ASTM_D_7785_-_21.pdf

Designation:D778521Standard Practice forWater in Lint Cotton by Oven Evaporation Combined withVolumetric Karl Fischer Titration1This standard is issued under the fixed designation D7785;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 the determination of the totalamount of water(free and bound)in raw and lint cotton atmoisture equilibrium from conditioning in the standard atmo-sphere for testing textiles.NOTE1For other methods of determination of moisture in lint cottonthat do not specify conditioning to moisture equilibrium,refer to TestMethods D2495 and D1348.1.2 This practice requires the use of oven evaporation toremove all of the water in the fiber matrix,volumetric KarlFischer(KF)titration to determine water content and waterregain,and control current potentiometry to detect the endpoint.1.3 This practice is not intended for use with potentiometric(zero current)and coulometric Karl Fischer titrators(see TestMethods D1533,D4377 and E1064),nor is this practiceintended to be used with methanol extracts of cotton(See TestMethods D1348).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,health,and environmental practices and deter-mine the applicability of regulatory limitations prior to use.For specific precautionary warnings see 9.1.1.6 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade(TBT)Committee.2.Referenced Documents2.1 ASTM Standards:2D123 Terminology Relating to TextilesD1193 Specification for Reagent WaterD1348 Test Methods for Moisture in Cellulose(Withdrawn2017)3D1441 Practice for Sampling Cotton Fibers for TestingD1533 Test Method for Water in Insulating Liquids byCoulometric Karl Fischer TitrationD1776 Practice for Conditioning and Testing TextilesD2495 Test Method for Moisture in Cotton by Oven-DryingD4377 Test Method for Water in Crude Oils by Potentiomet-ric Karl Fischer Titration(Withdrawn 2020)3D7139 Terminology for Cotton FibersE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE203 Test Method for Water Using Volumetric Karl FischerTitrationE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE1064 Test Method for Water in Organic Liquids by Coulo-metric Karl Fischer Titration3.Terminology3.1 Definitions:3.2 For all terminology relating to D13.11,Cotton Fibers,refer to Terminology D7139.3.3 The following terms are relevant to this standard:boundwater,free water,test specimen,water content,water regain.3.4 For definitions of all other textile terms see TerminologyD123.4.Summary of Practice4.1 A0.1 g test specimen is sealed in a glass vial,positionedon the sample turntable and lowered into the single sample1This practice is under the jurisdiction ofASTM Committee D13 on Textiles andis the direct responsibility of Subcommittee D13.11 on Cotton Fibers.Current edition approved Jan.1,2021.Published February 2021.Originallypublished in 2012.Last previous edition approved in 2012 as D7785-12.DOI:10.1520/D7785-21.2For 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 StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade(TBT)Committee.1oven where dry nitrogen transports the water vapor that israpidly evaporated from the fibers into a titration cell.Theamount of water is determined by volumetric titration withKarl Fischer reagent with the end point determined by elec-trodes that measure a sharp change in potential when the iodinein the reagent is reduced by sulfur dioxide in the presence ofwater.The volume of reagent required to titrate the wet gasstream is converted into the amount of water in the testspecimen.For the reaction mechanism and the chemica