ASTM D2908-1991(2011) Standard Practice for Measuring Volatile Organic Matter in Water by Aqueous-Injection Gas Chromatography《用水喷射气体色层分离法测量水中的挥发性有机物质的标准操作规程》.pdf
《ASTM D2908-1991(2011) Standard Practice for Measuring Volatile Organic Matter in Water by Aqueous-Injection Gas Chromatography《用水喷射气体色层分离法测量水中的挥发性有机物质的标准操作规程》.pdf》由会员分享,可在线阅读,更多相关《ASTM D2908-1991(2011) Standard Practice for Measuring Volatile Organic Matter in Water by Aqueous-Injection Gas Chromatography《用水喷射气体色层分离法测量水中的挥发性有机物质的标准操作规程》.pdf(7页珍藏版)》请在麦多课文档分享上搜索。
1、Designation: D2908 91 (Reapproved 2011)Standard Practice forMeasuring Volatile Organic Matter in Water by Aqueous-Injection Gas Chromatography1This standard is issued under the fixed designation D2908; the number immediately following the designation indicates the year oforiginal adoption or, in the
2、 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 general guidance applicable tocertain test methods for the qualita
3、tive and quantitative deter-mination of specific organic compounds, or classes of com-pounds, in water by direct aqueous injection gas chromatogra-phy (1, 2, 3, 4).21.2 Volatile organic compounds at aqueous concentrationsgreater than about 1 mg/L can generally be determined bydirect aqueous injectio
4、n gas chromatography.1.3 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 t
5、o use.2. Referenced Documents2.1 ASTM Standards:3D1129 Terminology Relating to WaterD1192 Guide for Equipment for Sampling Water and Steamin Closed Conduits4D1193 Specification for Reagent WaterD3370 Practices for Sampling Water from Closed ConduitsE260 Practice for Packed Column Gas ChromatographyE
6、355 Practice for Gas Chromatography Terms and Rela-tionships3. Terminology3.1 DefinitionsThe following terms in this practice aredefined in accordance with Terminology D1129.3.1.1 “ghosting” or memory peaksan interference, show-ing as a peak, which appears at the same elution time as theorganic comp
7、onent of previous analysis.3.1.2 internal standarda material present in or added tosamples in known amount to serve as a reference measurement.3.1.3 noisean extraneous electronic signal which affectsbaseline stability.3.1.4 relative retention ratiothe retention time of theunknown component divided b
8、y the retention time of theinternal standard.3.1.5 retention timethe time that elapses from the intro-duction of the sample until the peak maximum is reached.3.2 For definitions of other chromatographic terms used inthis practice, refer to Practice E355.4. Summary of Practice4.1 This practice define
9、s the applicability of various col-umns and conditions for the separation of naturally occurringor synthetic organics or both, in an aqueous medium forsubsequent detection with a flame ionization detector. Aftervaporization, the aqueous sample is carried through the columnby an inert carrier gas. Th
10、e sample components are partitionedbetween the carrier gas and a stationary liquid phase on an inertsolid support. The column effluent is burned in an air-hydrogenflame. The ions released from combustion of the organiccomponents induce an increase in standing current which ismeasured. Although this
11、method is written for hydrogen flamedetection, the basic technology is applicable to other detectorsif water does not interfere.4.2 The elution times are characteristic of the variousorganic components present in the sample, while the peak areas1This practice is under the jurisdiction of ASTM Commit
12、tee D19 on Water andis the direct responsibility of Subcommittee D19.06 on Methods for Analysis forOrganic Substances in Water.Current edition approved May 1, 2011. Published June 2011. Originallyapproved in 1970. Last previous edition approved in 2005 as D2908 91 (2005).DOI: 10.1520/D2908-91R11.2Th
13、e boldface numbers in parentheses refer to the list of references at the end ofthis practice.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
14、Summary page onthe 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.are proportional to the quantities of the components. A di
15、scus-sion of gas chromatography is presented in Practice E260.5. Significance and Use5.1 This practice is useful in identifying the major organicconstituents in wastewater for support of effective in-plant orpollution control programs. Currently, the most practical meansfor tentatively identifying a
16、nd measuring a range of volatileorganic compounds is gas-liquid chromatography. Positiveidentification requires supplemental testing (for example, mul-tiple columns, speciality detectors, spectroscopy, or a combi-nation of these techniques).6. Interferences6.1 Particulate MatterParticulate or suspen
17、ded mattershould be removed by centrifugation or membrane filtration ifcomponents of interest are not altered. This pretreatment willprevent both plugging of syringes and formation of condensa-tion nuclei. Acidification will often facilitate the dissolving ofparticulate matter, but the operator must
18、 determine that pHadjustment does not alter the components to be determined.6.2 Identical Retention TimesWith any given column andoperating conditions, one or more components may elute atidentical retention times. Thus a chromatographic peak is onlypresumptive evidence of a single component. Confirm
19、ationrequires analyses with other columns with varying physical andchemical properties, or spectrometric confirmation of theisolated peak, or both.6.3 AcidificationDetection of certain groups of compo-nents will be enhanced if the sample is made neutral or slightlyacidic. This may minimize the forma
20、tion of nonvolatile salts incases such as the analysis of volatile organic acids and basesand certain chlorophenols.6.4 GhostingGhosting is evidenced by an interferencepeak that occurs at the same time as that for a component froma previous analysis but usually with less intensity. Ghostingoccurs be
21、cause of organic holdup in the injection port. Re-peated Type I water washing with 5-L injections betweensample runs will usually eliminate ghosting problems. Thebaseline is checked at maximum sensitivity to assure that theinterference has been eliminated. In addition to water injec-tions, increasin
22、g the injection port temperature for a period oftime will often facilitate the elimination of ghosting problems.6.4.1 Delayed ElutionHighly polar or high boiling com-ponents may unpredictably elute several chromatograms laterand therefore act as an interference. This is particularly truewith complex
23、 industrial waste samples. A combination ofrepeated water injections and elevated column temperature willeliminate this problem. Back flush valves should be used if thisproblem is encountered often.7. Apparatus7.1 Gas System:7.1.1 Gas RegulatorsHigh-quality pressure regulatorsshould be used to ensur
24、e a steady flow of gas to the instrument.If temperature programming is used, differential flow control-lers should be installed in the carrier gas line to prevent adecrease in flow as the pressure drop across the columnincreases due to the increasing temperature. An unsteady flowwill create an unsta
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