ASTM_E_1642_-_00_2010.pdf

Designation:E164200(Reapproved 2010)Standard Practice forGeneral Techniques of Gas Chromatography Infrared(GC/IR)Analysis1This standard is issued under the fixed designation E1642;the number immediately following the designation indicates 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 practice covers techniques that are of general use inanalyzing qualitatively multicomponent samples by using acombination of gas chromatography(GC)and infrared(IR)spectrophotometric techniques.The mixture is separated intoits individual components by GC and then these individualcomponents are analyzed by IR spectroscopy.Types of GC-IRtechniques discussed include eluent trapping,flowcell,andeluite deposition.1.2 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.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 to use.2.Referenced Documents2.1 ASTM Standards:2E131 Terminology Relating to Molecular SpectroscopyE168 Practices for General Techniques of Infrared Quanti-tative AnalysisE260 Practice for Packed Column Gas ChromatographyE334 Practice for General Techniques of Infrared Micro-analysisE355 Practice for Gas Chromatography Terms and Relation-shipsE932 Practice for Describing and Measuring Performance ofDispersive Infrared SpectrometersE1252 Practice for General Techniques for Obtaining Infra-red Spectra for Qualitative AnalysisE1421 Practice for Describing and Measuring Performanceof Fourier Transform Mid-Infrared(FT-MIR)Spectrom-eters:Level Zero and Level One TestsE1510 Practice for Installing Fused Silica Open TubularCapillary Columns in Gas Chromatographs3.Terminology3.1 DefinitionsFor definitions of terms and symbols,referto Terminology E131 and Practice E355.4.Significance and Use4.1 This practice provides general guidelines for the properpractice of gas chromatography coupled with infrared spectro-photometric detection and analysis(GC/IR).This practiceassumes that the chromatography involved in the practice isadequate to separate the compounds of interest.It is not theintention of this practice to instruct the user how to perform gaschromatography properly.5.General GC/IR Techniques5.1 Three different types of GC/IR technique have beenused to analyze samples.These consist of analyte trapping,flowcell,or lightpipe,and direct eluite deposition and arepresented in the order that they were first used.5.2 The GC eluent must not be routed to a destructive GCdetector(such as a flame ionization detector)prior to reachingthe IR detector as this will destroy or alter the individualcomponents.It is acceptable to split the eluent so that part ofthe stream is directed to such a detector or to pass the streamback to the detector after infrared analysis if such techniquesare feasible.5.3 Eluent Trapping TechniquesAnalyte trapping tech-niques are the least elaborate means for obtaining GC/IR data.In these techniques,the sample eluting from the chromato-graph is collected in discrete aliquots to be analyzed.Inutilizing such techniques,it is essential that a GC detector beemployed to allow definition of component elution.If adestructive detector is employed,then post-column splitting tothat detector is required.GC fractions can be trapped in thecondensed phase by passing the GC effluent through a solvent,a powdered solid,or a cold trap for subsequent analysis(see1This practice is under the jurisdiction of ASTM Committee E13 on MolecularSpectroscopy and Separation Science and is the direct responsibility of Subcom-mittee E13.03 on Infrared and Near Infrared Spectroscopy.Current edition approved March 1,2010.Published April 2010.Originallyapproved in 1994.Last previous edition approved in 2005 as E1642 00(2005).DOI:10.1520/E1642-00R10.2For 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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 Practice E1252)(1).3Vapor phase samples can be trapped in aheated low-volume gas cell at the exit of the GC,analyzed,then flushed with the continuing GC effluent until the nextaliquot of interest is in the gas cell when the flow is stoppedagain for analysis(2).Since the analyte of interest is staticwhen employing an analyte trapping technique,the spectrumcan be recorded using a long co-addition time to improve thesignal-to-noise(SNR)ratio.However,in analyte trapping,sample integrity