ASTM D3871-84(2011)
(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). 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 D2908.
1.4 It is the user's responsibility to assure the validity of the test method for untested matrices.
1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.6 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.
General Information
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: D3871 − 84 (Reapproved 2011)
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 E355 Practice for Gas Chromatography Terms and Relation-
ships
1.1 This test method covers the determination of most
purgeable organic compounds that boil below 200°C and are
3. Terminology
less than 2 % soluble in water. It covers the low µg/L to low
3.1 Definitions—For definitions of terms used in this test
mg/L concentration range (see Section 15 and Appendix X1).
method, refer to Terminology D1129 and Practice E355.
1.2 This test method was developed for the analysis of
3.2 Definitions of Terms Specific to This Standard:
drinking water. It is also applicable to many environmental and
3.2.1 purgeable organic—any organic material that is re-
waste waters when validation, consisting of recovering known
moved from aqueous solution under the purging conditions
concentrations of compounds of interest added to representa-
described in this test method (10.1.1).
tive matrices, is included.
4. Summary of Test Method
1.3 Volatile organic compounds in water at concentrations
above 1000 µg/L may be determined by direct aqueous
4.1 An inert gas is bubbled through the sample to purge
injection in accordance with Practice D2908.
volatilecompoundsfromtheaqueousphase.Thesecompounds
are then trapped in a column containing a suitable sorbent.
1.4 It is the user’s responsibility to assure the validity of the
After purging is complete, trapped components are thermally
test method for untested matrices.
desorbed onto the head of a gas chromatographic column for
1.5 The values stated in SI units are to be regarded as
separation and analysis. Measurement is accomplished with an
standard. No other units of measurement are included in this
appropriate detector.
standard.
5. Significance and Use
1.6 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
5.1 Purgeable organic compounds, including organohalides,
responsibility of the user of this standard to establish appro-
have been identified as contaminants in raw and drinking
priate safety and health practices and determine the applica-
water. These contaminants may be harmful to the environment
bility of regulatory limitations prior to use. Specific precau-
and man. Dynamic headspace sampling is a generally appli-
tionary statements are given in 8.5.5.1.
cable method for concentrating these components prior to gas
chromatographic analysis (1-5). This test method can be used
2. Referenced Documents
to quantitatively determine purgeable organic compounds in
2.1 ASTM Standards: raw source water, drinking water, and treated effluent water.
D1129 Terminology Relating to Water
6. Interferences
D1193 Specification for Reagent Water
6.1 Purgeable compounds that coelute with components of
D2908 Practice for Measuring Volatile Organic Matter in
interest and respond to the detector will interfere with the
Water by Aqueous-Injection Gas Chromatography
chromatographicmeasurement.Likelihoodofinterferencemay
be decreased by using dissimilar columns or a more selective
This test method is under the jurisdiction of ASTM Committee D19 on Water
detector for the chromatographic step.
andisthedirectresponsibilityofSubcommitteeD19.06onMethodsforAnalysisfor
Organic Substances in Water.
7. Apparatus
Current edition approved May 1, 2011. Published June 2011. Originally approved
in 1979. Last previous edition approved in 2003 as D3871 – 84 (2003). DOI: 7.1 Purging Device—Commercial devices are available for
10.1520/D3871-84R11.
this analysis. Either commercial apparatus or the equipment
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 (2011)
described below may be used for this analysis. Devices used minimum. The heat source is concentrated near the base of the
shall be capable of meeting the precision and bias statements desorber so that the internal seals of the body assembly do not
given in 15.1. become damaged by heat. The use of a detachable needle
7.1.1 Glass Purging Device having a capacity of 5 mL is assemblyfromamicrosyringemakesiteasytoreplaceplugged
shown in Fig. A1.1. Construction details are given in Annex or dulled needles.
A1. A glass frit is installed at the base of the sample reservoir 7.3.2.2 The flow controller, PTFE tubing, and stem assem-
toallowfinelydividedgasbubblestopassthroughtheaqueous bly are used to provide the trap-backflush flow. This entire
sample while the sample is restrained above the frit. The assembly is also used to provide gas flow to operate the
sample reservoir is designed to provide maximum bubble purging device.
contact time and efficient mixing.
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
steel packed with a suitable packing. Glass or nickel columns
packed with a suitable sorbent. Traps should be conditioned
before use (Section 11). While other trap designs and sorbent may be required for certain applications. Helium carrier gas
flow is 33 mL/min and a flame ionization detector is used.
materials may be used (see Section 12), the trap and sorbent
described here are recommended and were used to collect 7.4.3 Chromatograph Oven is held at room temperature
duringtrapdesorption,thenrapidlyheatedto60°Candheldfor
precision and bias data. If another trap design or sorbent
material is used, these precision and bias statements should be 4 min. Finally, the temperature is programmed to 170°C at
8°C/min and held for 12 min or until all compounds have
verified. A suitable trap design is 150 mm long by 3.17-mm
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
area. When cool, the vials are sealed with septa, PTFE side
7.3 Desorber consists of a trap heater and an auxiliary
down, and screw capped. Aluminum foil disks may be placed
carriergassourcetobackflushthetrapatelevatedtemperatures
between the septa and screw cap to help minimize contamina-
directly onto the gas-chromatographic column. Desorber 1
tion. Vials are maintained in this capped condition until just
(Fig. A1.3 and Annex A1) is dedicated to one gas
prior to filling with water.
chromatograph, but Desorber 2 can be used as a universal
desorber for many gas chromatographs with a septum-type
7.6 Glass Syringe, 5-mL with two-way syringe valve and
liquid-inlet system.
150 to 200 mm, 20-gage syringe needle.
7.3.1 Desorber 1 is attached directly onto the gas-
chromatograph liquid-inlet system after removing the septum
8. Reagents and Materials
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.
chromatographic column.
7.3.1.2 The flow controller, PTFE tubing, and stem assem-
bly are used to provide the trap-backflush flow. This entire
Pierce No. 13075 Screw Cap System Vials and 12722 Tuf-Bond Discs, Pierce
assembly also provides gas flow to operate the purging device.
Chemical Co., Rockford, IL, have been found satisfactory for this application.
7.3.2 Desorber2(Fig.A1.4andAnnexA1)maybeattached
Reagent Chemicals, American Chemical Society Specifications, American
Chemical Society, Washington, DC. For suggestions on the testing of reagents not
toanygaschromatographbypiercingthegas-chromatographic
listed by the American Chemical Society, see Analar Standards for Laboratory
liquid-inlet septum with the needle.
Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
7.3.2.1 The desorber is assembled in accordance with Fig.
and National Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville,
A1.4 with internal volumes and dead-volume areas held to a MD.
D3871 − 84 (2011)
8.2 Purity of Water—Unless otherwise indicated, Specifica- 8.8 Internal Standard Dosing Solution—From stock stan-
tion D1193, Type II, will be used in this test method. Analyze dardsolutionspreparedasin8.5,addavolumetoprovide1000
a 5-mL aliquot of this water as described in Section 12 before µg of each standard to 45 mL of water contained in a 50-mL
preparing standard solutions. If the blank sample produces volumetric flask, dilute to volume, and mix. Prepare a fresh
interferences for the compounds of interest, purge it free of internal standard dosing solution daily. Dose the internal
volatile contaminants with purge gas (8.9) before using. standard solution into every sample and reference standard
analyzed. It is up to the analyst to choose internal standard
8.3 Dechlorinating Agent—Granular sodium thiosulfate or
compounds appropriate to the analysis.
ascorbic acid.
6 8.9 Purge Gas–Nitrogen or Helium—Take precautions to
8.4 Trap Packings —60/80 mesh chromatographic grade
prevent organic materials that may be present in the purge gas
2,6-diphenyl-p-phenylene oxide and 35 to 60 mesh silica gel.
or laboratory air from contaminating the sample. High-purity
Other packings may be needed for specific determinations.
purge gases (99.99 %) are desirable. Lower quality gases may
8.5 Stock Solutions—Prepare a stock solution (approxi-
be used if impurities are removed, for example by molecular
mately2mg/mL)foreachmaterialbeingmeasured,asfollows:
sieve or low-temperature cold traps, or both.
8.5.1 Fill a 10.0-mL ground glass-stoppered volumetric
flask with approximately 9.8 mL of methyl alcohol.
9. Sampling
8.5.2 Allow the flask to stand unstoppered about 10 min or
9.1 If the water has been chlorinated, add 1 to 2 mg of
until all alcohol wetted surfaces dry.
dechlorinating agent to the sampling vial (7.5) before sam-
8.5.3 Weigh the unstoppered flask to the nearest 0.1 mg.
pling.Whetherchlorinatedornot,fillthevialtooverflowingso
8.5.4 Using a 100-µL syringe, immediately add 6 drops of
that a convex meniscus forms at the top. Place a septum, PTFE
one reference material to the flask, then reweigh. Be sure that
side down, carefully on the opening of the vial, displacing the
the drops fall directly into the alcohol without contacting the
excess water. If an aluminum foil disk is to be used, place it
neck of the flask.
over the septum. Then seal the vial with the screw cap and
8.5.5 Dilute to volume, stopper, then mix by inverting the
invert to verify the seal by demonstrating the absence of air
flask several times.
bubbles.
8.5.5.1 Warning—Because the reference materials are
likelytobetoxicandvolatile,prepareconcentratedsolutionsin NOTE 2—The sample should be headspace-free at this time. A small
bubble may form if the vial is stored more than a few hours. Analyze the
a hood. It is advisable to wear rubber gloves and use an
sample within a few hours if possible. If storage is necessary, maintain the
approved respirator when handling volatile toxic materials.
sample temperature at 0 to 4°C until analyzed. Retighten the screw cap
8.5.6 Calculate the concentration in micrograms per millili-
after the sample is chilled. Storage over charcoal will minimize contami-
tre from the net gain in weight.
nation. Data on compounds tested showed them to be stable for at least 15
days.
8.5.7 Store the solutions at 4°C. Warm to room temperature
before use.
10. Calibration and Standardization
NOTE 1—Standard solutions prepared in methyl alcohol are generally
10.1 Calibrate the system by analyzing replicate aliquots of
stable up to 4 weeks when stored under these conditions. Discard them
after that time has elapsed.
the quality check sample (8.7), to which 5 µL of the internal
standard dosing solution (8.8) have been added, as described in
8.6 Working Standard (approximately 100 µg/mL)—
Section 12. Replicate analyses permit the analyst to determine
Prepare a working standard containing each compound to be
precision for each component.
tested, a
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