ASTM_D_8451_-_22.pdf

Designation:D845122Standard Test Method forCalculation of Unfixed Chrome Concentration in Wet Blue1This standard is issued under the fixed designation D8451;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 procedures to analyze andcalculate unfixed chrome concentrations in Wet Blue.1.2 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.3 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.1.4 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:2D6658 Test Method for Volatile Matter(Moisture)of WetBlue by Oven DryingD6659 Practice for Sampling and Preparation of Wet Blueand Wet White for Physical and Chemical TestsE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3.Terminology3.1 Definitions:3.1.1 unfixed chrome,nchrome that is not chemicallybound to hide substance and may be removed by waterextraction.4.Summary of Test Method4.1 The sample is soaked,static,in deionized water for 20 to24 h.After 20 to 24 h of static soaking,the mixture isthoroughly mixed,an aliquot filtered(and diluted)if necessary,is analyzed for unfixed chrome content.Atomic AbsorptionSpectrophotometers using the nitrous oxide/acetylene flame orthe air/acetylene flame are acceptable to use for the analysis.Analysis by the ICP(Inductively Coupled Plasma)method isalso acceptable.5.Significance and Use5.1 This test method measures the amount of unfixedchrome in Wet Blue.Results may vary according to the age ofthe Wet Blue.6.Apparatus6.1 Leather Cutting Tool.6.2 Styrofoam Cup,or 250 mL beaker.6.3 Beaker,250 mL capacity or equivalent.6.4 Beaker,1000 mL capacity or equivalent.6.5 Volumetric Flask,200 mL capacity or equivalent.6.6 Volumetric Flask,1000 mL capacity or equivalent.6.7 Stirring Rod.6.8 Magnetic Stirrer.6.9 Atomic Absorption Spectrophotometer.6.10 ICP.6.11 Scale,accurate to 0.0001 g.6.12 Filter Paper,Whatman 1 or equivalent.6.13 Hot Plate,to be placed inside exhaust or fume hood.7.Reagents and Materials7.1 Purity of ReagentsAnalytical Reagent(AR)Gradeshall be used in all tests.Unless otherwise indicated,it isintended that all reagents conform to the specifications of theCommittee on Analytic Reagents of the American ChemicalSociety(ACS),where such specifications are available.Othergrades may be used,provided it is first ascertained that thereagent is of sufficiently high purity to permit its use withoutlessening the accuracy of determination.1This test method is under the jurisdiction of ASTM Committee D31 on Leatherand is the direct responsibility of Subcommittee D31.02 on Wet Blue.Current edition approved April 1,2022.Published May 2022.DOI:10.1520/D8451-22.2For 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 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.17.2 Commercial ReagentsThe use of commercially avail-able pre-standardized analytical reagents and solutions isappropriate,providing those reagents and solutions have beenprepared in accordance with and conform to the previouslymentioned specifications(see 7.1).7.3 Purity of WaterUnless otherwise indicated,referenceto water shall be understood to mean deionized water.7.4 Commercial Cr Standard,1000 ppm.NOTE1Subsections 7.5 to 7.10 only apply when nitrous oxide/acetylene flame is used.7.5 Oxalic Acid Anhydrous,H2C2O4Formula weight=90.03 or oxalic acid dihydrate,H2C2O42H2O Formulaweight=126.07.NOTE2For conversion purposes,1 g of the anhydrous form isequivalent to 1.4 g of the dihydrate form.7.6 Potassium Dichromate(K2Cr2O7)Used in standardC