ImageVerifierCode 换一换
格式:PDF , 页数:18 ,大小:206.30KB ,
资源ID:527248      下载积分:5000 积分
快捷下载
登录下载
邮箱/手机:
温馨提示:
如需开发票,请勿充值!快捷下载时,用户名和密码都是您填写的邮箱或者手机号,方便查询和重复下载(系统自动生成)。
如填写123,账号就是123,密码也是123。
特别说明:
请自助下载,系统不会自动发送文件的哦; 如果您已付费,想二次下载,请登录后访问:我的下载记录
支付方式: 支付宝扫码支付 微信扫码支付   
注意:如需开发票,请勿充值!
验证码:   换一换

加入VIP,免费下载
 

温馨提示:由于个人手机设置不同,如果发现不能下载,请复制以下地址【http://www.mydoc123.com/d-527248.html】到电脑端继续下载(重复下载不扣费)。

已注册用户请登录:
账号:
密码:
验证码:   换一换
  忘记密码?
三方登录: 微信登录  

下载须知

1: 本站所有资源如无特殊说明,都需要本地电脑安装OFFICE2007和PDF阅读器。
2: 试题试卷类文档,如果标题没有明确说明有答案则都视为没有答案,请知晓。
3: 文件的所有权益归上传用户所有。
4. 未经权益所有人同意不得将文件中的内容挪作商业或盈利用途。
5. 本站仅提供交流平台,并不能对任何下载内容负责。
6. 下载文件中如有侵权或不适当内容,请与我们联系,我们立即纠正。
7. 本站不保证下载资源的准确性、安全性和完整性, 同时也不承担用户因使用这些下载资源对自己和他人造成任何形式的伤害或损失。

版权提示 | 免责声明

本文(ASTM E260-1996(2011) 3125 Standard Practice for Packed Column Gas Chromatography《填料塔气相色谱法的标准操作规程》.pdf)为本站会员(wealthynice100)主动上传,麦多课文库仅提供信息存储空间,仅对用户上传内容的表现方式做保护处理,对上载内容本身不做任何修改或编辑。 若此文所含内容侵犯了您的版权或隐私,请立即通知麦多课文库(发送邮件至master@mydoc123.com或直接QQ联系客服),我们立即给予删除!

ASTM E260-1996(2011) 3125 Standard Practice for Packed Column Gas Chromatography《填料塔气相色谱法的标准操作规程》.pdf

1、Designation: E260 96 (Reapproved 2011)Standard Practice forPacked Column Gas Chromatography1This standard is issued under the fixed designation E260; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A numb

2、er 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 is intended to serve as a general guide tothe application of gas chromatography (GC) with packedcolumns for the separation an

3、d analysis of vaporizable orgaseous organic and inorganic mixtures and as a reference forthe writing and reporting of GC methods.NOTE 1This practice excludes any form of gas chromatographyassociated with open tubular (capillary) columns.1.2 This standard does not purport to address all the safetycon

4、cerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety andhealth practices and determine the applicability of regulatorylimitations prior to use. Specific hazard statements are given inSection 8 and 9.1.3.2. Referenced Documents2.

5、1 ASTM Standards:2E355 Practice for Gas Chromatography Terms and Rela-tionshipsE516 Practice for Testing Thermal Conductivity DetectorsUsed in Gas ChromatographyE594 Practice for Testing Flame Ionization Detectors Usedin Gas or Supercritical Fluid ChromatographyE697 Practice for Use of Electron-Capt

6、ure Detectors in GasChromatographyE840 Practice for Using Flame Photometric Detectors inGas ChromatographyE1140 Practice for Testing Nitrogen/Phosphorus Thermi-onic Ionization Detectors for Use In Gas Chromatography2.2 CGA Publications:3CGA P-1 Safe Handling of Compressed Gases in Contain-ersCGA G-5

7、.4 Standard for Hydrogen Piping Systems at Con-sumer LocationsCGA P-9 The Inert Gases: Argon, Nitrogen and HeliumCGA P-12 Safe Handling of Cryogenic LiquidsCGA V-7 Standard Method of Determining Cylinder ValveOutlet Connections for Industrial Gas MixturesHB-3 Handbook of Compressed Gases3. Terminolo

8、gy3.1 Terms and relations are defined in Practice E355 andreferences therein.4. Summary of Practice4.1 Ablock diagram of the basic apparatus needed for a gaschromatographic system is as shown in Fig. 1. An inert,pressure or flow-controlled carrier gas flowing at a measuredrate passes to the injectio

9、n port or gas sample valve. A sampleis introduced into the injection port, where it is vaporized, or ifgaseous, into a gas sample valve, and then swept into andthrough the column by the carrier gas. Passage through thecolumn separates the sample into its components. The effluentfrom the column passe

10、s to a detector where the response ofsample components is measured as they emerge from thecolumn. The detector electrical output is relative to theconcentration of each resolved component and is transmitted toa recorder, or electronic data processing system, or both, toproduce a record of the separa

11、tion, or chromatogram, fromwhich detailed analysis can be obtained. The detector effluentmust be vented to a hood if the effluent contains toxicsubstances.4.2 Gas chromatography is essentially a physical separationtechnique. The separation is obtained when the sample mixturein the vapor phase passes

12、 through a column containing astationary phase possessing special adsorptive properties. The1This practice is under the jurisdiction of ASTM Committee E13 on MolecularSpectroscopy and Separation Science and is the direct responsibility of Subcom-mittee E13.19 on Separation Science.Current edition ap

13、proved Nov. 1, 2011. Published December 2011. Originallyapproved in 1965. Last previous edition approved in 2006 as E260 96 (2011).DOI: 10.1520/E0260-96R11.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of AST

14、MStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from Compressed Gas Association (CGA), 4221 Walney Rd., 5thFloor, Chantilly, VA 20151-2923, http:/.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-

15、2959, United States.degree of separation depends upon the differences in thedistribution of volatile compounds, organic or inorganic, be-tween a gaseous mobile phase and a selected stationary phasethat is contained in a tube or GC column. In gas-liquidchromatography (GLC), the stationary phase is a

16、nonvolatileliquid or gum coated as a thin film on a finely-divided, inertsupport of a relatively large surface area, and the distribution isbased on partition. The liquid phase should not react with, andshould have different partition coefficients for, the variouscomponents in the sample. In gas-sol

17、id chromatography(GSC), the stationary phase is a finely divided solid adsorbent(see 4.4).4.2.1 After separation in the analytical column, the compo-nents are detected, and the detector signal is related to theconcentration of the volatile components. Tentative identifica-tions can be made by compar

18、ison with the retention times ofknown standards under the same conditions, either on a singlecolumn or preferably by injecting the sample onto two columnsof different selectivity. Ancillary techniques, such as massspectrometry or infrared spectrophotometry, are generally nec-essary for positive iden

19、tification of components in samples.4.2.2 Prior to performing a GC analysis, the followingparameters must be considered:4.2.2.1 Sample preparation.4.2.2.2 Stationary phase and loading on support.4.2.2.3 Column material required.4.2.2.4 Solid support and mesh size.4.2.2.5 Column length and diameter.4

20、.2.2.6 Instrument and detector type that will be needed.4.2.2.7 Injector, column oven, and detector temperaturesrequired for analysis.4.2.2.8 Injection techniques, such as flash volatilization,on-column technique, purge and trap, pyrolysis, etc.4.2.2.9 Carrier gas and flow rate.4.2.2.10 Data handlin

21、g and presentation.4.3 In gas-liquid chromatography, the degree of separationpossible between any two compounds (solutes), is determinedby the ratio of their partition coefficients and the separationefficiency. The partition coefficient, K, is the ratio of the soluteconcentration in the liquid phase

22、 to the solute concentration inthe vapor phase at equilibrium conditions. The partition coef-ficient is affected by temperature and the chemical nature of thesolute (sample) and solvent (stationary phase).4.4 Another mechanism for separation is gas-solid chroma-tography. With this technique there is

23、 no liquid phase, only aporous polymer, molecular sieve, or solid adsorbent. Partitionis accomplished by distribution between the gas phase and thesolid phase.4.5 After the sample is resolved into individual componentsby the chromatographic column, the concentration or massflow of each component in

24、the carrier gas can be measured byan appropriate detector which sends an electrical signal to arecording potentiometer or other readout device. The curveobtained by plotting detector response against time is referredto as a chromatogram. For flame ionization and thermalconductivity detectors, either

25、 the peak areas or the peak heightsare proportional to the concentration of the components in thesample within the linear range of the detector system. How-ever, response fractors are not necessarily the same for allcompounds, and linearity of detector response may depend onoperating conditions. (Te

26、sting of detector performance isdiscussed in ASTM Standard Practices for the appropriatedetector, see 2.1).4.6 Components in a mixture may be tentatively identifiedby retention time. Ideally, each substance has a unique reten-tion time in the chromatogram for a specific set of operatingconditions. H

27、owever, caution is required because the GCseparation may be incomplete and a single peak may representmore than one compound. This is especially true of unknownmixtures and complex mixtures because of the very largenumber of possible compounds in existence and the finitenumber of peaks that a chroma

28、tograph might resolve. Addi-tional characterization data may be provided by ancillarytechniques, such as spectrometry.5. Significance and Use5.1 This practice describes a procedure for packed-columngas chromatography. It provides general comments, recom-mended techniques, and precautions.Arecommende

29、d form forreporting GC methods is given in Section 14.6. Apparatus6.1 Carrier Gas SystemCommon carrier gases are heliumand nitrogen. 7.6 provides more details on carrier gases. Meansmust be provided to measure and control the flow rate of thecarrier gas. Any flow or pressure control and measurementc

30、ombination may be used that will give an accurately knownand reproducible flow rate over the desired range.6.1.1 The main gas supply is regulated with a two-stageregulator which must have a stainless steel diaphragm. RubberFIG. 1 Block Diagram of a Basic Gas Chromatographic SystemE260 96 (2011)2or p

31、lastic diaphragms permit oxygen or water to diffuse into thecarrier gas. In addition, instruments will have a flow controllerbetween the pressure regulator and column inlet to maintain aconstant flow during temperature programming. Copper orstainless steel carrier gas lines, not plastic tubing, shou

32、ld beused to avoid diffusion of oxygen (air) into the carrier gas.When using the thermal conductivity detector, variations in theflow will change retention and response. The carrier gas linepressure must be higher than that required to maintain thecolumn flow at the upper temperature limit for the f

33、lowcontroller to operate properly. A pressure of 40 to 60 psi isusually sufficient.6.2 Column Temperature ControlPrecise column tem-perature control is mandatory if reproducible analyses are to beobtained. Temperature control must be within 0.1C if reten-tion times are to be compared with another in

34、strument.6.2.1 Air BathThe thermostated forced-air bath is gener-ally accepted as the best practical method of temperatureregulation for most applications. Temperatures can be con-trolled by regulators or proportionally controlled heaters usinga thermocouple or platinum-resistance thermometer as a s

35、ens-ing element. The advantage of a forced-air bath is the speed oftemperature equilibration. Air bath ovens are readily adaptableto temperature programming and are capable of operating overa range of 35 to 450C. This range can be extended downto 100C by using cryogenic equipment.6.2.2 Other Devices

36、Liquid baths, drying ovens, incuba-tors, or vapor jacket enclosures are less stable, less convenientmeans of providing a source of heat to maintain or raise thetemperature of a chromatographic column. These devices arenot recommended for precision chromatographic applications.6.3 The Injection PortT

37、he purpose of the injection port isto introduce the sample into the gas chromatographic columnby instantaneous volatilization following injection into the gaschromatographic system. Two sample inlet types are in com-mon use in gas chromatography: the flash vaporization and theon-column injection inl

38、ets.6.3.1 The temperature of the flash vaporization inlet shouldbe above the boiling points of the sample components and islimited by the amount of septum bleed generated and thetemperature stability of sample components. It should be set atthat temperature above which no improvement in peak shapeoc

39、curs but should be determined by the nature of the sampleand the volume injected, not by the temperature of the column.If the inlet temperature is too low, broad peak with a slowlyrising front edge will result from slow vaporization of thesample. If the temperature is set far above what is necessary

40、 toproduce fast vaporization, thermal decomposition of thesample, decreased septum life, and ghost peaks due to septumbleed may be observed. Generally, a good guideline is tomaintain the inlet temperature 25 to 30C higher than thehighest boiling point of any sample component.6.3.2 A glass liner plac

41、ed inside the injection port willeliminate sample contact with hot metal inner walls of the inlet,which can catalyze thermal decompositions. Any debris left inthe liner, especially from biological samples, can be a source ofexcessive sample adsorption. If a liner is used, the debris caneasily be rem

42、oved by replacing the liner. Deactivation of theglass liner by treatment with dimethyldichlorosilane may benecessary for some compounds.6.3.3 With on-column injection technique, the sample isdeposited in the liquid state directly on the column packing.The sample must be small enough to preclude floo

43、ding of thecolumn, with possible detrimental effects to peak shape andcolumn life. Ideally, the on-column inlet is a part of thecolumn, so its temperature may be controlled as the columntemperature is controlled. In practice, because an on-columninlet usually has a somewhat higher thermal mass than

44、anequivalent sector of the rest of the column, the inlet must beheated somewhat above the maximum analysis temperature ofthe column oven. The criteria of good peak shape andquantitation should be used to determine the maximum re-quired temperature for the inlet. One should consider thetemperature li

45、mit of the column packing when heating theinjection inlet and detector. With some samples, a nonheatedinjection port is adequate, especially with temperature-programmed operation.6.3.4 Injection Port Septum:6.3.4.1 The septum is a disc, usually made of siliconerubber, which seals one end of the inje

46、ction port. It is importantto change the septum frequently after two to three dozeninjections, or preferably at the end of the working day. The besttechnique is to change the septum when the column isrelatively cool (below 50C) to avoid contact of stationaryphase in a hot column with air (danger of

47、oxidation). After theseptum is changed, return the inlet temperature to that whichwas originally set. The inlet temperature should be the opti-mum for the particular analysis, as well as within the recom-mended operating temperature of the septum. If the septum ispunctured too many times, it will le

48、ak air into the gaschromatographic system, even though it is under pressure. Athigh temperatures, above 150 to 200C, air (oxygen) in thecarrier gas from a septum leak will degrade the stationaryphase. An excessive septum leak will also produce a change incarrier gas flow rate (a change in retention

49、time) and loss ofsample (irreproducible peak heights) due to outflow from theleak. When installing the septum, do not overtighten theretaining nut. The septa will swell at high temperature andextrude out of the injection port.Asnug fit at room temperatureis sufficient. It is important for septum life to make sure theinjection needle is sharp with no bent tip. Fine emery cloth, ora fine sharpening stone, can be used to sharpen the point.6.3.4.2 Ghost peaks may be observed in temperature pro-grammed runs due to septum bleed. Septum bleed is due to thetherm

copyright@ 2008-2019 麦多课文库(www.mydoc123.com)网站版权所有
备案/许可证编号:苏ICP备17064731号-1