THE ANALYSIS OF TRlHALOM£THAf£S
IN DRINKING WATER BY LIQUID/LIQUID EXTRACTION
METHOD 501.2
November 1979
Physical and Chemical Methods Branch
Environmental Monitoring and Support Laboratory
Office of Research and Development
U.S-. Environmental Protection Agency
Cincinnati, Ohio 45268
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FOREWORD
This method has been prepared by the staff of the Environmental
Monitoring and Support Laboratory - Cincinnati, at the request of the Office
of Drinking Water, with cooperation from the Technical Support Division, OOW
and the Municipal Environmental Research Laboratory. Their comments and
suggestions on updating the SeptemDer 9, 1977, Interim Method as well as
those of the Health Effects Research Laboratory are gratefully acknowledged.
The procedure represents the current state-of-the-art, but as time
progresses, improvements are anticipated. Users are encouraged to identify
problems and assist in updating the method by contacting the Environmental
Protection Agency, Environmental Monitoring and Support Laboratory,
Cincinnati, Ohio 45268.
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Analysis of Trihalomethanes in Drinking
Water by Liquid/Liquid Extraction
1. Scope
1.1 This method (1,2) is applicable only to the determination of four
trihalomethanes, i.e., chloroform, brcmodichloromethane,
chlorodibrcmomethane, and bromoform in finished drinking water,
drinking water during intermediate stages of treatment, and the raw
source water.
1.2 For compounds other than the above-mentioned trihalomethanes, or
for other sample sources, the analyst must demonstrate the useful-
ness of the method by collecting precision and accuracy data on
actual samples as described in (3) and provide qualitative
confirmation of results by_Gas Chromatography/Mass Spectrometry
(GC/MS) (4).
1.3 Qualitative analyses using GC/MS or the purge and trap metnod (5)
must be performed to characterize each raw source water if peaxs
appear as interferences in the raw source analysis.
1.4 The method has been shown to be useful for the trihalometnanes over
a concentration range from approximately 0.5 to 200 ug/L. Actual
detection limits are highly dependent upon the characteristics of
the gas chromatographic system used.
2. Summary
2.1 Ten milliliters of sample are extracted one time with 2 ml of
solvent. Three. vl of the extract are then injected into a gas
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chromato graph equipped with a linearized electron capture detector
for separation and analysis.
2.2 The extraction and analysis time is 10 to 50 minutes per sample
depending upon the analytical conditions cnosen. (See Taole 1 ana
Figures 1, 2, and 3.)
2.3 Confirmatory evidence is obtained using dissimilar columns and'
temperature programming. Wh/»n component concentrations are
sufficiently high (>50 ug/l), halogen specific detectors may be
employed for improved specificity.
2.4 Unequivocal confirmatory analyses at high levels (>50 ug/L) can oe
performed using GC/MS in place of the electron capture detector.
At levels below 50 ug/L, unequivocal confirmation can only be per-
formed by the purge and trap technique using GC/MS (4, 5).
2.5 Standards dosed into organic free water and the samples are
extracted and analyzed in an identical manner in order to comperi-
sate for possible extraction losses.
2.6 The concentration of each trihalomethane is summed and reported as
total trihalomethanes in ug/L.
3. Interferences
3.1 Impurities contained in the extracting solvent usually account for
the majority of the analytical proolems. Solvent blanks should De
analyzed before a new bottle of solvent is used to extract samples.
Indirect daily checks on the extracting solvent are obtained by
monitoring the sample blanks (6.4.10). Whenever an interference is
noted in the sample blank, the analyst should reanalyze the
extracting solvent. The extraction solvent should be discarded
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whenever a high level (>10 ug/L) of interfering compounds are
traced to it. Low level interferences generally can de removed DV
distillation or column chromatography (6); however, it is generally
more economical to obtain a new source of solvent or select one of
the approved alternative solvents listed in Section 5.1.
Interference free solvent is defined as a solvent containing less
than 0.4 ug/L individual trihalomethane interference. Protect
interference-free solvents by storing in a non-laboratory area
known to be free of organochlorine solvents. Subtracting blank
values is not recommended.
3.2 Several instances of accidental sample contamination have oeen
attributed to diffusion of volatile organics through the septum
seal on the sample bottle during shipment and storage. The sample
blank (6.4.10) is used to monitor for this problem.
3.3 This liquid/liquid extraction technique efficiently extracts a wide'
boiling range of non-polar organic compounds and, in addition,
extracts the polar organic components of the sample witn varying
efficiencies. In order to perform the trihalomethane analysis as
rapidly as possible with sensitivities in the low ug/L range, it is
necessary to use the semi-specific electron capture detector and
chromatographic columns which have relatively poor resolving power.
Because of these concessions, the probability of experiencing
chromatograpnic interferences is high. Trihalomethanes are
primarily products of the chlorination process and generally do not
appear in the raw source water. The absence of peaks in the raw
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source water analysis with retention times similar to the trinalc-
methanes is generally adequate evidence of an interference-free
finished drinking water analysis. Because of these possible inter-
ferences, in addition to each finished drinking water analysis, a
representative raw source water (6.4.5) must be analyzed. When
potential interferences are noted in the raw source water analysis,
the alternate chromatographic columns must be used to reanalyze the
sample set. If interferences are still noted, qualitative
identifications should be performed according to Sections 2.3 and
2.4. If the peaks are confirmed to be other than trihalomethanes
and add significantly to the total trihalomethane value in the
finished drinking water analysis, then the sample set must be
analyzed by the purge and trap method (5).
4. Apparatus • • •
4.1 Extraction vessel"- A 15 mL total volume glass vessel with a Teflon
lined screw-cap is required to efficiently extract the samples.
4.1.1 For samples that do not form emulsions 10"mL~sc~r'ew-cap"
flasks with a Teflon faced septum (total volume is ml.) are
recommended.
Flasks and caps - Pierce - #13310 or equivalent
Septa - Teflon silicone - Pierce #12718 or equivalent.
4.1.2 For samples that form emulsions (turbid source water) 15 mL
screw cap centrifuge tubes with a Teflon cap liner are
recommended.
Centrifuge tube - Corning 8062-15 or equivalent.
4.2 Sampling containers - 40 ml screw cap sealed with Teflon faced
silicone septa.
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Vials and caps - Pierce #13075 .or. equivalent.
Septa - Pierce #12722 or equivalent.
4.3 Micro syringes - 10, 100 UL.
4.4 Micro syringe - 25 uL with a 2-inch oy 0.006-inch needle - ,amil:cn
702N or equivalent.
4.5 Syringes - 10 ml glass hypodermic with Luerlok tip (2 each).
4.6 Syringe valve - 2-way with luer ends (2 each) - Hamilton
#86570-1FM1 or equivalent.
4.7 Pipette - 2.0 ml. transfer.
4.3 Glass stoppered volumetric flasks - 10 and 100 ml.
4.9 Gas chromatograph with linearized electron capture detector.
(Recommended option - temperature programmaDle. See Section 4.12).
4.10 Column A -.4 mm ID x 2m long glass packed with.3% SP-1000 on
Supelcoport (100/120 mesh) operated at 50°C with 60 mL/min flow.
(See Figure 1 for a sample chrcmatogram and Table 1 for retention
data).
4.11 Column Bf- 2 m ID x 2m long glass packed with 10% squalane on
Chromosorto WAW (30/100 mesh) operated at 67°C with 25 mt/min
flow. This column is recommended as the primary analytical
column. Trichloroethylene, a common raw source water contaminate,
coelutes with bromodichloromethane. (See Figure 2 for a sample
chromatogram and Table 1 for retention data.)
4.12 Column C - 2 mm ID x 3m long glass packed with 6i OY-11/4% SP-2100
on Supelcoport (100/120 mesh) temperature program 45°C for 12
minutes, then program at l°/minute to 70°C with a 25 mL/min
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(See Figure 3 for a sample chromatogram and Taole I for
retention data.)
4.13 Standard storage containers - 15 ml amber screw-cap septjm oof.'.es
with Teflon faced silicone septa.
Bottles and caps - Pierce *19830 or equivalent.
Septa - Pierce #12716 or equivalent.
5. Reagents
5.1 Extraction solvent - (See 3.1).
Recommended - Pentane3
Alternative - hexane, methyl eyelohexane or 2,2,4-trimethylpentane.
aPentane has been selected as the best solvent for this analysis
because it elutes, on all of the columns, well before any of the
trihalomethanes. Hi^h altitudes or laboratory temperatures in
excess of 75°F may make the use of this solvent impractical. For
these reasons, alternative solvents are acceptable; however, the
analyst may experience baseline variances in the elution areas of
the trihalomethanes due to coelution of these solvents. The degree
of difficulty appears to be dependent upon the design and condition
of the electron capture detector. Such problems should be
insignificant when concentrations of the coeluting trihalomethane
are in excess of 5 ug/l.
5.2 Methyl alcohol - ACS Reagent Grade
5.3 Free and combined chlorine reducing agents - Sodium thiosulfate ACS
Reagent Grade - sodium sulfite ACS Reagent Grade.
5.4 Activated carbon - Filtrasorb - 200, available from Calgon
Corporation, Pittsburgh, PA, or equivalent.
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5.5 Standards:13
5.5.1 Sromofonti 965 - available from Aldrich Chemical
5.5.2 Bromodichloromethane 975 - available from Aldricn Chemical
Company.
5.5.3 Chlorodibromomethane - available from Columbia Chemical,
Incorporated, Columbia, S.C.
5.5.4 Chloroform 99% - available from Aldrich Chemical Company.
5.6 Organic-free water - Organic-free water is defined as water free af
interference when employed in the procedure described herein.
5.6.1 Organic-free water is generated by passing tap water through
a carbon filter bed containing carbon. Change the activated
carbon whenever the concentration of any triha 1 onethane
exceeds 0.4 ug/L.
'5.6.2 A Mill.ipore Super-Q Water System or its equivalent may be
used to generate organic-free deionized water.
5.6.3 Organic-free water may also be prepared by boiling water for
15 minutes. Subsequently, wlvile maintaining the temperature
at 90 C, bubble a contaminant free inert gas througn the
water at 100 mL/minute for one hour. 'While still hot,
transfer the water to a narrow mouth screw cap bottle with a
Teflon seal.
5.6.4 Test organic free water each day it is used by analyzing it
according to Section 7.
a precautionary measure, all standards must be checked for purity by
boiling point determinations or GC/MS assays.
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5.7 Standard stock solutions
5.7.1 Fill a 10.0 ml ground glass stoppered volumetric flask witn
approximately 9.8 ml of methyl alcohol.
5.7.2 Allow the flask to stand unstoppered about 10 minutes or
until all alcohol wetted surfaces dry.
5.7.3 Weigh the unstoppered flask to the nearest 0.1 mg.
5.7.4 Using a 100 UL syringe, immediately add 2 to 3 drops of the
reference standard to the flask, then reweigh. 3e sure that
the reference standard falls directly into the alcohol with-
out contacting the neck of the flask.
5.7.5 Dilute to volume, stopper, then mix by inverting the flask
several times.
5.7.6 Transfer the standard solution to a dated and labeled 15 ml
screw-cap bottle witn a TefVon cap liner. '
NOTE: Because of tne toxicity of trihalomethanes, it is
necessary to prepare primary dilutions in a hood.
It is.furtfl^r recomnenoed.that.a NIOSH/MESA-approved
toxic gas rtsoir»tor be used when the analyst
handles Mgn concentrations of such materials.
5.7.7 Calculate the concentration in micrograms per microliter
from the net gain m ««ignt.
5.7.8 Store the solution *t 43:.
NOTE: All standard solutions prepared in methyl alcohol
are stable u0 to 4 «««ks when stored under these
conditions. They snould be discarded after that
•time has elapsed.
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5.3 Aqueous calibration standard precautions
5.3.1 In order to prepare accurate aqueous standard solutions, the
following precautions .rust be observed:
a. Do not inject more than 20 UL of alcoholic standards into
100 mL of organ.ic-free water.
b. Use a 25 UL Hamilton 702N microsyringe or equivalent.
(Variations in needle geometry will adversely affect tne
ability to deliver reproducible volumes of methanolic
standards into water.)
c. Rapidly inject tne alcoholic standard into the'expanded
area of the filled volumetric flask. Remove the needle
as fast as possible after injection.
- d. Mix aqueous standards by inverting the flask three times
only.
e. Discard the contents contained in the neck of the flask.
Fill the sample synng« from the standard solution con-
tained in tne e*o*ided area of the flask as directed in
Section 7.
f. Never use pip«ts to 11 lute or transfer samples and
aqueous standards.
g. Aqueous standards, «nen stored with a headspace, are not
stable and snould s« discarded after one hour. Aqueous
standards can bf starts according to Sections 6.4.9 and -
7.2.
.9.
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5.9 Calibration standards
5.9.1 Prepare, from the standard stock solutions, a multicomponent
secondary dilation mixture in methyl alcohol so that a 20 uL
injection into 100 ml of organic-free water will generate a
calibration standard which produces a response close (* 25%)
to that of the unknown. (See 8.1).
5.9.2 Alternative calibration procedure
5.9.2.1 Construct a calibration curve for each trihalo-
methane containing a minimum of 3 different concen-
trations. Two of the concentrations must bracket
each unknown.
5.9.3 Extract and analyze the aqueous calibration standards in the
same manner as the unknowns.
5.9.4 Other calibration procedures (7) which require the delivery
of less than 20 uL of methanolic standards to 10.0 ml
volumes of water contained in the sample syringe are
acceptable only if the methanolic standard is delivered by
the solvent flush technique (8).
5.10 Quality Check Standard Mixture
5.10.1 Prepare, from the standard stock solutions, a secondary
dilution mixture in methyl alcohol that contains 10.0 ng/ui.
of each compound. (See 5.7.6 and 5.7.3).
5.10.2 Daily, prepare and analyze a 2.0 ug/L aqueous dilution from
this mixture by dosing 20.0 uL into 100 ml of organic-free
water (See Section 8.1).
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• Sample Collection and Handling
6.1 The sample containers should have a total volume of at least 25 ,,L.
6.1.1 Narrow-nouth screw-cap bottles with tne TFE fluorocarbon
faced silicons septa cap liners are strongly
6.2 Glassware Preparation
6.2.1 Wash all sample bottles, TFE seals, and extraction flasks in
detergent. Rinse with tap water and finally with distilled
water.
6.2.2 Allow the bottles and seals to air dry, then place in an
I05°C oven for 1 hour, then allow to cool in an area known
to be free of organics.
NOTE: Oo not heat the TFE seals for'extended periods of
time (>l hou» because the siHcone layer slowly'
degrades at 105°C.
6.2.3 'When cool, seal the bottles using the TFE seals that *ill oe
used for seaVlhg'the ""sample's". " "'"" '''
6.3 Sample stabilization - A chemical reducing agent (Section 5.3) is
added to all samples in order to arrest the formation of additional
trihalcmethanes after sample collection (7,9) and to eliminate t.ie
possibility of free chlorine reacting with impurities in tne
extraction solvent to form interfering organohalides. DO NOT ADD
THE REDUCING AGENT TQ SAMPLES AT COLLECTION TIME WHEN DATA FM
MAXIMIM TRIHALOHETHAME FORMATION IS DESIRED. If chemical
stabilization is employed, then the reagent is also added to the
blanks. The chemical agent (2.5 to 3 mg/40 ml) is added in
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crystalline form to the empty sample Dottle just prior to snipping
to the sampling site. If chemical-stabilizator! is not employed at
sampling time then the reducing .agent is added just before
extraction..
6.4 Sample Collection
6.4.1 Collect all samples in duplicate.
6.4.2 Fill the sample bottles in such a manner that no air bubbles
pass through the sample as the bottle is filled.
6.4.3 Seal the bottle so that no air bubbles are entrapped in it.
6.4.4 Maintain the hermetic seal on the sample bottle until
analysis.
6.4.5 The raw source water sample history should resemble the
finished drinking water. The average retention time of the
finished drinking water .within the water plant should be
taken into account when sampling the raw source water.
6.4.6 Sampling from a water tap.
6.4.6.1 Turn on the water and allow the system to flush
until the temperature of the water has staoilized.
Adjust the flow to about 500 mt/minute and collect
duplicate samples from the flowing stream.
6.4.7 Sampling from an open body of water.
6.4.7.1 Fill a 1-quart wide-flwuth bottle with sample from a
representative area. Carefully fill duplicate
sample bottles from the 1-quart bottle as in 6.4.
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,.4., ,f a ch^ical reducing agent has b^added^to the^e
._ ^_ ^ - -£-511 with s3inp16 3ust v-u
WM>^IAC_ Till fti**11 **~ r
ottles, f1ll
bottle, and shake vigorously for 1 .nnutt.
. 4 9 Sealing practice for sept™ seal sere- cap bottles.
r ,. Pen the -tie ana «„ - overflo-ing. PU- °" •
seal upon the convex sample -niscus and seal the
bottle by screvln, the cap on tightly.
649.2Invert the s^le and lightly tap the cap on a sol,*
" surf»ce. The absence of entrapped air indicates a
su«essfUl seal. If bubbles are present, open the
bottle, add a f. additional drops of sa-nple, then
reseal bottle as above.
a A in Samole blanks
" TlO, Pr.p« — 1. create at t,e labo.a^
by filling and sealing ,«p1. bottle with
organic-free water just prior to shipping the
sample bottles to the sampling site.
i- « to be stabilized, add an
6.4.10.2 If the sample is to be
identical amount of reducing agent to the
blanks.
..4.10.3 Ship the blanks to and f*. the sampling site
along with the sample bottles.
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6.4.10.4 Store the blanics and the samples, colle*
a given site (sample set), together in
protected area known to oe free from
contamination. A sample set is defined
the samples collected at a given site (
a water treatment plant, duplicate raw :
water, duplicate finished water and the
duplicate sample blanks comprise the sar
set).
6.5 When samples are collected and stored under these conditions
measurable loss of trihalomethanes has been detected over e;
periods of time (7). It is recommended that the samples be
analyzed within 14 days of collection.
7. Extraction and Analysis
7.1 Remove the plungers from two 10-mL syringes and attach a clc
syringe valve to each.
7.2 Open the sample bottle0 (or standard) and carefully pour the
-ample into one of the syringe barrels until it overflows. Re
the plunger and compress the sample. Open the syringe valve a
vent any residue air while adjusting the sample volume to 1C
Close the valve.
7.3 Fill the second syringe in an identical manner from the same
bottle. This syringe is reserved for a replicate analysis (
and 8.4).
clf for any reason the chemical reducing agent has not been added to
sample, then it must be added just prior to analyses at the rate of
3 mg/40 mL or by adding 1 mg directly to the sample in the extracior
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7.4 Pipette 2.0 ml of extraction solvent into a clean extraction flasx.
7.5 Carefully inject the contents of the syringe into the extraction
flask.
7.5 Seal with a Teflon faced septum.
7.7 Shake vigorously for 1 minute.
7.3 Let stand until the phases separate (- 60 seconds).
7.8.1 If the phases do not separate on standing then
centrifugation can be used to facilitate separation.
7.9 Analyze the sample by injecting 3.0 uL (solvent flush
technique, (8)) of the upper (organic) phase into the gas
chromatograph.
8. Analytical Quality Control
8.1 A 2 ug/L quality check standard. (See 5.10) should be extracted and
analyzed each day before any samples are analyzed'. Instrument-
status checks and lower limit of detection estimations based upon
response factor calculations at 5 times the noise level are
obtained from these data. In addition, the data obtained from the
quality check standard can be used to estimate the concentration of
the unknowns. From this information the appropriate standards can
be determined.
8.2 Analyze the sample blank and the raw source water to monitor for
potential interferences as described in Sections 3.1, 3.2, and 3.3.
8.3 Spiked samples
8.3.1 For those laboratories analyzing more than 10 samples a day,
each 10th sample analyzed should be a laboratory-generated
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spike which closely duplicates the average finished
water in trihalomethane composition and concentration.
Prepare the spiked sample in organic-free water as described
in 5.9.
3.3.2 En those laboratories analyzing less than 10 samples daily,
each time the analysis is performed, analyze at least one
laboratory generated spike sample which closely duplicates
the average finished drinking water in trihalomethane
composition and concentration. Prepare the spiked sample in
organic-free water as described in Section 5.9.
8.3.3 Maintain an up-to-date log on the accuracy and precision
data collected in Sections 8.3 and 8.4. If results are
significantly different than those cited in Section 10.1,
• - • the analyst should check out the entire analysis scheme to
determine why the laboratory's 'precision and accuracy "limits
are greater.
8.4 Randomly select and analyze 10* of all samples in duplicate.
8.5 Analyze all samples in duplicate wnich appear to deviate more than
30% from any established norm.
8.6 Quarterly, spike an EMSl-Cincinnati trihalomethane quality control
sample into organic-free water and analyze.
8.6.1 The results of the EMSL trihalomethane quality control
sample should agree within 20% of the true value for each
trihalomethane. If they do not, the analyst must check each
step io the standard generation procedure to solve the
problem.
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3.7 [t is important that the analyst be aware of the linear response
characteristics of the electron capture system that is utilized.
Calibration curves should be generated and rechecked quarterly for
each trihalomethane over the concentration range encountered in the
samples in order to confirm the linear response range of the system.
Quantitative data cannot be calculated from non-linear responses.
Whenever non-linear responses are noted, the analyst must dilute
the sample for re analysis..
8.8 Maintain a record of the retention times for each trihalomethane
using data gathered from spiked samples and standards.
8.8.1 Daily calculate the average retention time for each
trihalomethane and the variance encountered for the analyses.
/
8.8.2 If .individual trihalomethane retention time varies by'more
• than lOt over- an eight hour period or does not fall within
lOt of an established norm, the .system is "out of control."
The source of_jretentipn data variation must be corrected
before acceptable data can be generated.
9. Calculations
9.1 Locate each trihalomethane in the sample chromatogram by comparing
the retention time of the suspect peak to the data gathered in
8.8.1. The retention time of the suspect peak must fall'within the
limits established in 8.8.1 for a single column identification.
9.2 Calculate the concentration of each trihalomethane by comparing the
peak heights or peak areas of the samples to those of the
standards. Round off the data to the nearest ug/L or two
significant Figures.
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Concentration, U9/U
9.3 Calculate the total tri ha lome thane concentration (TTHM) by summing
the 4 individual trihalomethane concentrations in ug/L:
TTHM (ug/L) « (cone. CHC^Hconc. CHBrClj) ""(cone. CH8r2Cl Hconc.CHS^)
9.4 Calculate the limit of detection (LOO) for each trihalomethane not
detected using the following criteria:
LOO (ug/L) - (3TT x -(2 ug/L)
where:
8 » peak height (mm) of 2 ug/L quality check standard
A » 5 times the noise level in mm at the e^act retention time
of the trihalomethane or- the base line displacement in mm from
theoretical zero at tn« exact retention time for the trihalo-
methane. - :--...._.... -... : ____ _ - -: ....... ._..__- - ------
ATT « attenuation factor.
9.5 Report the results obtained fry* the lower limit of detection
estimates along with th« d«ti *zr the samples.
10. Precision and Accuracy
10.1 Single lab precision and accuricy. The data in Table II were
generated by spiking organ ic-frtt water with trihalomethanes as
described in 5.9. The mixtures ««r« analyzed by the analyst as
true unknowns.
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REFERENCES
1. Mieure, J. P., "A Rapid and Sensitive Method for Determining Volatile
Organohalides in Water," Journal AWMA. 69_, 60, 1977.
2. Reding, R., et al. "THM's in Drinking Water: Analysis by LIE and
Comparison to Purge and Trap", Organics Analysis in Water and
Wastewater, STP 686 ASTM, 1979.
3. "Handbook for Analytical Quality Control in Water and Wastewater
Laboratories," Analytical Quality Control Laboratory, National Environ-
mental Research Center, Cincinnati, Ohio, June 1972.
4. Budde, W.L., J.W. Eichelberger, "Organic Analysis Using Gas
Chroma to graphy-Mass Spectrometry," Ann Arbor Science, Ann Arbor,
Michigan, 1979.
5.
"The Analysis of Trihalomethanes in Finished Water by the Purge and Trap
Method," Environmental Monitoring and Support Laboratory, Environmental
Research Center, Cincinnati, Ohio, 45268, May 15, 1979.
6. Richard, J.J.; G.A. Junk, "Liquid Extraction for Rapid Determination of
Halomethanes in Water," Journal AWWA. 69_, 62, January 1977.
7. Brass, H.J., et al., "National Organic Monitoring Survey: Sampling and
Purgeable Organic Compounds, Drinking water Quality Through Source •
Protection," R. B. Pojasek, Editor, Ann Arbor Science,"?. 398, 1977.
8. White, L.D., et al . "Convenient Optimized Method for the Analysis of
Selected Solvent Vapors in Industrial Atmosphere," AIHA Journal, Vol.
31, p. 225, 1970.
9. Kopfler, F.C., et al . "GC/MS 3*t«mnnation of Volatiles for the National
Organics Reconnaissance Survey ;iORS} or Drinking Water, Identification
and Analysis of Organic Pollutirts m *ater,* L. H. Keith, Editor, Ann
Arbor Science, p. 87, 1976.
1071B
298
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Trihalomethane
TABLE I
Retention Times for Trihalomethanes
Retention Time, Minutes
Column A
Chloroform 1.0
Sromodichloromethane 1.5
Chlorodibromomethane 2.6
(di bromoch loromethane)
Bromoform 5.5
Column 8
1.3
2.5d
5.6
10.9
Column C
4.9
11.0
23.1
39.4
dOn this column,-trichloroethylene, a common raw source water contaminate,
coelutes with bromodichloromethane.
Table II
Single Laboratory Accuracy and Precision
Compound
CHC13
CHC13
CHBrCl?
CHBrCb
CHBrpCl
CHSr^l
CHBr3
CH8r3
Dose Level
uq/L
9.1
69
1.2
12
2.7
17
2.9
14
Number of
Samples
5
3
5
2
5
3
5
3
Mean
ug/L
10
73
1.3
15
2.0
16
2.2
16
Precision
Relative
Standard
Deviation, 5
11
5.3
9.8
1.4
17
9.9
10
12
Accuracy
Percent
Recovery
110
106
108
125
74
94
76
114
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0 -l 2 -4
COLUMN PACX1NG: 37.SP-1CCO
CARRIES GAS; 57, CH* IN ARGCN
CARRIES PLOW: 6C3 ML/MIN.
COLUMN TEM?5RATUR£ 5Q'C
OETSaCR: SLKTRON CAPTURE
RETENTION TIMS IN MINUTSS
1 PINJKWPH
EXTRACT
-------
bU
Z
uu
to
.
COLUMN PACKING:
SQUALANE CARRIER
PLOW: 2Sml/min COLUMN
TEMPERATURE: 67
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256X
5 6 7
TIME (min)
3
10
FIGURE 2. EXTRACT OF STANDARD
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COLUMN PACKING: 67, OV. 11 + 47, SP-2ICO
g CARRIER FlOW: 25 m!/min
2 TSMP6RATURE PROGRAM: 45°C-12 M1NUTSS
0 . 1-VMINUTE TO 70
G
a
2 «
vu ° 2 u-
< 1 = is
= U • wu >
M
0
ce
IIOltOFOftM
— I.I.I TRICIIIOI
VI
1
I
1!
2 2 S
- ^
• uy
1§ §1
>- G ^ Q
uj *Z CS «
— * O *
* 1 i
i
I
JU 1
= 2
w o
1 *
g
I ' A
i i i i j
5 10 15 20 25 30 35 40 45
TIME (min)
FIGURE 3. EXTRACT OF STANDARD
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