1、Designation: D4128 06 (Reapproved 2012)Standard Guide forIdentification and Quantitation of Organic Compounds inWater by Combined Gas Chromatography and ElectronImpact Mass Spectrometry1This standard is issued under the fixed designation D4128; the number immediately following the designation indica
2、tes the year oforiginal adoption 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 guide covers the identification and qua
3、ntitation oforganic compounds by gas chromatography/mass spectrometry(GC-MS) (electron impact) that are present or extracted fromwater and are capable of passing through a gas chromatographwithout alteration. The guide is intended primarily for solu-tions for which 1 ng or more of any component of i
4、nterest canbe introduced onto a gas chromatographic column. This guidehas the advantage of providing tentative identifications ofvolatile and semi-volatile organics, but is restricted to (a)compounds for which reference spectra can be obtained and (b)compounds that can be separated by gas chromatogr
5、aphy (GC).These restrictions are imposed on the guide, but are not alimitation of the technique. The guide is written for, but notrestricted to, analysis using automated data acquisition andhandling.1.2 Guidelines have been included for quantitation usingASTM Test Methods D3871, D3973, and other GC-
6、MSvolatile/semivolatile procedures used for environmental analy-sis2. A detection amount of 1 ng can only be consideredapproximate. The actual detection limits for each componentmust be determined in each laboratory. Actual detectionamounts will vary with the complexity of the matrix, the kindand co
7、ndition of the GC-MS system, the sample preparationtechnique chosen, and the application of cleanup techniques tothe sample extract, if any. Lower levels of detection can beachieved using modern sensitive instruments or with selectedion monitoring (SIM). To determine the interlaboratory detec-tion e
8、stimate (IDE) and the interlaboratory quantitation esti-mate (IQE), follow Practices D6091 and D6512.1.3 The guide is applicable to the identification of manyorganic constituents of natural and treated waters. It includesall modes of sample introduction, including injection of or-ganic extracts, dir
9、ect aqueous injection, and purge and traptechniques.1.4 The guide is applicable to either packed or capillarycolumn gas chromatography, including wide-bore capillarycolumns. Because of their greatly enhanced resolution, capil-lary columns are strongly recommended.1.5 This standard does not purport t
10、o 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 to use.2. Referenced Documents2.1 ASTM Standards:3D1066 Pr
11、actice for Sampling SteamD1129 Terminology Relating to WaterD1192 Guide for Equipment for Sampling Water and Steamin Closed Conduits4D1193 Specification for Reagent WaterD2908 Practice for Measuring Volatile Organic Matter inWater by Aqueous-Injection Gas ChromatographyD3370 Practices for Sampling W
12、ater from Closed ConduitsD3694 Practices for Preparation of Sample Containers andfor Preservation of Organic ConstituentsD3871 Test Method for Purgeable Organic Compounds inWater Using Headspace SamplingD3973 Test Method for Low-Molecular Weight Haloge-nated Hydrocarbons in WaterD5175 Test Method fo
13、r Organohalide Pesticides and Poly-chlorinated Biphenyls in Water by Microextraction andGas ChromatographyD5316 Test Method for 1,2-Dibromoethane and 1,2-Dibromo-3-Chloropropane in Water by Microextraction1This guide is under the jurisdiction of ASTM Committee D19 on Water and isthe direct responsib
14、ility of Subcommittee D19.06 on Methods for Analysis forOrganic Substances in WaterCurrent edition approved June 15, 2012. Published August 2012. Originallypublished as D4128 82. Last previous edition approved in 2006 as D4128 06.DOI: 10.1520/D4128-06R12.2U.S. EPA Methods 624 and 8260 (volatiles) an
15、d U.S. EPA Methods 625 and8270 (semivolatiles) are suitable for quantitation.3For 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 ont
16、he ASTM website.4Withdrawn. The last approved version of this historical standard is referencedon www.astm.org.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.and Gas ChromatographyD5317 Test Method for Determination of Chlorinated O
17、r-ganic Acid Compounds in Water by Gas Chromatographywith an Electron Capture DetectorD5789 Practice for Writing Quality Control Specificationsfor Standard Test Methods for Organic Constituents4D6091 Practice for 99a?%/95a?% Interlaboratory Detec-tion Estimate (IDE) for Analytical Methods with Negli
18、-gible Calibration ErrorD6512 Practice for Interlaboratory Quantitation EstimateE260 Practice for Packed Column Gas ChromatographyE355 Practice for Gas Chromatography Terms and Rela-tionships2.2 U.S. Environmental Protection Agency:SW-846 Method 8270c Semivolatile Organic Compoundsby Gas Chromatogra
19、phy (GC-MS)5,6SW-846 Method 8260b Volatile Organic Compounds byGas Chromatography (GC-MS)5,6Methods for the Determination of Organic Compounds inDrinking Water-Supplement I, EPA/600/4-90/020, July19905Methods for the Determination of Organic Compounds inDrinking Water-Supplement II, EPA/600/R-92/129
20、, Au-gust 199053. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 volatile organic compoundan organic compoundthat can be readily separated from water by inert gas spargingand thermally desorbed onto a GC column or is readilyamenable to direct aqueous injection GC. The compounds
21、mustelute from the column within its temperature range withoutalteration of the structure of the compound.3.1.2 semi-volatile organic compoundan organic com-pound that can be separated from water by extraction, eitherliquid/liquid or solid phase, undergo volume adjustment, andbe injected onto a GC.
22、The compounds must elute from thecolumn within its temperature range without alteration of thestructure of the compound.3.1.3 tentative identificationall identifications are consid-ered tentative until confirmed by co-injection of an authenticreference compound showing identical retention time andsi
23、milar mass spectra. (Tentative identification based on librarymatches only are subjected to false positives.)3.1.4 matchtwo criteria must be satisfied to verify acomparison of a sample component to a standard match: (1)elution of the sample component at the same retention time asthe standard compone
24、nt as shown by co-injection or standardaddition, and (2) correspondence of the sample component andthe standard component mass spectrum. If co-elution of inter-fering components prohibits accurate assignment of the samplecomponent retention time from the total ion chromatogram, theretention time sho
25、uld be assigned by using extracted ioncurrent profiles for ions unique to the component of interest. Tomeet the second criteria, all ions present in the authentic massspectra at a relative intensity greater than 10 % (whereas themost abundant ion in the spectrum equals 100 %) must bepresent in the s
26、ample spectrum; the relative intensities of theseions must agree within6 20 % between the standard andsample spectra. (As an example, for an ion with an abundanceof 50 % in the standard spectra, the corresponding sampleabundance must be between 30 % and 70 %.) However, theremay be additional peaks i
27、n the sample mass spectrum causedby co-eluting interfering components that are not present in thereference mass spectrum.3.1.5 confirmed identificationin order to confirm a tenta-tive identification, both the GC retention time and the massspectrum of a compound shall uniquely match those of areferen
28、ce compound as demonstrated by co-injection of theauthentic standard with the tentatively identified compound.3.1.6 reconstructed gas chromatogram (see Note 1)(RGC)an RGC is the computer output representing either thesummed intensities of all scanned ion intensities or a sample ofthe total current i
29、n the ion beam for each spectrum scan plottedagainst the corresponding spectrum number. Generally, it canbe correlated with a flame ionization detector gas chromato-gram.NOTE 1There are many synonyms in common use for RGC. Theseinclude: total ionization plot, total ionization current trace, reconstr
30、uctedion chromatogram, total ion current profile, and total ion chromatogram.3.1.7 reference compoundsthese are authentic materialsused to obtain mass spectra, gas chromatographic retentiondata, and response factors. The operator can prepare thestandards or they can be prepared commercially. Quality
31、control solutions should be prepared independently from thecalibration solutions. Quantitation methods may also requiresurrogate spiking solutions to determine extraction efficiency.3.1.8 mass chromatogram (see Note 2)a limited massRGC, or mass chromatogram, represents the intensities of ioncurrents
32、 for only those ions having particular mass to chargeratios. It is a means of quickly scanning a complex RGC plotto locate peaks which could be specific compounds or types ofcompounds. However, a complete mass spectrum is requiredfor tentative identification.NOTE 2There are several synonyms in curre
33、nt use for mass chromato-gram. These include: mass fragmentogram, extracted ion current profile,and limited mass reconstructed gas chromatogram.3.1.9 characteristic ionusually the primary ion in themass spectrum used to measure response for quantitationpurposes. When there are interferences in the m
34、ass chromato-gram of a primary ion, a secondary characteristic ion must beused for quantitation.3.2 Definitions:3.2.1 For definitions of terms relating to water used in thisguide, refer to definitions in D1129. For definitions of termsrelating to gas chromatography used in this guide, refer toPracti
35、ce E355.4. Summary of Practice4.1 The guide consists of the introduction of organic com-pounds from water into a GC-MS for mass spectral identifica-tion and guidelines to determine concentration. Volatile organic5Available from National Technical Information Service (NTIS), 5285 PortRoyal Road, Spri
36、ngfield, VA 22161.6SW 846 can be found online at http:/www.epa.gov/epaoswer/hazwaste/test/main.htm.D4128 06 (2012)2compounds are typically introduced through a purge-and-trapsample introduction device, although volatile compounds canalso be introduced by direct aqueous injection. Semi-volatilecompou
37、nds are typically introduced as organic extracts from anextracted sample by syringe. A components spectrum isrecorded as the component elutes from the chromatographiccolumn. The tentative identification of a sample component isbased on its mass spectrum and supported by its GC retentiondata. This te
38、ntative identification may be confirmed by co-injection of an authentic standard yielding an identical reten-tion time and a similar mass spectrum.5. Significance and Use5.1 With the common occurrence in water of organiccompounds, some of which are toxic, it is often necessary toidentify the specifi
39、c compounds present and to determine theconcentration.6. Interferences6.1 Sample alteration and losses of the component ofinterest are not true interferences, but are a source of trouble inperforming a qualitative GC-MS analysis. Examples of com-ponent loss are: decomposition, polymerization, adsorp
40、tion,and both volatilization prior to introduction into the GC andnon-volatilization after introduction into the GC. In addition,GC-MS interface plugging can lead to apparent losses.6.2 Chromatographically unresolved compounds or instru-mental background which co-elutes with the compounds ofinterest
41、 can interfere with this guide. These interferences canchange the apparent mass spectrum of the compound ofinterest, thereby making tentative identification difficult.6.3 Other interferences, such as background GC peaks dueto contaminated sample preparation reagent blanks, GC col-umns, instrumentati
42、on or column bleed, are common problemsthat the analyst must strive to understand and eliminate.6.4 Isomeric compounds may be difficult to separate by GCand the mass spectra of isomers are frequently identical withinexperimental error. This could lead to either ambiguity inidentification or to actua
43、l incorrect identification in some cases.The analyst must be aware of this potential problem.6.5 When attempting to identify compounds in watersamples containing large numbers of compounds, particularlycomplex mixtures such as petroleum products, great care mustbe exercised to determine that candida
44、te unknown mass spectraare free of interfering peaks as possible. Judicious background-subtraction can assist in this endeavor. Additional informationcan be gathered by examining the extracted ion current profilesof the major mass spectral peaks in the candidate spectrum.Frequently, the occurrence o
45、f contaminated spectra can bedetermined by noting differences in the profiles of several masschromatograms that do not exactly fit the profiles of the peaksof the compound of interest. These may be co-eluting interfer-ences. However, it is rarely possible to completely eliminate allinterferences fro
46、m complex samples, and the analyst must beaware of this in interpreting unknowns against referencespectra.7. Apparatus7.1 GC-MS/DSA gas chromatograph interfaced to a massspectrometer having electron impact ionization capability isused.7Most modern GC-MS systems are typically controlledby a data syst
47、em for computerized instrument control of dataacquisition and data reduction. Capillary columns are preferredwith most GC-MS systems although packed GC columns maybe used.7.2 Apparatus required to extract organic compounds fromwater and concentrate them in a small volume of organicsolventThis appara
48、tus includes a 2-L separatory funnel forbatch extractions or 1-L continuous liquid-liquid extractor andfacilities for Kuderna-Danish concentration. Liquid-liquid ex-traction for volatile organic constituents can be conductedusing the apparatus specified in Test Method D3973.7.3 Apparatus for purge-a
49、nd-trap GC-MS sampleintroductionSee Test Method D3871 or EPA Method 524.2.7.4 Microsyringe, 10-L.8. Reagents and Materials8.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the specifications of the Commit-tee onAnalytical Reagents of theAmerican Chemical Society.8For trace analysis using organic solvents for liquid-liquidextraction or elution from solid sorbents, solvents specified asdistilled-in-glass, nano-grade, or pesticide-grade frequentlyhave lower levels o
