ASTM_D_7785_-_12.pdf

Designation:D778512Standard Test Method 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 test method 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 test method 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 test method is not intended for use with potentio-metric(zero current)and coulometric Karl Fischer titrators(seeTest Methods D1533,D4377 and E1064),nor is this testmethod intended to be used with methanol extracts of cotton(See Test Methods 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 and health practices and determine the applica-bility of regulatory limitations prior to use.For specificprecautionary warnings see 9.1.2.Referenced Documents2.1 ASTM Standards:2D123 Terminology Relating to TextilesD1193 Specification for Reagent WaterD1348 Test Methods for Moisture in CelluloseD1441 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 TitrationD7139 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 Test Method4.1 A0.1 g test specimen is sealed in a glass vial,positionedon the sample turntable and lowered into the single sampleoven 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 chemicalsinvolved with this test method,see Appendix X1.1This test method is under the jurisdiction ofASTM Committee D13 on Textilesand is the direct responsibility of Subcommittee D13.11 on Cotton Fibers.Current edition approved Feb.1,2012.Published March 2012.DOI:10.1520/D7785-12.2For 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 5.Significance and Use5.1 The water content of raw or lint cotton determined bythis test method,calculated from the required volume ofreagent,may be greater,equal to or less than the moisturecontent measured by standard oven drying methods.Thesedifferences may be of significance in commercial transactions(1-3)3(see also Appendix X2).Water content by this method isnot to be considered the same attribute as moisture content.5.2 Standard test methods using volumetric and coulometricKarl Fischer reagent are two of the most widely used proce-dures for the determination of water.5.3 The volumetric method is typically used for the routinedetermination of water in the mass percent range of concen-trations.If samples contain very low levels of water,thecoulometric technique