ASTM_E_2679_-_09.pdf

Designation:E267909Standard Test Method forAcidity in Mono-,Di-,Tri-and Tetraethylene Glycol byNon-Aqueous Potentiometric Titration1This standard is issued under the fixed designation E2679;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 test method covers the determination of totalacidity as acetic acid in commonly available grades of mono-ethylene glycol,diethylene glycol,triethylene glycol andtetraethylene glycol using a non-aqueous potentiometric titra-tion.This test method is useful for determining low levels ofacidity,below 200 mg/kg.1.2 The mono-,di-,tri-and tetraethylene glycols can beanalyzed directly by this test method without any samplepreparation.1.3 Review the current appropriate Material Safety DataSheets(MSDS)for detailed information concerning toxicity,first aid procedures,and safety precautions.1.4 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.5 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 the section on Hazards,Section 9.2.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Practice for Determining the Precision of ASTMMethods for Analysis and Testing of Industrial and Spe-cialty Chemicals(Withdrawn 2009)33.Terminology3.1 Definitions:3.1.1 aciditythe amount of total acid titrated with anaqueous base(KOH or NaOH)in a sample of ethylene glycol.The acidity is calculated as acetic acid in mg/kg.4.Summary of Test Method4.1 An aliquot of a mono-,di-,tri-or tetraethylene glycolsample is weighed and titrated potentiometrically with amonotonic or dynamic mode of titrant addition using anaqueous base(NaOH or KOH)solution to determine the acidcontent in milligrams of acid as acetic acid per kilogram ofsample.An ethylene glycol sample can be analyzed directly bythis test method without any sample preparation using acombination pH electrode with an inert ethanol electrolytedesigned for non-aqueous titrations.The potentiometric titra-tion readings in millivolts are plotted automatically against therespective volumes of the titrating solution and the end point isidentified by a well-defined inflection in the resulting curve.5.Significance and Use5.1 This test method provides for the quantitative determi-nation of total acidity in ethylene glycols by non-aqueouspotentiometric titration.The run time for titration of ethyleneglycol samples ranges from 5 to 10 min with no samplepreparation required.The length of time for a titration dependson the amount of acidity in the sample and the acidity generallyincreases from monoethylene glycol to the higher glycols liketetraethylene glycol.5.2 Acceptable levels of acidity in ethylene glycols varywith the manufacturers specifications but are normally below200 mg/kg.Knowledge of the acidity in ethylene glycols isrequired to establish whether the product quality meets speci-fication requirements.6.Interferences6.1 Aqueous base solutions,such as the 0.01 mol/L KOH orNaOH titrant,may absorb carbon dioxide from the air toproduce carbonate ions in the titrant and change the concen-tration of the titrant.Care should be taken to minimize1This test method is under the jurisdiction of ASTM Committee E15 onIndustrial and Specialty Chemicals and is the direct responsibility of SubcommitteeE15.02 on Product Standards.Current edition approved April 1,2009.Published May 2009.DOI:10.1520/E2679-09.2For 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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 exposure of basic titrants to the air.Verify the concentration ofthe titrant(standardize the titrant)if prolonged exposure to theair occurs.6.2 Minimize exposure of the ethylene glycol samples to theair to avoid contamination.7.Apparatus7.1 Potentiometric TitratorAutomatic titration systemscapable of adding fixed increments of titrant at fixed timeintervals(monotonic)or variable titrant increments with elec-trode stability between increment additions(dynamic)withendpoint seeking capabilities as prescribed in the method.As aminimum,the automatic titration system shall meet the perfor-mance and specification requirements as warranted by themanu