United States __. „ _„ ,. „„ „„„
Environmental Protection EPA# 600/4-81-059
Agency
v>EPA Research and
Development
The Determination of Halogenated Chemicals
in Water
by the Purge and Trap Method
Method 502.1
Prepared for
Joseph A. Cotruvo
Director
Criteria and Standards Division
Office of Drinking Water
Prepared by
Thomas A. Beliar
James J. Lichtenberg
Physical and Chemical Methods Branch
Environmental Monitoring and Support Laboratory
Cincinnati, Ohio 45268
us,
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Determination of Halogenated Chemicals
in Water by the Purge and Trap Method'
Method 502.1
1.0 SCOPE AND APPLICATION
1.1 This method is applicable to the determination of carbon
tetrachloride, 1,2-dichloroethane, tetrachloroethylene, 1,1,1,-tri-
chloroethane, trichloroethylene and vinyl chloride contained in
finished drinking water, raw source water, and such water in any
state of treatment. These compounds and an additional 44 halo-
genated compounds which can be determined by this method are listed
in Table I.
1.2 Single laboratory accuracy and precision data show that this proce-
dure is useful for the detection and measurement of multicomponent
mixtures spiked.into carbon filtered finished water and raw source
water at concentrations between 0.20 and 0.40 ug/L with method
detection limits generally less than 0.01 ug/L.. The method as
described is capable of accurately measuring those compounds men-
tioned in Table I over a concentration range of 0.10 to 5.0 ug/L.
Additionally, it is possible to measure individual organohalides up
to 1500 ug/L. However the ability to measure complex mixtures
containing co-eluting or partially resolved
1 Organic Analyses Section, Environmental Monitoring and Support
Laboratory, Cincinnati, Ohio 45268, April 1981,
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organohaTides with concentration differences larger than a factor
of 10 is hampered. This problem commonly occurs when finished
drinking waters are analyzed because of the relatively high
trihalomethane content. When such samples are analyzed chloroform
will affect the method detection limit for 1,2-dichloroethane.
1.3 This method is recommended for use only by analysts experienced in
the measurement of purgeable organics at the low ug/L level or by
experienced technicians under the close supervision of a such
qualified analyst.
2. Summary
2.1 An extraction/concentration technique is incorporated within the
method which enhances the quantities of organohalides injected into
the gas chromatograph by a factor of 1000 over direct injection gas
chromatography.
2.2 Organohalides are extracted by an inert gas which is bubbled
through the aqueous sample. The organohalides, noted in Table I
along with other organic constituents which exhibit low water
solubility and boil less than 200°C, are efficiently transferred
from the aqueous phase to the gaseous phase. These compounds are
swept from the purging device and are trapped in a short column
containing a carefully selected sorbant combination. After a
predetermined period of time, the trapped components are thermally
desorbed and backflushed onto the head of a gas chromatographic
column and separated under programmed conditions.
2.3 Measurement is accomplished with a halogen specific detector which
eliminates interference problems commonly encountered with
universal or semispecific detectors. Under special conditions
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(4.2.2c), a mass spectrometer may be used in place of a halogen
specific detector for quantitative measurement.
2.4 Confirmatory analyses are performed using dissimilar columns. If
sufficient material is present, confirmatory analyses are performed
by gas chromatography-mass spectrometry (GC/MS).
2.5 Aqueous standards and unknowns are extracted and analyzed under
identical conditions to compensate for extraction losses (See Table
1 for the purging efficiency of individual compounds).
2.6 To minimize personal exposure to known human carcinogens, an alter-
native non-aqueous calibration procedure is provided for vinyl
chloride. The gas chromatograph is calibrated by injecting dilute
commercially available gaseous standards of vinyl chloride into the
purging device as aqueous standards of other compounds are purged.
2.7 The total analysis time is approximately 1 hour per sample.
3. Interferences
3.1 During the development and testing of this method, certain analyti-
cal parameters and equipment design were found to affect the valid-
ity of the analytical results. Proper use of the method requires
that such parameters or design be used as specified. These items
are identified in the text by the word "must." Anyone wishing to
deviate from the method on these operations must demonstrate that
such a deviation does not affect the validity of the data. Alter-
native test procedure approval must be obtained through the
Environmental Monitoring and Support Laboratory - Cincinnati
Equivalency Program. An experienced analyst may make modifications
to parameters or equipment not identified by the word "must" as
long as the data obtained are equivalent to or better than that
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obtained with the method as presented in Section 9. Formal approval
is not required, but documented comparable data must be on file as
part of the overall quality assurance program.
3.2 Impurities contained in the purge- gas and organic compounds out
gasing from the plumbing ahead of the trap usually account for the
majority of contamination problems. The presence of such inter-
ferences is easily monitored using the quality control program
described herein. Field reagent blanks (FRB) are normally run
between each set (6.4.9.5) of samples. When a positive organohalide
response is noted in the FRB, the analyst should analyze a
laboratory reagent blank (LRB) inorder to identify the source of
contamination. LRB are run by charging the purging device with
reagent water and analyzing it in the normal manner. Whenever
organohalides are noted in the LRB, the analyst should change the
purge gas source and regenerate the molecular sieve purge gas
filter. Subtracting blank values from sample results is not
recommended. The use of non-TFE plastic tubing, non-TFE thread
sealants, or flow controllers with rubber components in the purging
device should be avoided since such materials out-gas organic
compounds which will be concentrated in the trap during the purge
operation. Such out-gassing problems are common whenever new
equipment is put into service. With use, minor out-gassing
problems generally cure themselves.
3.3 Several instances of accidental sample contamination have been
noted and attributed to diffusion of volatile organics through the
septum seal and into the sample during shipment and storage. The
FRB is used as a monitor for this problem. If the FRB is contain-
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inated according to 9.11 the entire sample set must be discarded
and resampled.
3.4 For compounds that are not efficiently purged, such as tetrachloro-
ethylene, small variations in sample volume, purge time, purge flow
rate, purging device geometry, or purge temperature can affect the
analytical result. Therefore, with the exception of vinyl
chloride, samples and standards must be analyzed under identical
conditions.
3.5 In cases of compounds with low boiling points, such as vinyl
chloride, small variations in purging conditions and trap configur-
ation can cause trap saturation and sample venting. For this
reason, sample volume, purging conditions and trap parameters must
be duplicated within the constraints of this method. Variations
are permitted only through the EMSL-Cincinnati Equivalency Program.
3.6 Cross-contamination can occur whenever high level and low level
samples are sequentially analyzed. To reduce the likelihood of
this, the purging device and sample syringe must be rinsed at least
twice between samples with reagent water. Whenever an unusually
concentrated sample is encountered, it is necessary that it be fol-
lowed by FRB or LRB analysis to check for sample cross contamina-
tion. Note: Cross-contamination problems vary between instruments.
It is up to the analyst to determine when this practice is
required. For samples containing large amounts of water soluble
materials, suspended solids, high boiling compounds or high organo-
halide levels it may be necessary to wash out the purging device
with a soap solution, rinse with distilled water, and then dry in a
105°C oven between analyses.
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3.7 Qualitative misidentifications can occur in gas chromatographic
analysis. Whenever samples whose qualitative nature is unknown are
analyzed, the following precautionary measures should be
incorporated into the analysis.
3.7.1 Perform duplicate analyses using the two recommended columns
(4.2.1.1 and 4.2.1.2) which provide different retention order
and retention times for many organohalides.
3.7.2 Whenever possible use GC/MS techniques which provide
unequivocal qualitative identifications.
3.3 To analyze for methylene chloride at concentrations below 1 ug/L
the laboratory will need to take the following special precautions.
The analytical and sample storage area should be isolated from all
atmospheric sources of methylene chloride, otherwise random back-
ground levels will result. Methylene chloride will permeate
through Teflon tubing. For this reason, all GC carrier gas lines
and purge gas plumbing should be constructed from stainless steel
or copper tubing. Laboratory clothing exposed to methylene
chloride fumes during common liquid/liquid extraction procedures
can contribute to sample contamination during steps described in
Sections 5, 6, and 8.
4. Apparatus
4.1 The purge and trap equipment consists of three separate pieces of
apparatus: the purging device, the trap, and the desorber.
Construction details for a purging device and an easily automated
trap-desorber hybrid that was used to generate the single
laboratory accuracy and precision data listed in Section 11 is
shown in Figures 1 through 4 and described in 4.1.1 through 4.1.3.
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4.1.1 Purging Device -- Construction details are given in Figure 1
for an acceptable all glass 5 ml purging device. The glass
frit installed at the base of the sample chamber allows
finely divided gas bubbles to pass through the sample while
the sample is restrained above the frit. Gaseous volumes
above the sample are kept to a minimum to eliminate dead
volume effects, yet allowing sufficient space for most foams
to disperse. The inlet and exit ports are constructed from
heavy walled 1/4 inch glass tubing so that leak-free
removable connections can be made using "finger-tight"
compression fittings containing Teflon ferrules. The
removable foam trap is used to control samples that foam.
The purging device must meet the following specifications:
a. The purging device must be designed to accept 5 ml
samples with a water column at least 3 cm deep.
b. The gaseous head space between the water column and the
trap must have a total volume of less than 15 ml.
c. The purge gas must pass through the water column as
finely divided bubbles with a diameter of less than 3 mm
at the origin.
d. The purge gas must be introduced no more than 5 mm from
the base of the water column.
4.1.2 Trapping Device — The trap (Figure 2) is a short gas
chromatographic column which, at 22°C, retards the flow of
the compounds of interest while venting the purge gas. A
trap is constructed with a low thermal mass so that it can
be rapidly heated for efficient desorption, then rapidly
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cooled to room temperature for recycling. The 3% OV-1 area
of the trap is used primarily as a thermal spacer to ensure
that the Tenax is contained in a heated area of the trap.
In addition, it isolates the Tenax area of the trap from
high boiling aerosols which may adversely affect the
performance of the Tenax.
The Tenax portion of the trap, under the given operating
conditions, quantitatively retains those compounds listed in
Table 1 from dichloromethane through p-dichlorobenzene
(compounds boiling above 35°C). The silica gel quantita-
tively retains chloromethane, bromomethane, vinyl chloride
and chloroethane and the charcoal quantitatively retains
dichlorodifloromethane.
Pack the trap according to Figure 2. In order to function
properly the trap must be constructed so that it meets or
exceeds the sorbant dimentions shown in Figure 2.
Additional requirements and acceptable modifications are as
follows:
a. Place the glass wool plug in the inlet end of the trap,
follow with the OV-1, Tenax, silica gel, charcoal, and
finally, the second glass wool plug. Reversing the
packing order (placing the charcoal in the trap first)
will cause the silica gel and Tenax layers to become
contaminated with charcoal dust causing poor desorption
efficiencies.
b. The trap must be installed so that the effluent from the
purging device enters the Tenax end of the trap.
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c. If it is not necessary to analyze for dichlorodifloro-
methane, the trap packing can be modified by eliminating
the charcoal and adding additional Tenax and silica gel.
In this situation, the packing order and dimensions of
the sorbents in the trap are as follows: 5 mm glass
wool, 1 cm 3% OV-1, 15 cm Tenax, 8 cm silica gel and 5 mm
glass wool.
d. If only compounds boiling above 35°C are to be
analyzed, the silica gel and charcoal area of the trap
can be replaced with Tenax providing a Tenax column of 23
cm.
4.1.3 Desorber assembly — Details for the desorber are shown in
Figures 3 and 4. With the 6-port valve in the Purge-Sorb
position (See Figure 3), the effluent from the purging
device passes through the trap where the flow rate of the
organics is retarded. The GC carrier gas also passes
through the 6-port valve and is returned to the GC. With
the 6-port valve in the Purge-Sorb position, the operation
of the GC is in no way impaired; therefore, routine liquid
injection analyses can be performed using the gas chroma-
tograph in this mode. After the sample has been purged, the
6-port valve is turned to the desorb position (See Figure 4).
In this configuration, the trap is coupled in series with
the gas chromatographic column allowing the carrier gas to
backflush the trapped materials into the analytical column.
Just as the valve is actuated the power is turned on to the
resistance wire wrapped around the trap. The power is
supplied by an electronic temperature controller. A
temperature sensor is attached to the silica gel/charcoal
area of the trap and wrapped with a double layer of
resistance wire.
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The trap is rapidly heated to 180°C with minimal tempera-
ture overshoot and maintained at that temperature. Under
these conditions, the Tenax area of the trap, wrapped with a
single layer of resistance wire is maintained at
approximately 130°C. The trapped compounds are released
as a "slug" to the gas chromatograph by this heat and
backflush step. Normally, packed columns with theoretical
efficiencies near 500 plates/foot under programmed
temperature conditions can accept such desorb injections
without altering peak geometry. Substituting a
non-controlled power supply, such as a manually operated
variable transformer, will provide non-reproducible
retention times and poor quantitative data unless the
Injection Procedure (8.9.2) is used.
NOTE: It is acceptable to heat the Tenax area of the trap
to 180°C. However, this practice generally causes early
trap failure. Trap failure is characterized by a pressure
drop in excess of three pounds per square inch across the
trap during purging or by poor bromoform sensitivities.
4.1.4 Several Purge and Trap devices are now commercially avail-
able. It is recommended that the following be taken into
consideration if a unit is to be purchased:
a. Be sure that the unit is completely compatible with the
gas chromatograph to be used for the analysis.
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b. Select a 5 mL purging device that meets the requirements
shown in (4.1.1).
c. The sorbant and sorbant areas of the trap must meet or
exceed the specifications listed in (4.1.2).
d. With the exception of sample introduction, select a unit
that has as many automated purge trap functions as
possible.
4.2. Gas chromatograph — The gas chromatograph column oven must be
capable of operating at 40°C ± 1°C, as well as temperature
programming. The gas chromatograph must be equipped with automatic
flow controllers so that the column flow rate will remain constant
throughout the temperature program. It may be necessary to cool
the column oven down to less than 30°C. See (8.9.2) A
subambient column temperature controller may be required to achieve
this.
4.2.1 Gas chromatographic columns — The gas chromatographic
columns and conditions listed below are recommended for the
analysis of complex mixtures of organohalides contained in
water samples. If these columns or conditions do not
adequately resolve the organohalides, the analyst may vary
the liquid phase, loading level, solid support, mesh range
column length, column internal diameter, or operating
temperatures in order to provide the required resolution.
The analyst must have on file adequate precision and
accuracy data to demonstrate that the modified system
provides data equivalent to that shown in Section 11 under
single laboratory accuracy and precision. Capillary columns
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and their associated specialized injection techniques are
not currently acceptable.
4.2.1.1 Column I is a highly efficient column which provides
outstanding separations for a wide variety of
organic compounds. Because of its ability to
resolve complex mixtures of organochlorine
compounds, Column I should be used as the primary
analytical column (See Figure 5).
Column I parameters: — Dimensions: eight feet long
x 0.1 inch ID stainless steel or glass tubing.
Packing: 1% SP-1000 on Carbopack-8 (60/80) mesh.
Carrier Gas: helium at 40 mL/minute. Temperature
program sequence: 45°C isothermal for three
minutes, program at 8°C/minute to 220°C then
hold for 15 minutes or until all compounds have
eluted.
NOTE: It has been found that during handling,
packing, and programming, active sites are exposed
on the Carbopack-B packing. This results in tailing
peak geometry and poor resolution of many
constituents. To protect the analytical column,
pack the first 5 cm of the column with 3% SP-1000 on
Chromosorb-W 60/80 mesh followed by the Carbopack-B
packing. Condition the precolumn and the Carbopack
columns with carrier gas flow at 220°C overnight.
Pneumatic shocks and rough treatment of packed
columns will cause excessive fracturing of the
Carbopack. If pressure in excess of 60 psi is
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required to obtain 40 mL/minute carrier flow, the
column should be repacked.
4.2.1.2 Column II provides unique organohalide-separations
when compared to those obtained from Column I (see
Figure 6). However, since the resolution between
various compounds is generally not as good as those
with Column I, it is recommended that Column II be
used as a qualitative confirmatory column for
unknown samples when GC/MS confirmation is not
possible.
Column II parameters — Dimensions: six feet long x
0.1 inch ID stainless steel or glass. Packing:
n-octane on Porisil-C (100/120 mesh). Carrier Gas:
helium at 40 cc/minute. Temperature progranr
sequence: 50°C isothermal for three minutes,
program at 6°/minute to 170°C, then hold for
four minutes or until all compounds have eluted.
4.2.2 Detector — A halogen specific detector must be used in
order to eliminate misindentifications due to non organo-
haTides which are coextracted during the purge step.
a. A Hall model 700-A available from Tracor has been tested
and found to provide the sensitivity needed to produce
meaningful analyses down to 0.10 ug/L for most organo-
halides with a relative standard deviation of less than
10%.
Recommended operating conditions for Hall 700-A Detector:
Reactor tube: nickel 1/16 inch O.D.
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Reactor temperature: 810°C (Optimize the detector
reactor temperature by analyzing a standard mixture
containing 10 ng/uL of methylene chloride, chloroform,
bromoform and tetrachloroethylene over a temperature
range from 700°C through 1000°C. Select the tempera-
ture that provides maximum response to the compounds of
highest interest.)
Reactor base temperature: 250°C
Electrolyte: 100% n-propyl alcohol
Electrolyte flow rate: 0.8 ml/minute
Reaction gas: hydrogen at 40 mL/minute
Carrier gas: helium at 40 mL/minute
b. Other halogen specific detectors including other
electrolytic conductivity systems and microcoulometric
titration can be used. The stability and sensitivity of
these detectors normally limit the method to measurements
down to 1.0 ug/L with a relative standard deviation near
10%.
c. GC/MS techniques are acceptable options to halogen
specific detectors for quantitative measurements. The
analyst must have on file single laboratory accuracy and
precision data at 0.1 times the required maximum
contaminant level to show that the system is adequately
sensitive to be used for this application. Additionally,
recoveries should be within 20% of the true value with a
relative standard deviation of less than 15% for repli-
cate sample.
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d. Flame Ionization and electron capture detectors are not
acceptable. Approval for their use must be obtained
according to Section 3.1.
4.3 Sample containers — 40-ml screw cap vials sealed with Teflon faced
silicone septa.
4.4 Syringes — 5 ml hypodermic with luerlok tip (2 each).
4-.5 Micro syringes — 10, 100 uL.
4.6 Micro syringe — 25 uL with a 2" by 0.006 inch I.D. needle
(Hamilton #702N or equivalent).
4.7 Syringe valve — 2-way with Luer ends (three each).
4.8 Volumetric flasks — modified 500 and 1000-mL. See Figure 7.
(Special order from specialty glassware vendor.)
4.9 Syringes — 0.5, 1.0, 5-mL gas-tight with shut off valve.
5. Reagents and Materials
5.1 Reagent safety precautions
5.1.1 The toxicity or carcinogenicity of each reagent in this
method have not been precisely defined; however, each
chemical compound should be treated as a potential health
hazard. From this viewpoint, exposure to these chemicals
must be reduced to the lowest possible level by whatever
means available. The laboratory is responsible for
maintaining a current awareness file of OSHA regulations
regarding the safe handling of the chemicals specified in
this method. A reference file of material data handling
sheets should also be made available to all personnel
involved in the chemical analysis.
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5.1.2 Vinyl chloride has been classified as a known human or
mammalian carcinogen. See Reference 1 for special
precautions and permissible exposure limits for vinyl
chloride.
5.2 Trap Materials
5.2.1 Porous polymer packing — 60/80 mesh chromatographic grade
Tenax GC (2,6-diphenyl-p-phenylene oxide).
5.2.2 OV-1 (3X) on Chromosorb-W 60/80 mesh.
5.2.3 Silica gel — 35/60 mesh Oavison, grade-15 or equivalent.
5.2.4 Coconut charcoal — (26 mesh) Barnaby Chaney, CA-580-26 lot
# M-2649 or equivalent.
5.3 Column packing — SP-1000 (1%) on Carbopack-8 (60/80 mesh)
available from Supelco.
5.4 Column packing — n-Octane on Porasil-C (100/120 mesh) available
from Waters Associates.
5.5 Column packing — SP-1000 (3%) on Chromosorb-W (60/80 mesh)
available from Supelco.
5.6 Dechlorinating compound — crystalline sodium thiosulfate, A.C.S.
Reagent Grade or sodium sulfite, A.C.S. reagent grade.
5.7 Activated carbon (for preparation of reagent water) --
Filtrasorb-200 or Filtrasorb-400, available from Calgon Corp.,
Pittsburgh, PA, or equivalent.
5.8 Reagent water
5.8.1 Reagent water is defined as water free of interference for
the compounds to be determined when employed in the purge
and trap procedure described herein. (See 9.11) It is
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generated by passing distilled or tap water through a carbon
filter bed containing about one pound of activated carbon.
5.8.2 A Millipore Super-Q Water System or its equivalent may be
used to generate reagent water.
NOTE: 1,2-dichloroethane and methylene chloride are common
contaminants found in depleted Super-Q Water Systems.
5.8.3 Reagent water may also be prepared by boiling water for 15
minutes. Subsequently, while maintaining the temperature at
90°C, bubble a contaminant free inert gas through the
water for one hour. While still hot, transfer the water to
a narrow mouth screw cap bottle with a Teflon seal.
5.9 Standards
5.9.1 Obtain at least 97% pure reagent grade reference standards.
From commercial sources or, as they become available, from
the EMSL-CI Quality Assurance Branch Repository, Cincinnati,
Ohio 45268.
5.9.2 Vinyl chloride — 99.9% Pure vinyl chloride in cylinders is
available from Ideal Gas Products, Inc., Edison, New Jersey
and upon request from Matheson, East Rutherford, New Jersey.
(See Reference 1 for safety precautions.) Certified
mixtures of vinyl chloride in nitrogen at 1.0 and 10.0 ppm
are available from several sources.
5.10 Standard Stock Solutions (compounds boiling above room temperature)
5.10.1 Place about 9.8 ml methyl alcohol into a 10-mL ground glass
stoppered volumetric flask.
5.10.2 Allow the flask to stand unstoppered for about 10 minutes or
until all alcohol wetted surfaces have dried.
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5.10.3 Weigh the flask to the nearest 0.1 mg.
5.10.4 Using a 100-uL syringe, immediately add 2 drops of the
reference standard to the flask, then reweigh. Be sure that
the 2 drops fall directly into the alcohol without
contacting the neck of the flask.
5.10.5 Dilute to volume, stopper, then mix by inverting the flask
several times.
5.10.6 Calculate the concentration in micrograms per microliter
from the net gain in weight.
5.10.7 Transfer the standard solution to a 10-mL screw-cap bottle
with a Teflon cap liner.
5.10.8 Store the solution at 4°C.
NOTE: With the exception of 2-chloroethylvinyl ether,
standard solutions prepared in methyl alcohol are stable up
to four weeks when stored under these conditions. They
should be discarded after that time has elapsed. Standard
solutions containing 2-chloroethylvinyl ether are stable for
one week.
5.11 Standard Stock Solutions (Gaseous Compounds)
5.11.1 Place about 9.8 mL of methyl alcohol into a 10.0-mL ground
glass stoppered volumetric flask.
5.11.2 Allow the flask to stand unstoppered about 10 minutes or
until all alcohol wetted surfaces have dried.
5.11.3 Weigh to the nearest 0.1 mg.
5.11.4 Fill a 5-mL valved gas-tight syringe with the reference
standard to the 5.0 ml mark.
5.11.5 Lower the needle to 5 mm above the methyl alcohol menicus.
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5.11.6 Slowly inject the reference standard into the neck of flask
(the gas will rapidly dissolve into the methyl alcohol).
5.11.7 Immediately reweigh the flask to the nearest 0.1 mg.
5.11.8 Dilute to volume, stopper, then mix by inverting the flask
several times.
5.11.9 Transfer the standard solution to a 10-mL screw cap bottle
with a Teflon cap liner.
5.11.10 Store stock solutions at < 0° C.
5.11.11 Stock solutions prepared from gaseous compounds are not
stable for periods exceeding one week. They should be
discarded after that time.
5.11.13 Calculate the concentration in micrograms per micro!iter
from the net gain in weight.
5.12 Calibration Standards
5.12.1 In order to prepare accurate aqueous standard solutions, the
following precautions must be observed.
a. Do not inject more than 20 uL of alcoholic standards into
100 ml of reagent water.
b. Use a 25-uL Hamilton 702N microsyringe or equivalent.
(Variations in needle geometry will adversely effect the
ability to deliver reproducible volumes of methanolic
standards into water.)
c. Rapidly inject the alcoholic standard into the expanded
area of the filled volumetric flask. (Figure 7.) Remove
the needle as fast as possible after injection.
The validity of the entire standard preparation scheme is monitored on a
quarterly basis by analyzing Certified Reference Standards as they
become available (See 9.6).
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d. Mix aqueous standards by inverting the flask three times
only.
e. For standards prepared in 500 or 1000-mL flasks, discard
the contents contained in the neck of the flask. Fill
the sample syringe from the standard solution contained
in the expanded area of the flask as directed in
paragraph 8.5.
f. Never use pipets to dilute or transfer aqueous standards
and samples.
g. Aqueous standards are not stable and should be discarded
after one hour unless stored and sealed according to
6.4.8 and 6.4.9.6.
5.12.2 Prepare, from the standard stock solutions, secondary
dilution mixtures in methyl alcohol so that a 20 uL
injection into 100, 500, or 1000 ml of reagent water will
generate a calibration standard which produces a response
close (±20%) to that of the unknowns.
Note: Comrnercially available primary or secondary dilutions
of organohalides in methane! may be used only if they are
supplied with a certified analysis.
5.12.3 Purge and analyze the aqueous calibration standards in the
same manner as the unknowns.
5.13 Calibration using certified mixtures of vinyl chloride in nitrogen.
5.13.1 The gas chromatograph can be calibrated for vinyl chloride
by injecting a known volume of a certified mixture of vinyl
chloride in nitrogen into the purging device as other
aqueous standards are being purged.
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5.13.2 Fill the purging device with 5.0 ml reagent water or aqueous
calibration mixture.
5.13.3 Start to purge the aqueous mixture. Inject a known volume
(between 100 and 2000 uL) of the calibration gas with a gas
tight syringe directly into the purging device. Slowly
inject the gaseous sample through the septum seal at the top
of the purging device at ZOOOuL/minute. Do not inject the
standard through the aqueous sample inlet needle. Inject
the gaseous standard before five minutes of the eleven
minute purge time have elapsed.
5.13.4 Record the volume of gaseous standard (ml), the barometric
pressure (mm of mercury) and the temperature of the vinyl
chloride gas (degree C) at the time of standardization.
5.14 Laboratory Control Standard (LC) (0.40 ug/L)
5.14.1 From the standard stock solutions, prepare a secondary
dilution in methyl alcohol containing 10 ng/uL of each
compound normally monitored.
NOTE: It may be necessary to prepare two or more LC so that
all of the compounds in each mixture are adequately resolved
for quantitative measurement.
5.14.2 Inject 20.0 uL of this mixture daily into 500 mL of reagent
water and analyze according to the Procedure, Section 8.
5.15 Certified Reference Standard — Obtain Certified Reference Standard
mixtures from the Environmental Monitoring and Support Laboratory -
Cincinnati, Quality Assurance Branch as they become available.
Dilute in reagent water according to the instructions supplied with
the mixture.
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6. Sample Collection and Handling
6.1 The sample containers should have a total volume in excess of 20 ml.
6.1.1 Narrow mouth screw cap bottles with the TFE fluorocarbon
faced silicone septa cap liners are strongly recommended.
Crimp-seal serum vials with TFE fluorocarbon faced septa are
acceptable if the seal is properly made and maintained
during shipment and storage.
6.2 Sample Bottle Preparation
6.2.1 Wash all sample bottles and TFE seals in detergent solution.
Rinse with tap water and finally with distilled water.
6.2.2 Allow the bottles and seals to air dry at room temperature,
place them in a 105°C oven for one hour, and allow to cool
in an area known to be free of organics.
NOTE: Do not heat the TFE seals for extended periods of
time, that is, for more than one hour because at 105°C the
silicone layer slowly begins to shrink.
6.2.3 When cool, seal the bottles with the TFE seals that will be
used for sealing the samples.
6.3 Sample Preservation — Either sodium thiosulfate or sodium sulfite,
chemical dechlorinating agents, is added to samples containing free
chlorine in order to arrest the formation of trihalomethanes after
2
sample collection. If chemical preservation is employed, the
preservative is also added to the blanks. The crystalline chemical
preservative (2.5 to 3 mg/40 mL) is added to the empty sample
bottles just prior to shipping to the sampling site. See Table II
to determine the stability of various organohalides in the presence
of sodium thiosulfate or sodium sulfite.
-------
6.4 Sample Collection
6.4.1 Collect a minimum of two samples from each sample source,
field duplicate-! (FD-1) and field duplicate-2 (FD-2).
6.4.2 Fill the sample bottles in such a manner that no air bubbles
pass through the sample as the bottle is being filled.
6.4.3 Seal the bottles so that no air bubbles are entrapped inside
them.
6.4.4 Maintain the hermetic seal on the sample bottle until time
of analysis.
6.4.5 Sampling from a water tap.
6.4.5.1 Turn on water and allow the system to flush. When
the temperature of the water has stabilized, adjust
the flow to about 500 mL/minute and collect FD-1 and
FD-2 samples from the flowing stream.
6.4.6 Sampling from an open body of water.
6.4.6.1 Fill a 1 quart wide mouth bottle or 1 liter beaker
with sample from a representative area. Carefully
fill FD-1 and FD-2 from the sampling container as
noted in 6.4.1 through 6.4.4.
6.4.7 If preservative has been added to the sample bottles, then
fill with sample just to overflowing, seal the bottle, and
shake vigorously for one minute.
6.4.8 Sealing practice for septum seal screw cap bottles.
6.4.8.1 Open the bottle and fill to overflowing, place on a
level surface, position the TFE side of the septum
seal upon the convex sample meniscus and seal the
bottle by screwing the cap on tightly.
-------
6.4.8.2 Invert the sample and lightly tap the cap on a solid
surface. The absence of entrapped air indicates a
successful seal. If bubbles are present, open the
bottle, add a few additional drops of sample and
reseal bottle as above.
NOTE: If the septum seals are inverted, that is, if
the silicone side comes in contact with the sample
significant organohalide losses will occur in
shipment and storage.
6.4.9 Blanks
6.4.9.1 Field Reagent Blanks (FRB) must be prepared and
accompany the samples wherever the samples are
shipped or stored. If the samples are immediately
analyzed at the sampling site, FRB are not required.
6.4.9.2 Prepare FRB in duplicate at the laboratory by
filling and sealing a minimum of two sample bottles
with pre-tested reagent water just prior to shipping
the sample bottles to the sampling site.
6.4.9.3 If the sample is to be preserved, add an identical
amount of preservative to the FRB.
6.4.9.4 Ship the FRB to and from the sampling site along
with the sample bottles.
6.4.9.5 Store the FRB and the samples collected from a given
source, called a sample set, together. A sample set
is defined as all the samples collected from a given
source at a given time, for example, at a water
-------
treatment plant, the duplicate raw source waters,
the duplicate finished waters and the duplicate FRB
samples comprise the sample set.
6.4.9.6 Store the sample set at 4°C in an area known to be
free of organic vapors. The maximum recommended
holding times are: vinyl chloride - six days,
carbon tetrachloride - 27 days, 1,2-dichloroethane -
27 days, 1,1,1-trichloroethane - 21 days, 1,1,2-tri-
chloroethylene - 27 days and 1,1,2,2-tetra-
chloroethylene - 27 days. See Table II for maximum
storage time for other organohalides.
7. Conditioning Traps
7.1 Condition newly packed traps overnight at 180°C by backflushing
•
with an inert gas flow of at least 20 ml_/minute.
7.1.1 Vent the trap effluent to the room, not to the analytical
column.
7.2 Daily prior to use, condition traps 10 minutes while backflushing
at 180°C.
7.2.1 The trap may be vented to the analytical column; however,
after conditioning the column must be programmed prior to
analysis of samples.
8. Procedure
8.1 Adjust the purge gas (nitrogen or helium) flow rate to 40 mL/minute.
8.2 Attach the trap inlet to the purging device. Turn the valve to the
purge-sorb position (Figure 3).
8.3 Open the syringe valve located on the purging device sample
introduction needle.
-------
8.4 Remove the plungers from two 5-mL syringes and attach a closed
syringe valve to each.
8.5 Warm the sample to room temperature then open the FD-1 bottle {or
standard) and carefully pour the sample into one of the syringe
barrels until it overflows. Replace the syringe plunger and
compress the sample. Open the syringe valve and vent any residual
air while adjusting the sample volume to 5.0 ml. Close the valve.
8.6 Fill the second syringe in an identical manner from the FD-1 sample
bottle. This second syringe is reserved for a duplicate FD-1
analysis, if necessary.
8.7 Attach the syringe-valve assembly to the syringe valve on the
purging device.
8.8 Be sure that the trap is cooler than 25°C then open the syringe
valve and inject the sample into the purging chamber. Close both
valves. Purge the sample for 11.0 ± 0.1 minutes.
8.9 After the 11 minute purge time, attach the trap to the chroma-
tograph (turn the valve to the desorb position) and introduce the
trapped materials to the GC column by rapidly heating the trap to
180°C while backflushing the trap with an inert gas between 20
and 60 mL/minute for four minutes.
8.9.1 If the trap can be rapidly heated to 180°C and maintained
at this temperature, the GC analysis can begin as the sample
is desorbed, that is, while the column is at the initial
45°C operating temperature. The equipment describee! in
Figure 4 will perform accordingly.
8.9.2 With other types of equipment (see 4.1.4) where the trap is
not rapidly heated or is not heated in a reproducible
-------
manner, it is necessary to transfer the contents of the trap
into the analytical column at 30°C where it is once again
trapped. Once the transfer is complete, which takes four
minutes, the column is rapidly heated to the initial
operating temperature for analysis.
NOTE: In some cases, it may be necessary to cool the
analytical column to 0°C.
8.9.3 If injection procedure 8.9.1 is used and the early eluting
peaks in the resulting chromatogram have poor geometry or
variable retention times, then method 8.9.2 must be used.
8.10 While the extracted sample is being introduced into the gas
chromatograph, empty the purging device using the sample intro-
duction syringe, follow by two 5-mL flushes of reagent water.
After the purging device has been emptied, leave the syringe valve
open to allow the purge gas to vent through the sample introduction
needle.
8.11 After desorbing the sample for approximately four minutes,
recondition the trap by returning the valve to the sorb position.
Wait 15 seconds, then close the syringe valve on the purging
device, allowing the purge gas to pass through the trap. Maintain
the trap temperature at 180°C. After approximately seven
minutes, turn off the trap power and open the syringe valve.
NOTE: If the operations described in 8.11 are omitted, large
amounts of water will be injected into the column. For certain
detectors, this will cause numerous large narrow peaks or detector
response quenching to occur in the early elution area of the
chromatogram on subsequent analysis.
-------
8.12 Analyze each FD-1 and FRB from the sample set in an identical
manner (see 6.4.9.5) on the same day.
8.13 Prepare single point calibration standards from the standard stock
solutions in reagent water that are close (±20%) to the unknown in
composition and concentration (9.5). The concentrations should be
such that no more than 20 uL of the secondary dilution need be
added to 100 to 1000 ml reagent water to produce a standard at the
same level as the unknown.
8.14 As an alternative to Section 8.13, prepare a calibration curve for
each organohalide containing at least three points, two of which
must bracket the unknown. Check the validity of calibration curves
daily by analyzing the LC (9.5).
8.15 As a second alternative to Section 8.13, internal standard
calibration techniques may be used. The following organohalides
are recommended for this purpose: Bromochloromethane,
2-bromo-l-chloropropane or 1,4-dichlorobutane. The internal
standard is added to the sample just before purging. Check the
validity of the internal standard calibration factors daily by
analyzing the LC sample (9.5).
8.16 For gaseous vinyl chloride, prepare single point calibration
standards within 20X of the sample or a calibration curve according
to 8.14. Check the validity daily by analyzing a gaseous standard.
9. Quality Control
9.1 Each laboratory that uses this method is required to operate a
formal quality control program. The minimum requirements of this
program consist of an initial demonstration of laboratory
capability and the analysis of spiked samples as a continuing check
-------
on performance. The laboratory is required to maintain performance
records to define the quality of data that is generated. As Agency
sponsored interlaboratory data is gathered for each parameter,
ongoing performance checks must be compared with these performance
criteria to determine if the results of analyses are within
accuracy and precision limits expected of the method.
9.1.1 Before performing any analyses, the analyst must demonstrate
the ability to generate acceptable accuracy and precision
with this method. This ability is established as described
in Section 9.2.
9.1.2 In recognition of the rapid advances that are occurring in
chromatography, the analyst is permitted certain options to
improve the separations or lower the cost of measurements.
Each time such modifications are made to the method, the
analyst is required to repeat the procedure in Section 9.2.
9.1.3 The laboratory must spike and analyze a minimum of 10% of
all FD-2 samples to monitor continuing laboratory
performance. This procedure is described in Section 9.4.
9.2 To establish the ability to generate acceptable accuracy and
precision in the use of this method, the analyst must perform the
following operations.
9.2.1 For each parameter normally measured, spike reagent water
with a methanolic standard solution so that the resulting
aqueous mixture contains each compound near the maximum
contaminant level.
9.2.2 Analyze a minimum of four different spiked samples. A
representative natural water may be used in place of the
-------
reagent water, but one or more additional aliquots must be
analyzed to determine background levels, and the spike level
must exceed twice the background level for the test to be
valid. Analyze the aliquots according to Section 8.
9.2.3 Calculate the average percent recovery, (R), and the
relative standard deviation of the concentration found.
Natural water background corrections must be made before R
calculations are performed.
9.2.4 After the Agency collects interlaboratory values for R and
s, then the laboratory must meet method performance criteria
established from these data.
9.3 The analyst must calculate method performance criteria and define
the performance of the laboratory for each spike concentration and
parameter being measured.
9.3.1 Calculate upper and lower control limits for method
performance:
Upper Control Limit (UCL) = R + 3 s
Lower Control Limit (LCL) = R - 3 s
where R and s are calculated as in Section 9.2.3.
The UCL and LCL can be used to construct control charts
*
that are useful in observing trends in performance.
9.3.2 The laboratory must develop and maintain separate accuracy
statements of laboratory performance for water samples. An
accuracy statement of the method is defined as R ± s. The
accuracy statement should be developed by the analysis of
four aliquots of natural water as described in Section
-------
9.2.2, followed by the calculation of R and s. Alternately,
the analyst may use four natural water data points gathered
through the requirement for continuing quality control in
Section 9.4. The accuracy statments should be updated
regularly.
9.4 The laboratory is required to collect a portion of their samples in
duplicate to monitor spike recoveries. The frequency of spiked
sample analysis must be at least 10% of all samples or one sample
per month, whichever is greater. One aliquot of the sample must
be spiked and analyzed as described in Section 9.2. If the
recovery for a particular parameter does not fall within the
control limits for method performance, the results reported for the
parameter in all samples processed as part of the same set must be
qualified as described in Section 10.4. The laboratory should
monitoring the frequency of data so qualified to ensure that it
remains at or below 5%.
9.5 Analyze the 0.40 ug/L LC sample daily before any samples are
analyzed. Instrument status checks are obtained from these data.
In addition, response factor data obtained from the 0.40 ug/L LC
standard can be used to estimate the concentration of the unknowns.
From this information the appropriate single point standard
dilutions can be determined for 8.13.
9.5.1 Calculate the response factor for each compound contained in
the LC sample. Compare the values to the mean of previously
determined factors. If they are different by more than
±10%, then run a duplicate LC sample to insure that the
instrument is operating properly.
-------
NOTE: Generally, for electrolytic conductivity detectors,
the first analysis of the day produces low response factors.
9.5.2 If Calibration Procedure 8.14 or 8.15 is used, then calcu-
late the concentration of each component in the 1C sample.
Each value must be within ±10% of the true value. If they
are not, then analyze a duplicate LC sample. If the
value(s) is still off by more than ±10%, then prepare a new
calibration curve.
9.6 Analyze the Certified Reference Standard (5.15) on a quarterly
basis. Dilute with reagent water according to the instructions
supplied with the mixture. The resulting analysis must agree
within (± 10%) of the certified values. If they do not, then
evaluate each step of the calibration procedure to identify and
correct the source of error. Analyze the Certified Reference
Standard whenever there is a reason to suspect the validity of
laboratory generated standard dilutions.
9.7 Analyze the FRB or a LRB to monitor for potential interferences as
described in Sections 3.2, 3.3 and 3.6.
9.8 Perform the following instrument status checks daily, using the
data gathered from standards, duplicate analyses and the LC sample.
9.8.1 Peak Geometry Check
9.8.1.1 All of the peaks contained in the LC chromatogram
must appear to be sharp and symmetrical. Peak
tailing in excess of that shown in the method
chromatogram Figure 5 must be corrected. Tailing
problems are generally traceable to:
-------
a. Active sites on GC column - repack.
b. Reactor temperature too low - see 4.2.2 (Hall
detector).
c. Reactor base temperature too low - see 4.2.2
(Hall detector).
d. Contaminated reactor tube-recondition or replace
(Hall detector).
e. Contaminated reactor transfer line - wash with
concentrated HC1 then dry or replace (Hall
detector).
f. Detector electrolyte flow too low - see 4.2.2.
g. Spent ion exchange column - Replace (Hall
detector).
h. Reactive area or large dead volume between
column and detector. Shorten transfer lines.
Recondition or replace transfer lines and
reactor base.
9.8.1.2 If only the compounds eluting before chloroform give
random responses, unusually wide peak widths, are
poorly resolved, or are missing, the problem is_
usually traceable to the trap/desorber. See
Sections 8.9.3, 4.1.2.
9.8.1.3 If only brominated compounds show poor peak geometry
or do not properly respond at low concentrations,
repack the trap. Excessive Hall detector reactor
temperatures can also cause low bromoform response.
9.8.1.4 If negative peaks appear in the chromatogram,
replace the ion exchange column and replace
electrolyte (Hall detector).
9.8.2 Randomly select and analyze 10% of all FD-2 samples. Field
duplicate-! and FD-2 analyses should agree within 10%.
-------
Poor agreement is generally traceable to:
a. Pneumatic leaks, especially around the purging device or
the Hall detector reactor inlet and exit.
b. Electronic problems.
c. Inexperienced operator.
d. Sampling and storage problems.
9.10 Maintain a record of the retention times for each organohalide
using data gathered from LC samples and standards.
9.10.1 Calculate the average retention time daily for each
compound normally monitored and the variance
encountered for the analyses.
9.10.2 If individual retention times vary by more than 10%
over an eight hour period or does not fall within 1056
of an established norm, the system is "out of
control." The source of retention data variation must
be corrected before acceptable data can be generated.
9.11 The FRB and LRB analysis should represent less than a 0.01 ug/L
response or less than a 10% interference for those compounds that
are reported.
9.12 Any instrument not performing according to 9.5, 9.6 and 9.10
specifications should be considered "out of control." The
instrument must be "in control" before acceptable data can be
generated.
10. Calculations
10.1 Identify each organohalide in the sample chromatogram by comparing
the retention time of the suspect peak to the data gathered in
-------
9.10. The retention time of the suspect peak must fall within the
limits established in 9.10 for single column identification.
10.2 Quantify the unknowns by comparing the peak area or peak height of
the unknowns to the standard peak area or height. Round off the
data to the nearest .01 ug/L or two significant figures.
,. a peak height sample x (concn. std, ug/L)
ug/ peak height standard
10.3 Calibration using vinyl chloride in nitrogen standards.
ug/L - 7^ (C) (V) (152)
T + 273
where ug/L = aqueous equivalent concentration of standard
P = atmospheric pressure (mm)
C s concentration of gaseous standard in ppm (volume:volume).
V « volume of standard injected into purging device (mL)
T - temperature of gaseous standard (degrees C.)
10.4 For samples processed as part of a set when laboratory spiked
sample recovery falls outside of the control limits in Section 9.4,
label the affected paratmeter as suspect.
11. Accuracy and Precision and Method Detection Limits
11.1 Precision and Accuracy for the Purge and Trap Method Using the Hall
700-A Detector under the conditons described in Section 4.2.2.
11.1.1 Both Ohio River water (ORW) and carbon filtered tap (CFT)
water were spiked with known amounts of organohalides. The
spiked solutions were then sealed in septum-seal vials both
with and without sodium thiosulfate (thio) and sodium
sulfite (sulfite) then stored on the bench top for up to
-------
four weeks. Samples were randomly analyzed on four
occasions. When matrix effects were noted or suspected,
these data were not included in the following single
laboratory precision and accuracy statement. Table II shows
the accuracy and precision data obtained from this study.
11.2 Precision and Accuracy for Purge and Trap Method using Hall 700
Detector.
11.2.1 Organic-free water was spiked with mixtures of
organohalides. The spiked water was used to fill septum seal
vials which were stored under ambient conditions. The
spiked samples were randomly analyzed over two weeks. The
data listed in Table III lists the accuracy and precision
data obtained from this Study.
11.3 Method detection Limits (MDL) were determined using the Hall 700-A
detector. Carbon filtered tap water was spiked with a mixture of
organihalides. Seven sample bottles were filed from the mixture
then analyzed. Spike levels were adjusted to provide a response at
2 to 10 times the noise level at the 2X attenuation setting. The
resulting data appear in Table IV.
-------
TABLE I
OR6ANOHALIDES TESTED USING PURGE AND TRAP METHOD
Compound
chloromethane
bromomethane
dichlorodifloromethane
vinyl chloride
chloroethane
di chloromethane
fluorotri chloromethane
allylchloride
1,1-dichloroethylene
bromoch 1 oromet hane
1,1 -di chloroethane
trans-1 ,2-dichloro-ethylene
cis-1 ,2-dichloro-ethylene
chloroform
1,2-dichloroethane
di bromomethane
1,1,1 -tri chloroethane
carbon tetrachloride
dichloroacetonitrile
bromodi ch 1 oromethane
2,3-dichloropropene
1 ,2-dichloropropane
1,1-dichloropropene
trans-1, 3 dichloropropene
1,1,2-trichloroethylene
1 ,3-dichloropropane
chlorodibromomethane
1 , 1 ,2-tri chloroethane
cis-l,3-dichloropropene
1,2-dibromoethane
2-chloroethyl ethyl ether
2-chloroethyl vinyl ether
bromoform
1,1,1 ,2-tetrach 1 oroethane
1,2,3-trichloropropane
chlorocyclohexane
1,1, 2, 2-tetrachl oroethane
1 ,1 ,2,2-tetrachloroethylene
Retention Time
(SEC)
Column I Column II
90
130
157
160
200
315
431
475
476
509
558
605
605
641
684
698
756
781
884
819
891
895
904
913
948
973
989
991
992
1046
1056
1080
1154
1163
1279
1283
1297
1300
317
•423
A
317
521
607
A
A
463
760
754
563
726
725
921
895
786
664
A
877
A
997
A
997
787
A
997
1084
1078
1131
A
A
1150
1302
A
A
A
898
CAS Number0
74-87-39
74-83-9
75-71-8
75-01-4
75-00-3
75-09-2
75-69-4
107-05-1
75-35-4
74-97-5
75-34-3
156-60-5
156-59-2
67-66-3
107-06-2
74-95-3
71-55-6
56-23-57
3018-12-0
75-27-4
78-88-6
78-87-5
563-58-6
10061-02-6
79-01-6
142-28-9
124-48-1 •
79-00-5
10061-01-5
106-93-5
7081-78-9
110-75-8
75-25-2
630-20-6
96-18-4
542-18-7
79-34-5
127-18-4
Purging
Efficiency
Percent
91
85
B
101
90
76
96
B
97
88
89
94
92
88
95
98
B
94
87
10
92
" 91
92
B
90
89
B
87
88
85
64
54
19
71
89
B
B
58
88
-------
TABLE I (Continued)
Compound
pentachloroethane
1 -ch 1 orocyc 1 ohexene- 1
chl orobenzene
1-chlorohexane
bis-2-chloroethyl ether
1 ,2-dibromo-3-chloropropane
bromobenzene
o-chlorotoluene
bis-2-chloroisopropyl ether
m-di chl orobenzene
o-di chl orobenzene
p-di chl orobenzene
Retention Time
(SEC)
Column I Column II
1300
1345
1451
1499
1500
1560
1626
1927
1931
2042
2094
2127
A
1186
1130
1229
A
A
A
1320
A
1346
1411
1340
CAS Number^
76-01-7
930-66-5
108-90-7
544-10-5
111-44-4
96-12-8
108-86-1
95-49-8
108-60-1
541-73-1
95-50-1
106-46-7
Purging
Efficiency
Percent
B
B
83
8
B
9
B
B
B
68
B
. 70
A - Not Determined
B = Not Determined
C = Chemical Abstracts Service Registry Number
-------
TABLE II
Single Lab Accuracy and Precision for Purge and Trap Method
Hall 700A Electrolytic Conductivity Detector
Compound
Chloromethane
bromomethane
vinyl chloride
di chl or odifluorome thane
chloroethane
di chloromethane
fluorotrichloromethane
1 , 1-dichloroethylene
allylchloride
bromochloromethane
1,1-dichloroethane
c1s+trans-l,2-dichloro-
ethylene
cis-l,2-d1chloro-
ethylene
1,2-dichloroethane
di bromomethane
1 , 1 , 1-trichloroethane
carbon tetrachlorlde
bromodichloromethane
2,3-dichloropropene
1 ,2-dichloropropane
1,1-dichloropropene
trans-1 ,3-dichloropro-
pene
cis-l,3-dichloropro-
pene
1 ,1 ,2-trichloroethane
1,3-dichloropropane
Spike
Level
0.40
0.40
0.20
0.40
0.40
0.20
0.40
0.40
0.40
0.40
0.20
0.20
0.40
0.20
0.40
0.40
0.20
0.20
0.20
0.40
0.40
0.40
0.40
0.40
0.40
Preserved
Sample
Thlo. Mean % Number of
C.F.TD O.R.WE Sulflte Recovery^ Samples
G
G,C
F
G
G
F
G
G
G,C
G
F
F
G
F
G
G
F
F
F
G
G
G,C
G,C
G
G
G
G
G
G
G
G
G
G
G,C
G
G
G
G
G
G
G
G
G
6.C
G
G
G,C '
G,C
G
G
G,A,B
G
F
G
G
F
G
G,A
G,C
G
F
F
G
F
G
G
F
F
F
G
G,A
G,C
G,C
G
G
93
85
no
103
93
85
90
88
85
90
95
95
88
110
100
93
90
100
95
95
88
88
90
95
98
16
8
12
12
20
17
21
18
8
19
17
17
20
17
5
20
17
17
14
20
18
4
4
15
21
Std.
Devia-
tion
.034
.025
.029
.081
.071
.024
.037
.037
.046
.038
.012
.011
.028
.014
.032
.032
.014
.013
.012
.014
.037
.000
.050
.024
.026
Rel. Maximum
Std. Holding
Devi a- Time
tion (Days)
8.5
6.3
15
20
18
12
9.3
9.3
12
9.5
6.0
5.5
7.0
7.0
8.0
8.0
7.0
6.5
6.0
3.5
9.3
.000
12.5
6.0
6.5
21
2
6
27
21
27
27
27
2
21
27
27
21
27
21
21
27
27
6
21
27
1
1
27
27
-------
TABLE II (Continued)
Spike
Level
Compound
ch 1 or od 1 bromomethane
1 , 1 ,2-trichloroethylene
1,2-dibromoethane
2-chloroethylether ether
2-chloroethylvlnyl ether
bromoform
1,1,1,2-tetrachloro-
e thane
1,2,3-trichloropropane
chlorocyclohexane
1,1,2,2-tetrachloro-
ethane
1,1,2,2-tetrachloro-
ethylene
pentachloroethane
1-chlorocyclohexene-l
chlorobenzene
1-chlorohexane
bis-2-chloroethylether
bromobenzene
o-chlorotoluene
bls-2-chlorolsopropyl
ether
m-dichlorobenzene
o-dichlorobenzene
p-dichlorobenzene
A - Matrix effect noted due
B - Matrix effect noted due
C - Matrix effect noted due
D - C.F.T. - carbon filtered
E - O.R.W - Ohio River water
F - Not determined.
ug/
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
to
to
to
20
20
40
40
40
20
40
40
40
40
20
40
40
40
40
40
40
40
40
40
40
40
the
the
the
C.F.TD
F
F
6
G
G
F
G
G
G
G
F
G
G
G
G,C
G,C
G
G
G
G
G
G
presence
presence
Preserved
Sample
Thio.
O.R.WE Sulfite
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G,C
G,C
G
G
G
G
G
G
F
F
G,B
G,A
G
F
G
G
G
G,A
F
G
G
G
G,C
G,C
G
G
G
G
G
G
of sodium sulfite
Mean %
Std.
Number of Devia-
Recovery Samples
95
94
93
95
100
95
93
100
93
95
90
98
« 93
88
83
100
93
85
125
95
95
90
(use of
of sodiumthiosulfate (use
sample storage
(recommended
storage
17
17
18
18
21
17
20
20
21
18
17
21
21
18
4
16
20
20
21
21
21
20
reagent not
of reagent
time noted
tion
.014
.012
.050
.030
.031
.030
.032
.038
.033
.036
.019
.039
.051
.037
.022
.065
.047
.037
.11
.033
.053
.051
Rel. Maximum
Std. Holding
Devia- Time
tion (Daysl
7.
6.
12.
7.
7.
15.
8.
9.
8.
9.
9.
9.
12.
9.
5.
16.
12.
9.
28.
8.
13.
13.
0
0
5
5
8
0
0
5
3
0
5
8
8
3
5
3
3
27
27
21
27
27
27
21
21
27
21
27
27
27
21
1
9
21
21
27
27
27
21
recommended).
not recommended).
in maximum
tap water.
G - These data included in recovery
and standard
age
column)
•
deviation calculations.
-------
Table III
Single Laboratory Accuracy and Precision for Trihalomethanes
Hall 700 Electrolytic Conductivity Detector
Dose
(ug/L)
1.19
11.9
119
Dose
(ug/L)
1.60
16.0
160
Dose
(ug/L)
1.96
19.6
196
Dose
(ug/L)
2.31
23.1
231
Chloroform
Number Mean Standard
samples (ug/L) deviation
12 1.21 0.14
8 11.3 0.16
11 105 7.9
Bromodi ch1oromethane
Number
samples
12
8
n
Mean
(ug/L)
1.52
15.1
145
Standard
deviation
0.05
0.39
10.2
Chlorodlbromomethane
Number
samples
12
8
11
Mean
(ug/L)
1.91
19.1
185
Standard
deviation
0.09
0.70
10.6
Bromoform
Number
samples
12
8
11
Mean
(ug/L)
2.33
22.5
223
Standard
deviation
0.16
1.38
16.3
-------
TABLE IV
METHOD DETECTION LIMITS FOR SELECTED ORGANOHALIDES
Relative
Spike Average Standard
Level Recovery Deviation
Compound
Methyl chloride
Vinyl chloride
Methyl bromide
Ethyl chloride
1 , 1 -0 i ch 1 oroethy 1 ene
1,1-Oichloroethane
Methyl ene chloride*-
cis+trans-l,2-0ichloroethylene
Chloroform
1,2-Oichloroethane
1 , 1 , 1-Trichloroethane
Carbon tetrachloride
Bromodi ch 1 oromethane
Dichloroacetonitrile
1 , 1 , 2-Trichl oroethy 1 ene
Chlorodibromomethane
1 , 1 ,2-Trichloroethane
1 ,2-Oibromoethane
2-Chloroethyl vinyl ether
2 -Chi oroethy 1 ethyl ether
Bromoform
1,1,2,2-Tetrachloroethane
1 , 1 , 2, 2-Tetrachl oroethy 1 ene
Chlorobenzene
1 ,2-Oibromo-3-chloropropane
MDLA= Method Detection Limit at
MDL a t(n_i
, V" I »
where:
ug/L Percent Percent
0.02
0.025
0.01
0.024
0.0125
0.0125
0.0125
0.0125
0.0125
0.0125
0.0125
0.0125
0.05
0.0063
0.0245
0.020
0.067
0.0502
0.050
0.0515
0.0198
0.0128
0.025
0.058
60
96
60
104
93
103
94
102
100
77
94
94
88
99
94
85
102
106
82
100
84
89
93
84
99% confidence that the
.99) (S)
MDL = the method detection 1
t(n-l,.99)= tne students' t value
imit
appropriate
26
8.5
52
9.2
7.0
4.6
5.5
7.6
7.4
9.3
6.8
5.2
28
3.6
6.8
13
12
39
14
12
20
4.4
7.9
19
value
for a
A. -i -i_ _
MDLA
0.01
0.006
0.1
0.008
0.003
0.002
0.002
0.002
0.002
0.003
0.003
0.002
0.04
0.0007
0.005
0.007
0.03
0.07
0.02
0.02
0.01
0.001
0.001
0.03
is not zero.
MDLB
0.001
0.01
0.03
0.003
0.003
0.003
0.002
0.002
0.002
0.001
0.002
0.003
0.04
0.0006
0.008
0.002
0.04
0.02
0.01
0.05
0.004
0.001
0.005
0.05
99% confidence
. . • -1_1_ — T
a
degrees of freedom.
S = standard deviation of the replicate analyses
MDLB= Estimated Method Detection limit
MDL8 = 3N X RF
when:
N = average noise level at retention time of organohalide
RF = response factor of organohalide
c = Average background level for methylene chloride 0.1 ug/L
-------
References
1. OSHA Safety and Health Standards, (29CFR1910) Occupational Safety
and Health Administration, OSHA 2206, (Revised January 1976).
2. Identification and Analysis of Organic Pollutants in Water,
Keith, L. H., Ann Arbor Science, p. 87 (1976).
3. "Handbook for Analytical Quality Control in Wastewater and
Wastewater Laboratories," EPA-600/4-79-019 U.S. Environmental
Protection Agency, Environmental Monitoring and Support Laboratory
- Cincinnati, Ohio 45268, March 1979.
-------
OPTIONAL
FOAM TRAP
EXIT 1/4
IN. O.O.
•— 14MM. O.O.
INLET 1/4
IN. 0.0.
1 4 IN. O.O. EXIT
SAMPLE INLET
2-WAY SYRINGE VALVE
17CM. 20 GAUGE SYRINGE NEEDLE
6MM.O.D. RUBBER SEPTUM
^ 10MM, O.D.
INLET
1/4 IN. O.O.
1/16 IN. O.O.
STAINLESS STEEL
13X MOLECULAR
SIEVE PURGE
GAS RLTER
10MM. GLASS FRIT
MEDIUM POROSITY
PURGE GAS
FLOW CONTROL
FIGURE 1. PURGING DEVICE
-------
PACKING PROCEDURE
CONSTRUCTION
MUUIPURPOSE I«AP
GIASS WOOl I/MM
ACIIVATED CHARCOAL 7.7CM
GRADE IS
SIUCA GEl 7.7CM
IfNAX 7.7CM
351 0V I (CM
GIASS WOOl
SMM
\
////////
/////
7"/fOOI MSISIANCE
WIRE WRAPPED SOIID _,-—
(DOUBLE LAYER)
I5CM
7-/fOOI (IfSISIANCE
WIRE WRAPPED SOUD
COMPRESSION NIIINO NU!
AND fERRUUS
IHERMOCOUm/CONIKOUER
SENSOR
IUCIRONIC
lEMPERAIURf
CONIRO1
AND 'I
PYROME1ER
IUBING J5CM 0105 IN. ID
OIJ5 IN. O.O. SlAINtESS SIEEl
IRAP INlif
FIGURE 2 TRAP
-------
CARRIER GAS FLOW CONTROL
PRESSURE REGULATOR
LIQUID INJECTION PORTS
PURGE GAS
FLOW CONTROL \
13X MOLECULAR
SIEVE FILTER
/ /
/
//;
/
'/
COLUMN OVEN
CONFIRMATORY COLUMN
TO DETECTOR
ANALYTICAL COLUMN
OPTIONAL 4-PORT COLUMN
SELECTION VALVE
TRAP INLET (TENTAX END)
6-PORT VALVE / RESISTANCE WIRE
HEATER CONTROL
NOTE: ALL LINES BETWEEN
TRAP AND GC
SHOULD BE HEATED
PURCINQ DEVICE TO 80°C
FIGURE 3 PURGE-TRAP SYSTEM (PURGE-SORB MODE)
-------
CARRIER GAS FLOW CONTROL
PRESSURE REGULATOR
PURGE GAS v
FLOW CONTROL X
13X MOLECULAR
SIEVE FILTER
LIQUID INJECTION PORTS
wwu4
OPTIONAL 4-PORT COLUMN
SELECTION VALVE
J
COLUMN OVEN
f
CONFIRMATORY COLUMN
TO DETECTOR
"^-^ ANALYTICAL COLUMN
TRAP INLET (TENAX END)
6-PORT VALVE I RESISTANCE WIRE
/ ^v /
TRAP
180°C
HEATER CONTROL
NOTE: ALL LINES BETWEEN
TRAP AND GC
SHOULD BE HEATED
TO 80°C
PURGING DEVICE
FIGURE 4 PURGE-TRAP SYSTEM (DESOR0 MODE)
-------
COIUMN IX If low ON CM»Of»C« •
ttOGIAM 41-C I MINUIH C/MINUII IO 110'C
DIIIC10I HAII ;M A OMIAIINO *| HMO
•IIINIION IIMI MWIUIIt
CH«OMAIOO«AM Of 0 4u,/| SIANDARO
14
It
-------
••I- r* c c •
5U;.3y l'°.- - •"'•' "Ci
VINYl CMIOIIDE * CHLOtOMnMANE
MOMOMETMANE
UDfCHtOIOETHTUNE
OilOKOETMANE
1-1.3. OICNIOROITNTUNE
MfTKTUNt CWOUOE
CHtOROrOlM * «»-1.2.0tCHlOtOElHYliN€
SIOMOCHLOKOMHHANE
1.I.DKHIOIOETHANE
TIICHIOIOETHANE * l.l.2-I«ICHlO«OnHtlENt
••OMODICHlOtOMfTHANE
DtMOMOMEIMANE * Tn«ACHlO*OnMTllNE
l.2-OICHlO*OElMANt
DWIOMOCHlO-CHlO»OTOlUtNt
1.4-aiCMU»O«UTANE * •-MCHIOIOKNZSME
HEXACHLOKOMnADONE
U, «-TIICHLOIOB(NZINE
-------
6MM O.O. HALF-HOLE
CYLINDRICAL SEPTUM
8MM OD.TUBING
9MM LONG
FIGURE 7 MODIFIED VOLUMETRIC FLASK
------- |