ASTM_E_1698_-_95_2010.pdf

Designation:E169895(Reapproved 2010)Standard Practice forTesting Electrolytic Conductivity Detectors(ELCD)Used inGas Chromatography1This standard is issued under the fixed designation E1698;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 testing the performance of anelectrolytic conductivity detector(ELCD)used as the detectioncomponent of a gas chromatographic system.1.2 This practice is directly applicable to electrolytic con-ductivity detectors that perform a chemical reaction on a givensample over a nickel catalyst surface under oxidizing orreducing conditions and employ a scrubber,if needed,toremove interferences,deionized solvent to dissolve the reac-tion products,and a conductivity cell to measure the electro-lytic conductivity of ionized reaction products.1.3 This practice covers the performance of the detectoritself,independently of the chromatographic column,in termsthat the analyst can use to predict overall system performancewhen the detector is coupled to the column and other chro-matographic system components.1.4 For general gas chromatographic procedures,PracticeE260 should be followed except where specific changes arerecommended herein for the use of an electrolytic conductivitydetector.For definitions of gas chromatography and its variousterms see Practice E355.1.5 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.6This 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:2E260 Practice for Packed Column Gas ChromatographyE355 Practice for Gas Chromatography Terms and Relation-ships3.Significance and Use3.1 Although it is possible to observe and measure each ofthe several characteristics of the ELCD under different andunique conditions,in particular its different modes ofselectivity,it is the intent of this practice that a complete set ofdetector specifications should be obtained at the same operat-ing conditions,including geometry,gas and solvent flow rates,and temperatures.It should be noted that to specify a detectorscapability completely,its performance should be measured atseveral sets of conditions within the useful range of thedetector.The terms and tests described in this practice aresufficiently general so that they may be used at whateverconditions may be chosen for other reasons.3.2 Linearity and speed of response of the recorder usedshould be such that it does not distort or otherwise interferewith the performance of the detector.Effective recorder re-sponse should be sufficiently fast so that it can be neglected insensitivity of measurements.If additional amplifiers are usedbetween the detector and the final readout device,theircharacteristics should also first be established.4.Principles of Electrolytic Conductivity Detectors4.1 The principle components of the ELCD are representedin Fig.1 and include:a control module,a reactor assembly,and,a cell assembly.4.1.1 The control module typically will house the detectorelectronics that monitor or control,or both,the solvent flow,1This 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 approved Nov.1,2010.Published November 2010.Originallyapproved in 1995.Last previous edition approved in 2005 as E1698 95(2005).DOI:10.1520/E1698-95R10.2For 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 reaction temperatures,and the conductivity detector cell.It canbe functionally independent of the gas chromatography or,insome varieties,designed into the functional framework of thegas chromatograph.However,the reactor and cell assembliesare designed for specific models of gas chromatographs so it isimportant the proper components be assembled on the appro-priate chromatographic equipment.4.2 Fig.2 is a block diagram representation of the GC/ELCD system.The electrolytic conductivity detector detectscompounds by pyrolyzing those compounds in a heated nickelcatalyst(housed in the reactor),removing interfering reactionproducts with a scrubber(if needed),dissolving the reactionproducts in a suitable solvent,and measuring the ch