1、Designation: D5241 92 (Reapproved 2017)Standard Practice forMicro-Extraction of Water for Analysis of Volatile and Semi-Volatile Organic Compounds in Water1This standard is issued under the fixed designation D5241; the number immediately following the designation indicates the year oforiginal adopti
2、on or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers standard procedures for extractionof volatile and sem
3、i-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 asolve
4、nt 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 regar
5、ded asstandard. No other units of measurement are included in thisstandard.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, health, and environmental practi
6、ces and deter-mine the applicability of regulatory limitations prior to use.For specific hazard statements, see Section 91.7 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelo
7、pment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D1129 Terminology Relating to WaterD1193 Specification for Reagent WaterD3370 Practices for Sampling Water from C
8、losed ConduitsD3694 Practices for Preparation of Sample Containers andfor Preservation of Organic ConstituentsD3856 Guide for Management Systems in LaboratoriesEngaged in Analysis of WaterD3973 Test Method for Low-Molecular Weight HalogenatedHydrocarbons in WaterD4210 Practice for Intralaboratory Qu
9、ality Control Proce-dures and a Discussion on Reporting Low-Level Data(Withdrawn 2002)3D4448 Guide for Sampling Ground-Water Monitoring WellsD5175 Test Method for Organohalide Pesticides and Poly-chlorinated Biphenyls in Water by Microextraction andGas Chromatography3. Summary of Practice3.1 This pr
10、actice employs liquid/liquid extraction to isolatecompounds of 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
11、and salt may be added prior to extraction to increasethe extraction 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 semivolatil
12、e organic compounds. Thispractice does not include sample extract 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 th
13、e solvent extraction of organic constituents forthe purpose of 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 detector1This practice is und
14、er the jurisdiction of ASTM Committee D19 on Water andis the direct responsibility of Subcommittee D19.06 on Methods for Analysis forOrganic Substances in Water.Current edition approved Dec. 15, 2017. Published January 2018. Originallyapproved in 1992. Last previous edition approved in 2011 as D5241
15、 92 (2011).DOI: 10.1520/D5241-92R17.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3The last approved versio
16、n of this historical standard is referenced onwww.astm.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization establishe
17、d in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1(ECD), or with a mass spectrometer (GC/MS) range frommilligrams per litre (mg/L) to nanograms per litre (ng/L)
18、. 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.4.3 Micro-extraction has th
19、e advantage of speed, simpleextraction devices, and the use of small amounts of sample andsolvents.4.3.1 Selectivity can be improved by the choice of solvent(usually hexane or pentane) or mixed solvents, extraction timeand temperature, and ionic strength of the solution.4.3.2 Extraction devices can
20、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 bedetermined by this practice includes both high and low boilingcompounds or chemicals (see Table 1).5. Interferences5.1 Solve
21、nts, reagents, glassware, and other sample process-ing hardware may yield discrete artifacts or elevated baselinesthat can cause poor precision and accuracy. See TerminologyD1129.5.1.1 Glassware should be washed with detergent, rinsedwith water, followed by a rinse with distilled in glass acetone.Fi
22、nal 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 beencleaned, it should be used immediately or stored wrapped inaluminum foil (shiny side out) or by stretching a sheet ofPTFE-flu
23、orocarbon 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 field blank prepared from water and carried throughsampling, subsequent storage, and handling can serve as acheck on sour
24、ces of interferences from the containers.5.2 When performing analyses for specific organiccompounds, matrix interferences may be caused by materialsand constituents that are coextracted from the sample. Theextent of such matrix interferences will vary considerablydepending on the sample and the spec
25、ific instrumental analysismethod used. Matrix interferences may be reduced by thechoice of extracting solvent, or by using a clean-up techniqueon the extract.6. Selection of the Extraction Solvent6.1 The selection of solvent for extraction will depend uponmany factors, including the following:6.1.1
26、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 beenfound to be critical to achieve optimum recovery of someanalytes (see Test Method D3973). Typical solvent to sampleratios ar
27、e 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 point and viscosity of the solvent,6.1.5 The tendency of the solvent and matrix to formemulsions, and6.1.6 Solubility of the solve
28、nt 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 applying thisprocedure for sample analysis.7. Apparatus7.1 Volumetric Flasks, 110 mL.47.2 Liquid/Liquid Extractor.57.3 Vials, au
29、to 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 Bottles, glass narrow mouth with TFE fluorocarbon-lined septum screw caps.7.6 Shaker, wrist.8. Reagents8.1 Purity of WaterUnle
30、ss otherwise indicated, referenceto water shall be understood to mean reagent water conformingto Type II of Specification D1193.4Cassia, available from Baxter, 1430 Waukegan Rd., McGaw Park, IL 60085, orequivalent, has been found suitable for this purpose.5Available from J & W Scientific, 91 Blue Ra
31、vine Rd., Folsom, CA 95630, orequivalent, has been found suitable for this purpose.TABLE 1 Results of Flame Ionization Detector (FID) and ElectronCapture Detector (ECD) DetectabilityANOTE 1Lowest levels tested.FID (g/L) ECD (ng/L)Trichloroethene 2 5Tetrachloroethene 2 5Monochlorobenzene 1 500para-Ch
32、lorobenzotrifluoride 1 5ortho-Chlorobenzotrifluoride 1 5ortho-Chlorotoluene 1 100meta-Chlorotoluene 1 100para-Chlorotoluene 1 1001,2,4-Trichlorobenzene 1 51,2,3-Trichlorobenzene 1 5Hexachlorobutadiene 1 51,2,4,5-Tetrachlorobenzene 1 5Hexachlorocyclopentadiene 2 52,4,5-Trichlorophenol 2 1001,2,3,4-Te
33、trachlorobenzene 1 5alpha-Hexachlorocyclohexane 1 5beta-Hexachlorocyclohexane 1 5Hexachlorobenzene 1 5gamma-Hexachlorocyclohexane 1 5delta-Hexachlorocyclohexane 1 5ABased on the injection of chlorinated compounds in pentane solution, taking intoconsideration the 100:1 concentration of a water sample
34、 by the microextractiontechnique.D5241 92 (2017)28.2 Chromatographic grade solvents that have 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 the
35、determination.8.3 The extraction solvent of choice should be appropriatefor the matrix and compounds 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 r
36、eagent or ACS grade or better. When they are not availableas reagent grade, they should have 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 d
37、is-solving 40 g NaOH in water and diluting to 100 mL.8.7 Sodium Sulfate (Na2SO4), reagent grade, granular,anhydrous, prepared by heating to 300C under a flow ofnitrogen.NOTE 1Nitrogen is only required when trace work using ECD isrequired.8.8 Magnesium Sulfate (MgSO4), reagent grade, granular,anhydro
38、us, prepared by heating at 400C for a minimum of 4h in a shallow tray to eliminate interfering organics.8.9 Sodium Chloride (NaCl), reagent grade, granular.8.10 Sodium Thiosulfate(Na2S2O3), reagent grade, granu-lar.9. Hazards9.1 The toxicity and carcinogenicity of chemicals used orthat could be used
39、 in this practice have not been preciselydefined. Each chemical should be treated as a potential healthhazard. Exposure to these chemicals should be minimized.Each laboratory is responsible for maintaining awareness ofOSHA regulations regarding safe handling of chemicals usedin this practice.9.2 If
40、using ether solvents, the hazard of peroxides forma-tion should be considered by testing for the presence ofperoxide prior to use.10. Sample Handling10.1 There are many procedures for acquiring representa-tive samples of water. The procedure chosen will be site andanalysis specific. There are severa
41、l guides and practices forsampling listed in the ASTM subject index under Sampling-Water Applications. Two good sources are Practices D3370and Guide D4448.10.2 The recommended sample size is 40 to 100 mL. Moreor less sample can be used depending upon the sampleavailability, detection limits required
42、, and the expected con-centration level of the analyte. Forty millilitre VOA vials arecommonly used as sampling containers. Head space should beeliminated if volatiles analysis is required.10.3 Sample Storage:10.3.1 All samples must be iced or refrigerated to 4C fromthe time of collection until read
43、y for extraction.10.3.2 Samples should be stored in a clean dry place awayfrom samples containing high concentrations of organics.10.4 Sample Preservation:10.4.1 Some compounds are susceptible to rapid biologicaldegradation under certain environmental conditions. If biologi-cal activity is expected,
44、 adjust the pH of the sample to about 2by adding HCl. The constituent of concern must be stableunder acid conditions. For additional information, see PracticesD3694.10.4.2 If residual chlorine is present, add sodium thiosulfateas a preservative (30 mg/4 oz bottle).NOTE 2Any reagents added to the sam
45、ple at the time of collection orbefore analysis must be added to the laboratory blank and standard. See11.3.11. Quality Control11.1 Minimum quality control requirements are an initialdemonstration of laboratory capability, analysis of methodblanks, a laboratory fortified blank, a laboratory fortifie
46、dsample matrix and, if available, quality control samples. For ageneral discussion of good laboratory practices, see GuideD3856 and Practice D4210.11.2 Select a representative spike concentration (about threetimes the estimated detection limit or expected concentration)for each analyte. Extract acco
47、rding to Section 12 and analyze.11.3 Method blanks must be prepared using reagent gradewater and contain all the reagents used in sample preservationand preparation. The blanks must be carried through the entireanalytical procedure with the samples. Each time a group ofsamples are run that contain d
48、ifferent reagents or reagentconcentrations, a new method blank must be run.11.4 All calibration and quality control standards must beextracted using the same reagents, procedures, and conditionsas the samples.11.5 Precision and bias must be established for each matrixand laboratory analytical method
49、.11.5.1 Precision should be determined by splitting spikedsamples or analytes in the batch into two equal portions. Thereplicate samples should then be extracted and analyzed.11.5.2 Bias should be determined in the laboratory byspiking the samples with the analytes of interest at a concen-tration three times the concentration found in the samples orless.NOTE 3The bias may be decreased by keeping the temperature,shaking speed and time, ionic strength, and solvent and sample volumesconstant.12. Procedure12.1 Remove samples from storage and allow them toequilibrat
