ASTM D3687-95

NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
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Designation: D 3687 – 95 An American National Standard
Standard Practice for
Analysis of Organic Compound Vapors Collected by the
Activated Charcoal Tube Adsorption Method
This standard is issued under the fixed designation D 3687; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope 2.3 OSHA Standard:
29 CFR 1910 General and Industrial OSHA Safety and
1.1 This practice covers the applications of methods for the
Health Standard
desorption and gas chromatographic determination of organic
vapors that have been adsorbed from air in sampling tubes
3. Terminology
packed with activated charcoal.
3.1 Definitions:
1.2 This practice is complementary to Practice D 3686.
3.1.1 For definitions of terms used in this practice, refer to
1.3 This practice is applicable for analysis of samples taken
Terminology D 1356, and E 355.
from workplace or other atmospheres, provided that the con-
3.1.2 relative retention time (RRT)—a ratio of RTs’ for two
taminant adsorbs onto charcoal and that it can be analyzed by
chemicals for the same chromatographic column and carrier
gas chromatography. A partial list of organic compounds for
gas flow rate, where the denominator represents a reference
which this method is applicable is given in A1 in Practice
chemical.
D 3686.
3.1.3 retention time (RT)—time to elute a specific chemical
1.4 Organic compounds of multicomponent samples may
from a chromatographic column, for a specific carrier gas flow
mutually interfere during analysis. Methods to resolve inter-
rate, measured from the time the chemical is injected into the
ferences are given in Section 6.
gas stream to when it appears at the detector.
1.5 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
4. Summary of Practice
responsibility of the user of this standard to establish appro-
4.1 Organic vapors, which have been collected on activated
priate safety and health practices and determine the applica-
charcoal and eluted therefrom with carbon disulfide or other
bility of regulatory limitations prior to use. Specific precau-
appropriate desorbent, are determined by gas-liquid chroma-
tions are given in 8.1.4.2 and Annex A1.
tography, using a flame ionization detector and other appropri-
2. Referenced Documents ate detectors.
4.2 Interferences resulting from the analytes having similar
2.1 ASTM Standards:
retention times during gas-liquid chromatography are resolved
D 1356 Terminology Relating to Sampling and Analysis of
2 by improving the resolution or separation, such as by changing
Atmospheres
the chromatographic column or operating parameters, or by
D 3686 Practice for Sampling Atmospheres to Collect Or-
fractionating the sample by solvent extraction.
ganic Compound Vapors (Activated Charcoal Tube Ad-
2 4.3 Peaks are identified using techniques such as GC/MS
sorption Method)
and dual column chromatography.
E 355 Practice for Gas Chromatography Terms and Rela-
tionships
5. Significance and Use
2.2 NIOSH Standards:
5.1 Promulgations by the Federal Occupational Safety and
CDC-99-74-45 Documentation of NIOSH Validation
Health Administration (OSHA) in 29 CFR 1910 designate that
Tests
4 certain organic compounds must not be present in workplace
Manual of Analytical Methods, 2nd Ed.
atmospheres at concentrations above specified values.
5.2 This practice, when used in conjunction with Practice
D 3686, will promote needed accuracy and precision in the
This practice is under the jurisdiction of ASTM Committee D-22 on Sampling
determination of airborne concentrations of many of the
and Analysis of Atmospheres, and is the direct responsibility of Subcommittees
D 22.04 on Analysis of Workplace Atmospheres. organic chemicals given in 29 CFR 1910, CDC-99-74-45, and
Current edition approved Feb. 15, 1995. Published April 1995. Originally
the Manual of Analytical Methods. It can be used to determine
published as D 3687 – 78. Last previous edition D 3687 – 89.
Annual Book of ASTM Standards, Vol 11.03.
Annual Book of ASTM Standards, Vol 14.02.
4 5
Available from the U.S. Department of Commerce, National Technical Infor- Available from Superintendent of Documents, U.S. Government Printing
mation Service, Port Royal Road, Springfield, VA 22161. Office, Washington, DC 20402.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
D 3687
worker exposures to these chemicals, provided appropriate 7.3 Microsyringes, two or more 10-μL volume.
sampling periods are used. 7.4 Vials, 5-mL serum, fitted with caps lined with TFE-
5.3 A partial list of chemicals for which this practice is fluorocarbon.
applicable is given in A1 of Practice D 3686, along with their
8. Calibration
OSHA Permissible Exposure Limits.
8.1 Preparation of Gas Chromatograph:
6. Interferences
8.1.1 Install the selected column.
6.1 Any gas chromatographic separation that involves a
8.1.2 Check the system for leaks as prescribed by GC
mixture of polar and nonpolar compounds is confronted with
manufacturer.
serious problems due to peak superimposition. In many indus-
8.1.3 Select a carrier gas flow compatible with the detector
trial operations, both nonpolar compounds, such as mixed
and column selected for the separation.
aliphatic petroleum hydrocarbons, and polar substances, such
8.1.4 Calibrate the chromatographic column to determine
as aromatic hydrocarbons, amines, oxygenated compounds and
the relative retention times (RRTs) of the various compounds
sometimes halogenated compounds, may be used and found in
of interest.
the workplace atmosphere. It is rarely the case that a single
8.1.4.1 Select a reference solvent which will serve as a
organic solvent vapor may be expected in a workplace atmo-
benchmark.
sphere where organic solvents are being used.
8.1.4.2 Prepare a 0.05 % solution of this solvent (volume/
6.2 Such interferences are frequently resolved by changing
volume) in chromatographic grade carbon disulfide (CS ).
the type of column, length of column, or operating conditions,
When kept in a properly closed container (see 7.4) and
to improve resolution of separation of compounds.
refrigerated when not in use, some solutions will keep for
6.3 General approaches which can be followed are given
several weeks (3).
below:
NOTE 1—Warning: Carbon disulfide is toxic and explosive, as are
6.3.1 Generally unknown samples are analyzed using at
many of the organic compounds to be analyzed. Work with these
least two columns of different polarity.
chemicals must be done in a properly operating laboratory hood.
6.3.2 As a general guide to practice, nonpolar substrates,
8.1.4.3 Into a clean 10-μL syringe draw 2 μL of CS . Draw
such as the silicones, tend to separate according to the boiling
the CS into the barrel of the syringe until the air bubble
points of the compounds, whereas polar column separations are
appears at the 1-μL mark. Check the nominal volume of CS ;
influenced more by the polarity of the compounds.
it should be about 2 μL. If it is not, repeat the process until the
6.3.3 A single wide bore capillary column can replace
proper volume is present.
several specialized packed columns and provide better sample
8.1.4.4 Draw 2 μL of 0.05 % benzene (or other reference
resolution in significantly less time. Application of these
chemical) in CS into the syringe and then into the barrel in
columns minimizes operational changes required to achieve
accordance with 8.1.4.3. The barrel should now contain 2μ L of
peak resolution.
CS , a small bubble of air, and 2 μL of 0.05 % solution of
6.4 Selective solvent stripping techniques have been used
benzene in CS .
successfully to make clean and fast separations of polar,
nonpolar and oxygenated compounds. A general guideline is NOTE 2—Two microlitres of an 0.05 % v/v solution of any solute in a
solvent will contain, in micrograms, the numerical equivalent of the
given in Annex A1 and detailed procedures are given in Refs (1
density of the solute. For example, 2 μL of an 0.05 % solution of benzene
and 2).
contains 0.879 μg of benzene. The practical density of benzene is 0.879 at
7. Apparatus 25°C.
7.1 Gas Chromatograph (GC), having a flame ionization 8.1.4.5 Inject the contents of the syringe into the gas-
detector and either an isothermally controlled or temperature
chromatographic column. (See 8.1.4.3-8.1.4.5 describing the
programmed heating oven. solvent-flush technique referred to in this practice.) Injection
7.2 A variety of packed and capillary columns are suitable.
by means of a GC autosampler is acceptable in most cases.
Two suitable packed columns are a 10 ft stainless steel column, 8.1.4.6 Record the chromatogram of the 0.05 % benzene
⁄8 in. ID packed with 10 % free fatty acid phase (FFAP)
standard in CS using an integrator or strip chart recorder.
substrate on 80/100 mesh acid washed Chromosorb W and a 8.1.4.7 The time between the injection of benzene onto the
nonpolar column containing 10 % methyl silicone substrate on
chromatographic column and peak maximum is the retention
the same support material in a similar column as given above.
time (RT) for benzene.
Alternatively, 35 % diphenyl, 65 % dimethyl polysiloxane and
8.1.4.8 Retention times may be determined manually by
Carbowax 20 M wide bore capillary columns (0.53 and 0.75
observing the time required for a compound to pass through the
mm) may be used in place of the packed columns. These chromatographic column using a stop watch or by measuring
columns are available in 30 and 60 m lengths.
the distance from the starting point to peak maximum shown
on the strip chart. Alternatively an electronic integrator may be
6 used to determine RTs. Most modern gas chromatographs are
The boldface numbers in parentheses refer to the list of references at the end of
this standard.
“Chromosorb W,” a trademark of the Johns-Manville Products Corp., or
equivalent has been found satisfactory for this purpose. A. H. Thomas Catalog No. 5569-E 10 or equivalent has been found satisfactory.
8 10
“Carbowax,” a trademark of the Union Carbide Co., or equivalent has been Benzene is used in this practice as the reference chemical for the purposes of
found satisfactory for this purpose. illustration, but a less toxic chemical such as toluene could be used.
D 3687
TABLE 1 Relative Retention Times (RRTs) for a Group of
equipped with electronic integrators that can accurately mea-
Common Organic Compounds
sure RTs’ within a hundredth of a minute.
8.1.4.9 For the same conditions of operation (carrier gas- NOTE 1—Column: 20-ft, ⁄8-in. outside diameter, stainless steel column
(20 m) packed with 10 % Carbowax on 80/100 mesh Chromosorb W.
flow rate, column temperature, column characteristics) the RT
Oven: Isothermal at 95°C.
may be considered a constant.
(All data relative to the Retention Time of Benzene 5 1.000. RRTs
8.1.4.10 Maintain a continuing record of RTs for the refer-
are a mean of three or more determinations.)
ence compound in a laboratory log. This log record should
Relative Stan-
include the date, the concentration and volume of the reference Standard
Compound Mean RRT dard
Deviation
compound, the operating conditions of the gas chromatograph, Deviation, %
the carrier gas flow rate, the recorder constants, and the degree
Acetone 0.676 0.014 2.1
Amyl acetate 2.156 0.047 2.18
of signal attenuation. It should also include the flow rate of air
Isoamyl acetate 2.228 0.107 4.8
and hydrogen to the detector flame.
Benzene 1.000
8.1.4.11 Prepare 0.05 % solutions (or other concentrations)
Butanol 2.945 0.155 5.3
of organic solvents of interest and develop a set of RTs for
Isobutanol 2.146 0.935 43.6
them. It is preferable to run more than one analysis for each
2-Butanone (MEK) 0.930 0.085 9.14
solvent.
Butyl acetate 1.739 0.026 1.5
Isobutyl acetate 1.37
8.1.4.12 Record both the RT and the detector response. For
Carbon tetrachloride 0.74 0.014 1.9
general analytical usage these data provide a quick means of
ascertaining crude concentration levels. (When precise infor- Cellosolve 5.27
Cellosolve acetate 6.51
mation is necessary, fresh standards are run to prepare a
Chloroform 1.298 0.03 2.3
standard curve.)
Ethanol 1.078 0.001 0.1
Ethyl acetate 0.812 0.027 3.3
8.1.4.13 Using the RT of the reference compound as the
denominator and the RT of the solute as the numerator,
Ethyl benzene 2.183 0.002 0.1
calculate the relative retention time (RRT). This parameter is a
Ethylene chloride 1.408 0.33 23.4
Methyl acetate 0.639 0.015 2.4
constant for a given set of operating conditions. It may be used
Methanol 1.020 0.028 2.7
for rapid and accurate qualitative analysis when there is no
Methylene chloride 0.875 0.005 0.57
reason to believe that there are peak superimpositions. A
Methyl isobutyl ketone 1.382 0.009 0.7
separate laboratory log for RRTs should be developed and
Pentanol 5.11
maintained, using at least two columns of different polarities.
Perchloroethylene 1.335 0.019 1.4
(A list of such values is given in Table 1, for example only.) A Propanol 1.659 0.018 1.1
Isopropanol 1.033 0.0099 1.0
gas chromatograph interfaced with a mass spectrometer pro-
vides the most positive means of peak identification.
Propyl acetate 1.16 0.028 2.4
8.1.4.14 It is good practice to ascertain periodically the Isopropyl acetate 0.828 0.017 2.1
Styrene 4.467 0.270 6.0
relative standard deviation of this parameter for all solutes of
Toluene 1.505 0.016 1.06
interest.
Trichloroethylene 1.162 0.03 2.6
8.1.5 The quantitative response of a GC detector may be
Trimethyl benzene 3.72
determined by the peak height measurement or peak area
1,1,1-Trichloroethane 0.78
integration using an electronic integrator or a data system. A
m-Xylene 2.309 0.107 4.6
o-Xylene 2.964 0.058 1.96
detailed description of these techniques can be found in
p-Xylene 2.315 0.04 1.7
Practice E 355.
8.2 For any compound of interest a set of standards should
be prepared in the eluent to be used for the samples (usually
8.2.4 A fresh set of standards should be prepared for each
CS ). The concentration levels of the standards should be such
2 analytical series. Generally standards kept in properly closed
as to embrace the concentration of the unknown quantity.
vials, sealed with TFE-fluorocarbon lined screw caps, will keep
8.2.1 Prepare at least three standard solutions that bracket
for at least a week if refrigerated (5). Standards kept in
the expected concentration of the analyte in the sample.
containers capped by glass stoppers will not keep lo
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