1、Designation: D 4128 06Standard Guide forIdentification and Quantitation of Organic Compounds inWater by Combined Gas Chromatography and ElectronImpact Mass Spectrometry1This standard is issued under the fixed designation D 4128; the number immediately following the designation indicates the year ofo
2、riginal adoption 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 guide covers the identification and quantitation oforg
3、anic 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 interest canbe i
4、ntroduced 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 chromatography (GC).These
5、 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 D 3871, D 3973, and other GC-MSvolatile/se
6、mivolatile 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 condition of th
7、e 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 estimate (IDE)
8、 and the interlaboratory quantitation esti-mate (IQE), follow Practices D 6091 and D 6512.1.3 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, direct aqueous
9、 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 to address a
10、ll 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:3D 1066 Practice for
11、 Sampling SteamD 1129 Terminology Relating to WaterD 1192 Guide for Equipment for Sampling Water andSteam in Closed Conduits4D 1193 Specification for Reagent WaterD 2908 Practice for Measuring Volatile Organic Matter inWater by Aqueous-Injection Gas ChromatographyD 3370 Practices for Sampling Water
12、from Closed ConduitsD 3694 Practices for Preparation of Sample Containers andfor Preservation of Organic ConstituentsD 3871 Test Method for Purgeable Organic Compounds inWater Using Headspace SamplingD 3973 Test Method for Low-Molecular Weight Haloge-nated Hydrocarbons in WaterD 5175 Test Method for
13、 Organohalide Pesticides and Poly-chlorinated Biphenyls in Water by Microextraction andGas ChromatographyD 5316 Test Method for 1,2-Dibromoethane and 1,2-Dibromo-3-Chloropropane in Water by Microextractionand Gas ChromatographyD 5317 Test Method for Determination of Chlorinated Or-ganic Acid Compoun
14、ds in Water by Gas Chromatographywith an Electron Capture DetectorD 5789 Practice for Writing Quality Control Specifications1This guide is under the jurisdiction of ASTM Committee D19 on Water and isthe direct responsibility of Subcommittee D19.06 on Methods for Analysis forOrganic Substances in Wat
15、erCurrent edition approved July 1, 2006. Published July 2006. Originally publishedas D 4128 82. Last previous edition approved in 2001 as D 4128 01.2U.S. EPA Methods 624 and 8260 (volatiles) and U.S. EPA Methods 625 and8270 (semivolatiles) are suitable for quantitation.3For referenced ASTM standards
16、, 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.4Withdrawn.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshoho
17、cken, PA 19428-2959, United States.for Standard Test Methods for Organic Constituents4D 6091 Practice for 99 %/95 % Interlaboratory DetectionEstimate (IDE) for Analytical Methods with NegligibleCalibration ErrorD 6512 Practice for Interlaboratory Quantitation EstimateE 260 Practice for Packed Column
18、 Gas ChromatographyE 355 Practice for Gas Chromatography Terms and Rela-tionships2.2 U.S. Environmental Protection Agency:SW-846 Method 8270c Semivolatile Organic Compoundsby Gas Chromatography (GC-MS)5,6SW-846 Method 8260b Volatile Organic Compounds byGas Chromatography (GC-MS)5,6Methods for the De
19、termination 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, Au-gust 199053. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 volatile organic compoun
20、dan 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 mustelute from the column within its temperature range withoutalteration of the structure of the compound.3.1.
21、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. The compounds must elute from thecolumn within its temperature range without alteration of thestructure of the
22、 compound.3.1.3 tentative identificationall identifications are consid-ered tentative until confirmed by co-injection of an authenticreference compound showing identical retention time andsimilar mass spectra. (Tentative identification based on librarymatches only are subjected to false positives.)3
23、.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 component as shown by co-injection or standardaddition, and (2) correspondence of the sample component andthe standar
24、d 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 should be assigned by using extracted ioncurrent profiles for ions unique to the component of interest. Tomeet th
25、e 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 sample spectrum; the relative intensities of theseions must agree within6 20 % between the standard andsample s
26、pectra. (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 in the sample mass spectrum causedby co-eluting interfering components that are not present in thereference mas
27、s 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 areference compound as demonstrated by co-injection of theauthentic standard with the tentatively identified compound.
28、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 in the ion beam for each spectrum scan plottedagainst the corresponding spectrum number. Generally, it canbe co
29、rrelated 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, reconstructedion chromatogram, total ion current profile, and total ion chromatogram.3.1.7 reference compoundsthese ar
30、e authentic materialsused to obtain mass spectra, gas chromatographic retentiondata, and response factors. The operator can prepare thestandards or they can be prepared commercially. Qualitycontrol solutions should be prepared independently from thecalibration solutions. Quantitation methods may als
31、o 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 for only those ions having particular mass to chargeratios. It is a means of quickly scanning a complex RGC p
32、lotto 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 current use for mass chromato-gram. These include: mass fragmentogram, extracted ion current profile,and limited ma
33、ss 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 mass chromato-gram of a primary ion, a secondary characteristic ion must beused for quantitation.3.2 Definition
34、s:3.2.1 For definitions of terms relating to water used in thisguide, refer to definitions in D 1129. For definitions of termsrelating to gas chromatography used in this guide, refer toPractice E 355.4. Summary of Practice4.1 The guide consists of the introduction of organic com-pounds from water in
35、to a GC-MS for mass spectral identifica-tion and guidelines to determine concentration. Volatile organiccompounds are typically introduced through a purge-and-trapsample introduction device, although volatile compounds canalso be introduced by direct aqueous injection. Semi-volatilecompounds are typ
36、ically introduced as organic extracts from an5Available from National Technical Information Service (NTIS), 5285 PortRoyal Road, Springfield, VA 22161.6SW 846 can be found online at http:/www.epa.gov/epaoswer/hazwaste/test/main.htm.D 4128 062extracted sample by syringe. A components spectrum isrecor
37、ded 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 tentative identification may be confirmed by co-injection of an authentic standard yielding an identical reten-tion
38、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 specific compounds present and to determine theconcentration.6. Interferences6.1 Sample alteration and losses of the comp
39、onent 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, adsorption,and both volatilization prior to introduction into the GC andnon-volatilization after introduction into the G
40、C. 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 can interfere with this guide. These interferences canchange the apparent mass spectrum of the compound ofinteres
41、t, thereby making tentative identification difficult.6.3 Other interferences, such as background GC peaks dueto contaminated sample preparation reagent blanks, GC col-umns, instrumentation or column bleed, are common problemsthat the analyst must strive to understand and eliminate.6.4 Isomeric compo
42、unds 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 actual incorrect identification in some cases.The analyst must be aware of this potential problem.6.5 When attempting t
43、o identify compounds in watersamples containing large numbers of compounds, particularlycomplex mixtures such as petroleum products, great care mustbe exercised to determine that candidate unknown mass spectraare free of interfering peaks as possible. Judicious background-subtraction can assist in t
44、his endeavor. Additional informationcan be gathered by examining the extracted ion current profilesof the major mass spectral peaks in the candidate spectrum.Frequently, the occurrence of contaminated spectra can bedetermined by noting differences in the profiles of several masschromatograms that do
45、 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 from complex samples, and the analyst must beaware of this in interpreting unknowns against referencespectra.7. Appar
46、atus7.1 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 system for computerized instrument control of dataacquisition and data reduction. Capillary columns are preferredwith
47、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 apparatus includes a 2-L separatory funnel forbatch extractions or 1-L continuous liquid-liquid extractor andfacilities
48、for Kuderna-Danish concentration. Liquid-liquid ex-traction for volatile organic constituents can be conductedusing the apparatus specified in Test Method D 3973.7.3 Apparatus for purge-and-trap GC-MS sampleintroductionSee Test Method D 3871 or EPA Method 524.2.7.4 Microsyringe, 10-L.8. Reagents and
49、 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 of interfering impurities.9In all cases,sufficient reagent blanks must be processed with the samples toensure that a
