1、Designation: D 5241 92 (Reapproved 2004)Standard Practice forMicro-Extraction of Water for Analysis of Volatile and Semi-Volatile Organic Compounds in Water1This standard is issued under the fixed designation D 5241; the number immediately following the designation indicates the year oforiginal adop
2、tion or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers standard procedures for extractionof volatile and
3、semi-volatile organic compounds from waterusing small volumes of solvents.1.2 The compounds of interest must have a greater solubil-ity in the organic solvent than the water phase.1.3 Not all of the solvents that can be used in microextraction are addressed in this practice. The applicability of aso
4、lvent to extract the compound(s) of interest must be demon-strated before use.1.4 This practice provides sample extracts suitable for anytechnique amenable to solvent injection such as gas chroma-tography or high performance liquid chromatography (HPLC).1.5 The values stated in SI units are to be re
5、garded as thestandard.1.6 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior
6、to use. For specific hazardstatements, see Section 9.2. Referenced Documents2.1 ASTM Standards:2D 1129 Terminology Relating to WaterD 1193 Specification for Reagent WaterD 3370 Practices for Sampling Water from Closed ConduitsD 3694 Practices for Preparation of Sample Containers andfor Preservation
7、of Organic ConstituentsD 3856 Guide for Good Laboratory Practice in LaboratoriesEngaged in Sampling and Analysis of Water and Waste-waterD 3973 Test Method for Low-Molecular Weight Haloge-nated Hydrocarbons in WaterD 4210 Practice for Intralaboratory Quality Control Proce-dures and a Discussion on R
8、eporting Low-Level Data3D 4448 Guide for Sampling Groundwater Monitoring WellsD 5175 Test Method for Organohalide Pesticides and Poly-chlorinated Biphenyls in Water by Microextraction andGas Chromatography3. Summary of Practice3.1 This practice employs liquid/liquid extraction to isolatecompounds of
9、 interest. The sample is added to an extractiondevice. The solvent may be added to the sample container or anextraction device and extracted for a period of 5 min. Thesolvent is then ready for analysis. If required, the pH may beadjusted and salt may be added prior to extraction to increasethe extra
10、ction specificity and efficiency.3.2 The solvent extract may be further processed usingsample clean-up and concentration techniques. The analytes inthe solvent may be analyzed using instrumental methods forspecific volatile or semivolatile organic compounds. Thispractice does not include sample extr
11、act clean-up methods.4. Significance and Use4.1 This practice provides a general procedure for thesolvent extraction of volatile and semi-volatile organic com-pounds from a water matrix. Solvent extraction is used as theinitial step in the solvent extraction of organic constituents forthe purpose of
12、 quantifying extractable organic compounds.4.2 Typical detection limits that can be achieved usingmicro-extraction techniques with gas chromatography (GC)with flame ionization detector (FID), electron capture detector(ECD), or with a mass spectrometer (GC/MS) range frommilligrams per litre (mg/L) to
13、 nanograms per litre (ng/L). Thedetection limit, linear concentration range, and sensitivity ofthe test method for a specific organic compound will dependupon the sample clean-up, injection volume, solvent to sampleratio, solvent concentration methods used, and the determina-tive technique employed.
14、4.3 Micro-extraction has the advantage of speed, simpleextraction devices, and the use of small amounts of sample andsolvents.1This practice is under the jurisdiction of ASTM Committee D19 on Water andis the direct responsibility of Subcommittee D19.06 on Methods for Analysis forOrganic Substances i
15、n Water.Current edition approved June 1, 2004. Published June 2004. Originallyapproved in 1992. Last previous edition approved in 1998 as D 5241 92 (1998).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTM
16、Standards volume information, refer to the standards Document Summary page onthe ASTM website.3Withdrawn1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4.3.1 Selectivity can be improved by the choice of solvent(usually hexane or pent
17、ane) or mixed solvents, extraction timeand temperature, and ionic strength of the solution.4.3.2 Extraction devices can vary from the sample containeritself to commercial devices specifically designed for micro-extraction. See 7.1 and 7.2.4.3.3 A list of chlorinated organic compounds that can bedete
18、rmined by this practice includes both high and low boilingcompounds or chemicals (see Table 1).5. Interferences5.1 Solvents, reagents, glassware, and other sample process-ing hardware may yield discrete artifacts or elevated baselinesthat can cause poor precision and accuracy. See TerminologyD 1129.
19、5.1.1 Glassware should be washed with detergent, rinsedwith water, followed by a rinse with distilled in glass acetone.Final drying is done by air or 103C oven. Additional cleaningsteps may be required when the analysis requires levels ofmicrograms per litre or below. Once the glassware has beenclea
20、ned, it should be used immediately or stored wrapped inaluminum foil (shiny side out) or by stretching a sheet ofPTFE-fluorocarbon over the top for storage.5.1.2 Plastics other than PTFE-fluorocarbon should beavoided. They are a significant source of interference and canadsorb some organics.5.1.3 A
21、field blank prepared from water and carried throughsampling, subsequent storage, and handling can serve as acheck on sources of interferences from the containers.5.2 When performing analyses for specific organic com-pounds, matrix interferences may be caused by materials andconstituents that are coe
22、xtracted from the sample. The extent ofsuch matrix interferences will vary considerably depending onthe sample and the specific instrumental analysis method used.Matrix interferences may be reduced by the choice of extract-ing solvent, or by using a clean-up technique on the extract.6. Selection of
23、the Extraction Solvent6.1 The selection of solvent for extraction will depend uponmany factors, including the following:6.1.1 Solvent compatibility with analytical instrumentation,6.1.2 Solubility of the organic constituent in the solventversus its solubility in water. The water/solvent ratio has be
24、enfound to be critical to achieve optimum recovery of someanalytes (see Test Method D 3973). Typical solvent to sampleratios are 1 to 10 or 20. The ratio should be optimized formaximum recovery or detection of an analyte, or both,6.1.3 The availability and purity of the solvent,6.1.4 The boiling poi
25、nt and viscosity of the solvent,6.1.5 The tendency of the solvent and matrix to formemulsions, and6.1.6 Solubility of the solvent in the water.6.2 The analyst should analyze sample blank using thepotential solvent and demonstrate a recovery using a spikingprocedure in the matrix of interest before a
26、pplying thisprocedure for sample analysis.7. Apparatus7.1 Volumetric Flasks, 110 mL.47.2 Liquid/Liquid Extractor.57.3 Vials, auto sampler with septa and caps. Vials should becompatible with the automatic sample injector and should havean internal volume of not greater than 2 mL.7.4 Vial, crimper.7.5
27、 Bottles, glass narrow mouth with TFE fluorocarbon-lined septum screw caps.7.6 Shaker, wrist.8. Reagents8.1 Purity of WaterUnless otherwise indicated, referenceto water shall be understood to mean reagent water conformingto Type II of Specification D 1193.8.2 Chromatographic grade solvents that have
28、 been distilledin glass should be used in all tests. Other grades may be used,if it is first ascertained that the solvent is of sufficiently highpurity to permit its use without lessening the accuracy of thedetermination.8.3 The extraction solvent of choice should be appropriatefor the matrix and co
29、mpounds of interest. This choice isdependent upon the chemical properties of the organic con-stituents of interest and the matrix being extracted.8.4 The spiking, standard materials and surrogates shouldbe reagent or ACS grade or better. When they are not availableas reagent grade, they should have
30、an assay of 90 % or better.8.5 Hydrochloric Acid (HCl) or Sulfuric Acid Solution(H2SO4) (1:1 v:v), prepared by slowly adding 50 mL of acid to50 mL of water.8.6 Sodium Hydroxide Solution (NaOH), prepared by dis-solving 40 g NaOH in water and diluting to 100 mL.4Cassia, available from Baxter, 1430 Wau
31、kegan Rd., McGaw Park, IL 60085, orequivalent, has been found suitable for this purpose.5Available from J be careful not to include any of the waterphase. Preserve this second vial at 4C for an immediatereanalysis if necessary.12.7 If further extraction is required under different pHconditions (acid
32、 neutral or base), carefully remove the remain-ing solvent from the sample, adjust the pH, and add thenecessary fresh solvent volume. Repeat 12.4 and 12.5.12.8 Discard the contents of the sample bottle in an envi-ronmentally safe manner. Shake off the remaining few dropsusing short, brisk wrist move
33、ments, replace the cap, and weighthe empty bottle to the nearest 0.1 g.12.9 Analyze the extracts by the appropriate method(s) andcorrect the results for volume according to Section 13.13. Calculation13.1 Calculate the sample volume (Vs) in mL as equal to thenet sample weight in grams as follows:Vs5
34、grossweight 11.2! 2 tare weight 11.7!NOTE 6Brine samples will require a correction for density if highaccuracy is required. Samples with a high sediment content should becalculated based on weight to weight.13.2 Calculate the corrected sample concentration as fol-lows:13.2.1 When uncorrected analyte
35、 concentration is known:C 5 CiX 1000Vswhere:C = concentration in g/L,Ci= uncorrected analyte concentration in g/mL, andVs= volume of the sample in mL.13.2.2 When only areas or peak heights are known:C 5 Sc3ArSr3ExVs3 1000where:C = concentration, in g/L,Sc= concentration of analyte in the standard, i
36、n g/mL,Ar= response in area or peak height of the analyte in thesample,Sr= response in area or peak height of the standard for theanalyte to be determined,Ex= mL of extract, andVs= volume of sample extracted, in mL.14. Precision and Bias14.1 Precision and bias cannot be determined directly forthis p
37、ractice. However, this procedure was used in the deter-mination of organohalide pesticides, polychlorinated biphe-nyls, and chlorinated organics. See Test Method D 5175.14.2 Precision and bias should be generated in the labora-tory on the parameters of concern.14.3 Precision may be improved by the u
38、se of an internalstandard. Where internal standards are utilized, add the internalstandard to the extraction solvent container prior to aliquotingthe solvent to the extraction vessel.NOTE 7The results of one laboratory determining chlorinated organ-ics listed in Tables 1-3 are being included as info
39、rmation. A Cassiavolumetric flask containing 100 mLof acidified sample was extracted with1 mL of pentane solvent and analyzed using a gas chromatograph withflame ionization and electron capture detectors. The injection volume was1 L. Note that the bias information determined from the data will begre
40、ater than would be expected from this practice. The standard was notprocessed through the entire practice, which would minimize the bias ofthe practice.15. Keywords15.1 extraction; microextraction; sample preparation; semi-volatile; volatile; waterTABLE 2 Recovery Data for Pentane Microextraction of
41、 10 g/LSpiked Field SamplesNOTEBased on the Extraction of Six Spiked Water SolutionsAverage %Recovery% RelativeStandardDeviationTrichloroethene 69 4Tetrachloroethene 72 4Monochlorobenzene 82 3para-Chlorobenzotrifluoride 68 4ortho-Chlorobenzotrifluoride 76 4ortho-Chlorotoluene 88 4meta-Chlorotoluene
42、88 4para-Chlorotoluene 88 41,2,4-Trichlorobenzene 91 41,2,3-Trichlorobenzene 95 4Hexachlorobutadiene 78 41,2,4,5-Tetrachlorobenzene 94 4Hexachlorocyclopentadiene 84 42,4,5-Trichlorophenol 65 91,2,3,4-Tetrachlorobenzene 92 4alpha-Hexachlorocyclohexane 94 5beta-Hexachlorocyclohexane 87 5Hexachlorobenz
43、ene 94 6gamma-Hexachlorocyclohexane 96 4delta-Hexachlorocyclohexane 91 5D 5241 92 (2004)4ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination o
44、f the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn.
45、 Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comm
46、ents have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or
47、multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).TABLE 3 Summary of Recovery Data for the PentaneMicroextraction of Spiked Field SamplesAAver
48、age %Recovery% RelativeStandardDeviationTrichloroethene 71 6Tetrachloroethene 68 4Monochlorobenzene 85 3para-Chlorobenzotrifluoride 63 5ortho-Chlorobenzotrifluoride 74 2ortho-Chlorotoluene 88 2meta-Chlorotoluene 90 4para-Chlorotoluene 89 21,2,4-Trichlorobenzene 89 51,2,3-Trichlorobenzene 93 5Hexachl
49、orobutadiene 64 161,2,4,5-Tetrachlorobenzene 93 4Hexachlorocyclopentadiene 75 102,4,5-Trichlorophenol 60 61,2,3,4-Tetrachlorobenzene 91 5alpha-Hexachlorocyclohexane 95 2beta-Hexachlorocyclohexane 86 2Hexachlorobenzene 95 2gamma-Hexachlorocyclohexane 97 2delta-Hexachlorocyclohexane 90 3AAverage of five replicate spiked water solutions each at 20, 50, and 100 g/Land six replicate spiked water solutions at 10 g/L.D 5241 92 (2004)5
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