).
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