ASTM D3871-84(2024)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D3871 − 84 (Reapproved 2024)
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 2. Referenced Documents
1.1 This test method covers the determination of most 2.1 ASTM Standards:
purgeable organic compounds that boil below 200 °C and are D1129 Terminology Relating to Water
less than 2 % soluble in water. It covers the low μg/L to low D1193 Specification for Reagent Water
mg/L concentration range (see Section 15 and Appendix X1). D2908 Practice for Measuring Volatile Organic Matter in
Water by Aqueous-Injection Gas Chromatography
1.2 This test method was developed for the analysis of
E355 Practice for Gas Chromatography Terms and Relation-
drinking water. It is also applicable to many environmental and
ships
waste waters when validation, consisting of recovering known
concentrations of compounds of interest added to representa-
3. Terminology
tive matrices, is included.
3.1 Definitions:
1.3 Volatile organic compounds in water at concentrations
3.1.1 For definitions of terms used in this standard, refer to
above 1000 μg/L may be determined by direct aqueous
Terminology D1129 and Practice E355.
injection in accordance with Practice D2908.
3.2 Definitions of Terms Specific to This Standard:
1.4 It is the user’s responsibility to assure the validity of the
3.2.1 purgeable organic, n—any organic material that is
test method for untested matrices.
removed from aqueous solution under the purging conditions
1.5 The values stated in SI units are to be regarded as described in this test method (10.1.1).
standard. No other units of measurement are included in this
4. Summary of Test Method
standard.
4.1 An inert gas is bubbled through the sample to purge
1.6 This standard does not purport to address all of the
volatile compounds from the aqueous phase. These compounds
safety concerns, if any, associated with its use. It is the
are then trapped in a column containing a suitable sorbent.
responsibility of the user of this standard to establish appro-
After purging is complete, trapped components are thermally
priate safety, health, and environmental practices and deter-
desorbed onto the head of a gas chromatographic column for
mine the applicability of regulatory limitations prior to use.
separation and analysis. Measurement is accomplished with an
Specific precautionary statements are given in 8.5.5.1.
appropriate detector.
1.7 This international standard was developed in accor-
dance with internationally recognized principles on standard-
5. Significance and Use
ization established in the Decision on Principles for the
5.1 Purgeable organic compounds, including organohalides,
Development of International Standards, Guides and Recom-
have been identified as contaminants in raw and drinking
mendations issued by the World Trade Organization Technical
water. These contaminants may be harmful to the environment
Barriers to Trade (TBT) Committee.
and man. Dynamic headspace sampling is a generally appli-
cable method for concentrating these components prior to gas
This test method is under the jurisdiction of ASTM Committee D19 on Water
and is the direct responsibility of Subcommittee D19.06 on Methods for Analysis for
Organic Substances in Water. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved April 1, 2024. Published April 2024. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1979. Last previous edition approved in 2017 as D3871 – 84 (2017). Standards volume information, refer to the standard’s Document Summary page on
DOI: 10.1520/D3871-84R24. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D3871 − 84 (2024)
chromatographic analysis (1-5). This test method can be used 7.3.1 Desorber 1 is attached directly onto the gas-
to quantitatively determine purgeable organic compounds in chromatograph liquid-inlet system after removing the septum
raw source water, drinking water, and treated effluent water. nut, the septum, and the internal injector parts. The modified
body assembly is screwed onto the inlet system using the PTFE
6. Interferences
gasket as a seal. A plug is attached to one of the stem
assemblies.
6.1 Purgeable compounds that coelute with components of
7.3.1.1 The assembled parts, simply called “the plug,” are
interest and respond to the detector will interfere with the
used to seal the desorber whenever the trap is removed to
chromatographic measurement. Likelihood of interference may
maintain the flow of carrier gas through the gas-
be decreased by using dissimilar columns or a more selective
chromatographic column.
detector for the chromatographic step.
7.3.1.2 The flow controller, PTFE tubing, and stem assem-
7. Apparatus
bly are used to provide the trap-backflush flow. This entire
assembly also provides gas flow to operate the purging device.
7.1 Purging Device—Commercial devices are available for
7.3.2 Desorber 2 (Fig. A1.4 and Annex A1) may be attached
this analysis. Either commercial apparatus or the equipment
to any gas chromatograph by piercing the gas-chromatographic
described below may be used for this analysis. Devices used
liquid-inlet septum with the needle.
shall be capable of meeting the precision and bias statements
7.3.2.1 The desorber is assembled in accordance with Fig.
given in 15.1.
A1.4 with internal volumes and dead-volume areas held to a
7.1.1 Glass Purging Device having a capacity of 5 mL is
minimum. The heat source is concentrated near the base of the
shown in Fig. A1.1. Construction details are given in Annex
desorber so that the internal seals of the body assembly do not
A1. A glass frit is installed at the base of the sample reservoir
become damaged by heat. The use of a detachable needle
to allow finely divided gas bubbles to pass through the aqueous
sample while the sample is restrained above the frit. The assembly from a microsyringe makes it easy to replace plugged
or dulled needles.
sample reservoir is designed to provide maximum bubble
contact time and efficient mixing.
7.3.2.2 The flow controller, PTFE tubing, and stem assem-
7.1.2 Gaseous volumes above the sample reservoir are kept bly are used to provide the trap-backflush flow. This entire
to a minimum to provide efficient transfer and yet large enough
assembly is also used to provide gas flow to operate the
to allow sufficient space for foams to disperse. Inlet and exit purging device.
ports are constructed from 6.4-mm ( ⁄4-in.) outside diameter
7.4 Gas Chromatograph equipped with a suitable detector,
medium-wall tubing so that leak-free removable connections
such as flame ionization, electrolytic conductivity, microcou-
can be made using“ finger-tight” compression fittings contain-
lometric (halide mode), flame photometric, electron capture, or
ing plastic ferrules. The optional foam trap is used to control
mass spectrometer.
occasional samples that foam excessively.
7.4.1 The gas chromatographic conditions described below
7.2 Trap—A short section of stainless steel or glass tubing is
are recommended and were used to obtain precision and bias
packed with a suitable sorbent. Traps should be conditioned
data (Section 15). If other column conditions are used, the
before use (Section 11). While other trap designs and sorbent
analyst must demonstrate that the precision and bias achieved
materials may be used (see Section 12), the trap and sorbent
are at least as good as that presented in Section 15.
described here are recommended and were used to collect
7.4.2 Column is 2.4 m by 2.4 mm inside diameter stainless
precision and bias data. If another trap design or sorbent
steel packed with a suitable packing. Glass or nickel columns
material is used, these precision and bias statements should be
may be required for certain applications. Helium carrier gas
verified. A suitable trap design is 150 mm long by 3.17 mm
flow is 33 mL/min and a flame ionization detector is used.
outside diameter (2.54 mm inside diameter). The front 100 mm
7.4.3 Chromatograph Oven is held at room temperature
is packed with 60 to 80 mesh 2,6-diphenyl-p-phenylene oxide
during trap desorption, then rapidly heated to 60 °C and held
followed by 50 mm of 35 to 60 mesh silica gel. One trap design
for 4 min. Finally, the temperature is programmed to 170 °C at
is shown in Fig. A1.2, with details in Annex A1. The body
8 °C ⁄min and held for 12 min or until all compounds have
assembly acts as a seal for the exit end of the trap. The
eluted.
modified stem assembly is used to seal the inlet end of the trap
7.5 Sampling Vials, glass, 45 mL, sealed with PTFE-faced
when it is not in use.
septa. Vial caps must be open-top screw caps to prevent vial
7.3 Desorber consists of a trap heater and an auxiliary
breakage. The vials, septa, and caps are washed with detergent
carrier gas source to backflush the trap at elevated temperatures
and hot water and rinsed with tap water and organic free water.
directly onto the gas-chromatographic column. Desorber 1
The vials and septa are then heated to 105 °C for 1 h and
(Fig. A1.3 and Annex A1) is dedicated to one gas
allowed to cool to room temperature in a contaminant-free
chromatograph, but Desorber 2 can be used as a universal
area. When cool, the vials are sealed with septa, PTFE side
desorber for many gas chromatographs with a septum-type
down, and screw capped. Aluminum foil disks may be placed
liquid-inlet system.
3 4
The boldface numbers in parentheses refer to a list of references at the end of Pierce No. 13075 Screw Cap System Vials and 12722 Tuf-Bond Discs, Pierce
this standard. Chemical Co., Rockford, IL, have been found satisfactory for this application.
D3871 − 84 (2024)
NOTE 1—Standard solutions prepared in methyl alcohol are generally
between the septa and screw cap to help minimize contamina-
stable up to 4 weeks when stored under these conditions. Discard them
tion. Vials are maintained in this capped condition until just
after that time has elapsed.
prior to filling with water.
8.6 Working Standard (approximately 100 μg/mL)—
7.6 Glass Syringe, 5 mL with two-way syringe valve and
Prepare a working standard containing each compound to be
150 mm to 200 mm, 20 gauge syringe needle.
tested, as follows.
8.6.1 Fill a 100 mL volumetric flask approximately three
8. Reagents and Materials
fourths full of methanol or acetone.
8.1 Purity of Reagents—Reagent grade chemicals shall be
8.6.2 Pipet 1 mL of the stock solution (8.5) of each
used in all tests. Unless otherwise indicated, it is intended that
compound of interest into the flask, using subsurface addition.
all reagents shall conform to the specifications of the Commit-
Stopper the flask except when actually transferring solutions.
tee on Analytical Reagents of the American Chemical Society.
8.6.3 After adding standard stock solutions, dilute to the
Other grades may be used, provided it is first ascertained that
mark with solvent and mix thoroughly. Immediately transfer
the reagent is of sufficiently high purity to permit its use
this solution to a clean vial (7.5) by filling to overflowing and
without lessening the accuracy of the determination.
sealing with a septum, PTFE side down, and screw cap.
8.2 Purity of Water—Unless otherwise indicated, Specifica-
8.7 Quality Check Sample (approximately 20 μg/L)—Just
tion D1193, Type II, will be used in this test method. Analyze
prior to calibration, prepare a quality check sample by dosing
a 5 mL aliquot of this water as described in Section 12 before
20.0 μL of the working standard solution (8.6) into 100.0 mL
preparing standard solutions. If the blank sample produces
of water.
interferences for the compounds of interest, purge it free of
8.8 Internal Standard Dosing Solution—From stock stan-
volatile contaminants with purge gas (8.9) before using.
dard solutions prepared as in 8.5, add a volume to provide
8.3 Dechlorinating Agent—Granular sodium thiosulfate or
1000 μg of each standard to 45 mL of water contained in a
ascorbic acid.
50 mL volumetric flask, dilute to volume, and mix. Prepare a
8.4 Trap Packings —60/80 mesh chromatographic grade fresh internal standard dosing solution daily. Dose the internal
2,6-diphenyl-p-phenylene oxide and 35 to 60 mesh silica gel.
standard solution into every sample and reference standard
Other packings may be needed for specific determinations.
analyzed. It is up to the analyst to choose internal standard
compounds appropriate to the analysis.
8.5 Stock Solutions—Prepare a stock solution (approxi-
mately 2 mg/mL) for each material being measured, as follows:
8.9 Purge Gas–Nitrogen or Helium—Take precautions to
8.5.1 Fill a 10.0 mL ground glass-stoppered volumetric
prevent organic materials that may be present in the purge gas
flask with approximately 9.8 mL of methyl alcohol.
or laboratory air from contaminating the sample. High-purity
8.5.2 Allow the flask to stand unstoppered about 10 min or
purge gases (99.99 %) are desirable. Lower quality gases may
until all alcohol wetted surfaces dry.
be used if impurities are removed, for example by molecular
8.5.3 Weigh the unstoppered flask to the nearest 0.1 mg.
sieve or low-temperature cold traps, or both.
8.5.4 Using a 100 μL syringe, immediately add 6 drops of
one reference material to the flask, then reweigh. Be sure that 9. Sampling
the drops fall directly into the alcohol without contacting the
9.1 If the water has been chlorinated, add 1 mg to 2 mg of
neck of the flask.
dechlorinating agent to the sampling vial (7.5) before sam-
8.5.5 Dilute to volume, stopper, then mix by inverting the
pling. Whether chlorinated or not, fill the vial to overflowing so
flask several times.
that a convex meniscus forms at the top. Place a septum, PTFE
8.5.5.1 Warning—Because the reference materials are
side down, carefully on the opening of the vial, displacing the
likely to be toxic and volatile, prepare concentrated solutions in
excess water. If an aluminum foil disk is to be used, place it
a hood. It is advisable to wear rubber gloves and use an
over the septum. Then seal the vial with the screw cap and
approved respirator when handling volatile toxic materials.
inv
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