ASTM_E_1787_-_08.pdf

Designation:E178708Standard Test Method forAnions in Caustic Soda and Caustic Potash(SodiumHydroxide and Potassium Hydroxide)by IonChromatography1This standard is issued under the fixed designation E1787;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.Scope*1.1 This test method covers the determination of anionicimpurities in 50%caustic soda(sodium hydroxide)and 50%caustic potash(potassium hydroxide)solutions using ionchromatography(IC).Anions that can be determined at con-centrations of approximately 0.11000 ug/g(ppm)include:bromide,chlorate,chloride,fluoride,nitrate,phosphate,andsulfate.1.2 By varying the sample size,this test method can be usedfor anhydrous caustic soda and caustic potash products,as wellas other concentrations of liquid products.1.3 This test method is not intended to be used to quantifychloride in caustic soda where the sodium chloride concentra-tionisapproximately1%.Forthemostaccuratedeterminations,it is recommended that high concentrations ofchloride be analyzed using a potentiometric titration procedure,such as the one described in Test Methods E291.1.4 The values stated in SI units are to be regarded asstandard.The values given in parentheses are for informationonly.1.5 Review the current appropriate Material Safety DataSheets(MSDS)for detailed information concerning toxicity,first aid procedures,and safety precautions.1.6 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.Specific hazardsstatements are given in Section 8.2.Referenced Documents2.1 ASTM Standards:2D1193 Specification for Reagent WaterE180 Practice for Determining the Precision of ASTMMethods for Analysis and Testing of Industrial and Spe-cialty Chemicals(Withdrawn 2009)3E291 Test Methods for Chemical Analysis of Caustic Sodaand Caustic Potash(Sodium Hydroxide and PotassiumHydroxide)3.Summary of Test Method3.1 Bromide,chlorate,chloride,fluoride,nitrate,phosphateand sulfate are measured in NaOH or KOH by ion chromatog-raphy.The sample solution is diluted and injected onto asample loop of an automated neutralization module.Thesample in the loop is pumped to a suppression device whichuses electrolysis to neutralize the hydroxide ions.The samplethen is circulated through this device several times until it iscompletely neutralized.Anionic constituents of the neutralizedsample are concentrated on an anion concentrator column.After the concentration they are separated into individualelution bands in the eluent on a separator column.Theconductivity of the eluent is reduced with an anion suppressiondevice,and the anions of interest are detected using a conduc-tivity detector.Quantitation of the anions in the samplesolution is achieved by calibrating the IC with a series ofstandards containing known amounts of the anions.Thesestandards are also passed through the neutralization device.4.Significance and Use4.1 Anion impurities in caustic soda and caustic potash aremonitored by manufacturers and users for quality control of the1This test method is under the jurisdiction of ASTM Committee E15 onIndustrial and Specialty Chemicals and is the direct responsibility of SubcommitteeE15.01 on General Standards.Current edition approved April 1,2008.Published May 2008.Originallypublished in 1996.Last previous edition approved in 2002 as E1787-02.DOI:10.1520/E1787-08.2For 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.3The last approved version of this historical standard is referenced onwww.astm.org.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 products.Anions of primary interest are chloride,chlorate,andsulfate.This test method has determined precision estimatesonly for these three impurities.5.Interferences5.1 Substances that coelute with the anions of interest willinterfere.A high concentration of one anion can interfere withaccurate quantitation of another anion if their retention timesare close and resolution is affected.For example,caustic sodasamples containing large concentrations of chloride can inter-fere with the quantitation of small amounts of fluoride.Selection of a high capacity anion separator column willminimize this problem.5.2 Organic acids,surfactants,dyes,metals,etc.,can causefouling of the columns and membranes used in this testmethod,resulting i