ASTM D3871-84(2003)
(Test Method)Standard Test Method for Purgeable Organic Compounds in Water Using Headspace Sampling
Standard Test Method for Purgeable Organic Compounds in Water Using Headspace Sampling
SIGNIFICANCE AND USE
Purgeable organic compounds, including organohalides, have been identified as contaminants in raw and drinking water. These contaminants may be harmful to the environment and man. Dynamic headspace sampling is a generally applicable method for concentrating these components prior to gas chromatographic analysis (1 to 5).5 This test method can be used to quantitatively determine purgeable organic compounds in raw source water, drinking water, and treated effluent water.
SCOPE
1.1 This test method covers the determination of most purgeable organic compounds that boil below 200°C and are less than 2 % soluble in water. It covers the low μg/L to low mg/L concentration range (see Section 15 and Appendix X1).
1.2 This test method was developed for the analysis of drinking water. It is also applicable to many environmental and waste waters when validation, consisting of recovering known concentrations of compounds of interest added to representative matrices, is included.
1.3 Volatile organic compounds in water at concentrations above 1000 μg/L may be determined by direct aqueous injection in accordance with Practice D 2908.
1.4 It is the user's responsibility to assure the validity of the test method for untested matrices.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Specific precautionary statements are given in 8.5.5.1.
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Designation:D3871–84 (Reapproved 2003)
Standard Test Method for
Purgeable Organic Compounds in Water Using Headspace
Sampling
This standard is issued under the fixed designation D3871; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 3.2 Description of Term Specific to This Standard:
3.2.1 purgeable organic—any organic material that is re-
1.1 This test method covers the determination of most
moved from aqueous solution under the purging conditions
purgeable organic compounds that boil below 200°C and are
described in this test method (10.1.1).
less than 2 % soluble in water. It covers the low µg/L to low
mg/L concentration range (see Section 15 and Appendix X1).
4. Summary of Test Method
1.2 This test method was developed for the analysis of
4.1 An inert gas is bubbled through the sample to purge
drinking water. It is also applicable to many environmental and
volatilecompoundsfromtheaqueousphase.Thesecompounds
waste waters when validation, consisting of recovering known
are then trapped in a column containing a suitable sorbent.
concentrations of compounds of interest added to representa-
After purging is complete, trapped components are thermally
tive matrices, is included.
desorbed onto the head of a gas chromatographic column for
1.3 Volatile organic compounds in water at concentrations
separation and analysis. Measurement is accomplished with an
above 1000 µg/L may be determined by direct aqueous
appropriate detector.
injection in accordance with Practice D2908.
1.4 It is the user’s responsibility to assure the validity of the
5. Significance and Use
test method for untested matrices.
5.1 Purgeable organic compounds, including organohalides,
1.5 This standard does not purport to address all of the
have been identified as contaminants in raw and drinking
safety concerns, if any, associated with its use. It is the
water. These contaminants may be harmful to the environment
responsibility of the user of this standard to establish appro-
and man. Dynamic headspace sampling is a generally appli-
priate safety and health practices and determine the applica-
cable method for concentrating these components prior to gas
bility of regulatory limitations prior to use. Specific precau-
chromatographic analysis (1 to 5). This test method can be
tionary statements are given in 8.5.5.1.
used to quantitatively determine purgeable organic compounds
in raw source water, drinking water, and treated effluent water.
2. Referenced Documents
2.1 ASTM Standards:
6. Interferences
D1129 Terminology Relating to Water
6.1 Purgeable compounds that coelute with components of
D1193 Specification for Reagent Water
interest and respond to the detector will interfere with the
D2908 Practice for Measuring Volatile Organic Matter in
chromatographicmeasurement.Likelihoodofinterferencemay
Water by Aqueous-Injection Gas Chromatography
be decreased by using dissimilar columns or a more selective
E355 Practice for Gas Chromatography Terms and Rela-
detector for the chromatographic step.
tionships
7. Apparatus
3. Terminology
7.1 Purging Device—Commercial devices are available for
3.1 Definitions—For definitions of terms used in this test
this analysis. Either commercial apparatus or the equipment
method, refer to Terminology D1129 and Practice E355.
described below may be used for this analysis. Devices used
shall be capable of meeting the precision and bias statements
This test method is under the jurisdiction of ASTM Committee D19 on Water
given in 15.1.
andisthedirectresponsibilityofSubcommitteeD19.06onMethodsforAnalysisfor
7.1.1 Glass Purging Device having a capacity of 5 mL is
Organic Substances in Water.
shown in Fig. A1.1. Construction details are given in Annex
Current edition approved Jan. 10, 2003. Published January 2003. Originally
´1
approved in 1979. Last previous edition approved in 1995 as D3871 – 84 (1995) .
A1. A glass frit is installed at the base of the sample reservoir
DOI: 10.1520/D3871-84R03.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on The boldface numbers in parentheses refer to the references at the end of this
the ASTM website. test method.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D3871–84 (2003)
toallowfinelydividedgasbubblestopassthroughtheaqueous 7.3.2.2 The flow controller, PTFE tubing, and stem assem-
sample while the sample is restrained above the frit. The bly are used to provide the trap-backflush flow. This entire
sample reservoir is designed to provide maximum bubble assembly is also used to provide gas flow to operate the
contact time and efficient mixing. purging device.
7.4 Gas Chromatograph equipped with a suitable detector,
7.1.2 Gaseous volumes above the sample reservoir are kept
such as flame ionization, electrolytic conductivity, microcou-
to a minimum to provide efficient transfer and yet large enough
lometric (halide mode), flame photometric, electron capture, or
to allow sufficient space for foams to disperse. Inlet and exit
mass spectrometer.
ports are constructed from 6.4-mm ( ⁄4-in.) outside diameter
7.4.1 The gas chromatographic conditions described below
medium-wall tubing so that leak-free removable connections
are recommended and were used to obtain precision and bias
can be made using“ finger-tight” compression fittings contain-
data (Section 15). If other column conditions are used, the
ing plastic ferrules. The optional foam trap is used to control
analyst must demonstrate that the precision and bias achieved
occasional samples that foam excessively.
are at least as good as that presented in Section 15.
7.2 Trap—Ashortsectionofstainlesssteelorglasstubingis
7.4.2 Column is 2.4 m by 2.4-mm inside diameter stainless
packed with a suitable sorbent. Traps should be conditioned
steel packed with a suitable packing. Glass or nickel columns
before use (Section 11). While other trap designs and sorbent
may be required for certain applications. Helium carrier gas
materials may be used (see Section 12), the trap and sorbent
flow is 33 mL/min and a flame ionization detector is used.
described here are recommended and were used to collect
7.4.3 Chromatograph Oven is held at room temperature
precision and bias data. If another trap design or sorbent
duringtrapdesorption,thenrapidlyheatedto60°Candheldfor
material is used, these precision and bias statements should be
4 min. Finally, the temperature is programmed to 170°C at
verified. A suitable trap design is 150 mm long by 3.17-mm
8°C/min and held for 12 min or until all compounds have
outsidediameter(2.54-mminsidediameter).Thefront100mm
eluted.
is packed with 60 to 80 mesh 2,6-diphenyl-p-phenylene oxide
7.5 Sampling Vials, glass, 45-mL, sealed with PTFE-faced
followed by 50 mm of 35 to 60-mesh silica gel. One trap
septa. Vial caps must be open-top screw caps to prevent vial
design is shown in Fig. A1.2, with details in Annex A1. The
breakage. The vials, septa, and caps are washed with detergent
body assembly acts as a seal for the exit end of the trap. The
and hot water and rinsed with tap water and organic free water.
modified stem assembly is used to seal the inlet end of the trap
The vials and septa are then heated to 105°C for1hand
when it is not in use.
allowed to cool to room temperature in a contaminant-free
7.3 Desorber consists of a trap heater and an auxiliary
area. When cool, the vials are sealed with septa, PTFE side
carriergassourcetobackflushthetrapatelevatedtemperatures
down, and screw capped. Aluminum foil disks may be placed
directly onto the gas-chromatographic column. Desorber 1
between the septa and screw cap to help minimize contamina-
(Fig. A1.3 and Annex A1) is dedicated to one gas chromato-
tion. Vials are maintained in this capped condition until just
graph, but Desorber 2 can be used as a universal desorber for
prior to filling with water.
many gas chromatographs with a septum-type liquid-inlet
7.6 Glass Syringe, 5-mL with two-way syringe valve and
system.
150 to 200 mm, 20-gage syringe needle.
7.3.1 Desorber 1 is attached directly onto the gas-
8. Reagents and Materials
chromatograph liquid-inlet system after removing the septum
nut, the septum, and the internal injector parts. The modified
8.1 Purity of Reagents—Reagent grade chemicals shall be
bodyassemblyisscrewedontotheinletsystemusingthePTFE
used in all tests. Unless otherwise indicated, it is intended that
gasket as a seal. A plug is attached to one of the stem
all reagents shall conform to the specifications of the Commit-
assemblies.
tee onAnalytical Reagents of theAmerican Chemical Society.
7.3.1.1 The assembled parts, simply called “the plug,” are Other grades may be used, provided it is first ascertained that
used to seal the desorber whenever the trap is removed to the reagent is of sufficiently high purity to permit its use
maintain the flow of carrier gas through the gas- without lessening the accuracy of the determination.
8.2 Purity of Water—Unless otherwise indicated, Specifica-
chromatographic column.
tion D1193, Type II, will be used in this test method. Analyze
7.3.1.2 The flow controller, PTFE tubing, and stem assem-
a 5-mL aliquot of this water as described in Section 12 before
bly are used to provide the trap-backflush flow. This entire
preparing standard solutions. If the blank sample produces
assembly also provides gas flow to operate the purging device.
interferences for the compounds of interest, purge it free of
7.3.2 Desorber 2 (Fig. A1.4 and Annex A1) may be at-
volatile contaminants with purge gas (8.9) before using.
tached to any gas chromatograph by piercing the gas-
chromatographic liquid-inlet septum with the needle.
7.3.2.1 The desorber is assembled in accordance with Fig.
Pierce No. 13075 Screw Cap System Vials and 12722 Tuf-Bond Discs, Pierce
A1.4 with internal volumes and dead-volume areas held to a
Chemical Co., Rockford, IL, have been found satisfactory for this application.
minimum. The heat source is concentrated near the base of the
Reagent Chemicals, American Chemical Society Specifications, American
Chemical Society, Washington, DC. For suggestions on the testing of reagents not
desorber so that the internal seals of the body assembly do not
listed by the American Chemical Society, see Analar Standards for Laboratory
become damaged by heat. The use of a detachable needle
Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
assemblyfromamicrosyringemakesiteasytoreplaceplugged
and National Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville,
or dulled needles. MD.
D3871–84 (2003)
8.3 Dechlorinating Agent—Granular sodium thiosulfate or analyzed. It is up to the analyst to choose internal standard
ascorbic acid. compounds appropriate to the analysis.
8.4 Trap Packings —60/80 mesh chromatographic grade 8.9 Purge Gas–Nitrogen or Helium—Take precautions to
2,6-diphenyl-p-phenylene oxide and 35 to 60 mesh silica gel. prevent organic materials that may be present in the purge gas
Other packings may be needed for specific determinations. or laboratory air from contaminating the sample. High-purity
8.5 Stock Solutions—Prepare a stock solution (approxi- purge gases (99.99 %) are desirable. Lower quality gases may
mately2mg/mL)foreachmaterialbeingmeasured,asfollows: be used if impurities are removed, for example by molecular
8.5.1 Fill a 10.0-mL ground glass-stoppered volumetric sieve or low-temperature cold traps, or both.
flask with approximately 9.8 mL of methyl alcohol.
9. Sampling
8.5.2 Allow the flask to stand unstoppered about 10 min or
until all alcohol wetted surfaces dry.
9.1 If the water has been chlorinated, add 1 to 2 mg of
8.5.3 Weigh the unstoppered flask to the nearest 0.1 mg.
dechlorinating agent to the sampling vial (7.5) before sam-
8.5.4 Using a 100-µL syringe, immediately add 6 drops of
pling.Whetherchlorinatedornot,fillthevialtooverflowingso
one reference material to the flask, then reweigh. Be sure that
that a convex meniscus forms at the top. Place a septum, PTFE
the drops fall directly into the alcohol without contacting the
side down, carefully on the opening of the vial, displacing the
neck of the flask.
excess water. If an aluminum foil disk is to be used, place it
8.5.5 Dilute to volume, stopper, then mix by inverting the
over the septum. Then seal the vial with the screw cap and
flask several times.
invert to verify the seal by demonstrating the absence of air
8.5.5.1 Warning—Because the reference materials are
bubbles.
likelytobetoxicandvolatile,prepareconcentratedsolutionsin
NOTE 2—The sample should be headspace-free at this time. A small
a hood. It is advisable to wear rubber gloves and use an
bubble may form if the vial is stored more than a few hours. Analyze the
approved respirator when handling volatile toxic materials.
sample within a few hours if possible. If storage is necessary, maintain the
8.5.6 Calculate the concentration in micrograms per millili-
sample temperature at 0 to 4°C until analyzed. Retighten the screw cap
tre from the net gain in weight.
after the sample is chilled. Storage over charcoal will minimize contami-
8.5.7 Store the solutions at 4°C. Warm to room temperature nation. Data on compounds tested showed them to be stable for at least 15
days.
before use.
NOTE 1—Standard solutions prepared in methyl alcohol are generally
10. Calibration and Standardization
stable up to 4 weeks when stored under these conditions. Discard them
10.1 Calibrate the system by analyzing replicate aliquots of
after that time has elapsed.
the quality check sample (8.7), to which 5 µL of the internal
8.6 Working Standard (approximately 100 µg/mL)—
standard dosing solution (8.8) have been added, as described in
Prepare a working standard containing each compound to be
Section 12. Replicate analyses permit the analyst to determine
tested, as follows.
precision for each component.
8.6.1 Fill a 100-mL volumetric flask approximately three
10.1.1 Quantitative purging of each component, although
fourths full of methanol or acetone.
desirable, is not required for successful analyses using this
8.6.2 Pipet 1 mL of the stock solution (8.5) of each
procedure. However, purging must be sufficiently reproducible
compound of interest into the flask, using subsurface addition.
to permit correction for incomplete recovery
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