ASTM_D_4655_-_95_2012.pdf

Designation:D465595(Reapproved 2012)Standard Test Methods forSulfates in Leather(Total,Neutral,and Combined Acid)1This standard is issued under the fixed designation D4655;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.This standard has been approved for use by agencies of the Department of Defense.1.Scope1.1 These test methods are intended for use in determiningthe total,neutral,and combined acid sulfate in mineral-tannedleather.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 and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2D2813 Practice for Sampling Leather for Physical andChemical TestsD4654 Test Method for Sulfate Basicity in Leather3.Significance and Use3.1 These test methods are used to determine the basicity ofleather when used in accordance with Test Method D4654.4.Apparatus4.1 Volumetric Flask,250 mL.4.2 Filter paper,ashless,fine grained and porcelain crucible.4.3 Crucible,Gooch,with porous porcelain filter(optional).5.Reagents5.1 Ammonium Hydroxide Solution,(0.1 N)7 mL/L re-agent grade concentrate NH4OH.Optional:Potassium dihydro-gen phosphate,0.1 molar solution(13.6 g/L KH2PO4)orsodium dihydrogen phosphate,0.1 molar solution(13.8 g/LNaH2PO4-H2O).5.2 Hydrochloric Acid Solution,(1.5 N)125 mL/L reagentgrade concentrate hydrochloric acid.5.3 Barium Chloride Solution(BaCl22H2O),1%.5.4 Sodium Hydroxide Solution,0.01 N,0.4 g/L.5.5 Mixed Indicator,consisting of 60 mLof a 0.1%solutionof methyl red and 40 mLof a 0.1%solution of methylene blue,both in 95%alcohol.6.Sampling,Test Specimens,and Test Units6.1 The specimen for each determination shall consist of 1g leather from the composite sample(See Practice D2813).6.2 Two specimens from the composite sample shall betested for each determination.7.Procedure7.1 Total SulfatesWeigh the specimen to the nearest mil-ligram and record the value as W1.Transfer the specimen to a250-mL volumetric flask and add 200 mL of 0.1 N ammoniumhydroxide or 0.1 molar potassium or sodium dihydrogenphosphate solution.Immerse the flask up to the neck in a bathof boiling water.Thoroughly wet all products by swirlingoccasionally.After 2 h cool the flask to room temperature,andmake up to volume with distilled water,shake,and withoutdelay filter through a folded filter paper.Discard the first 20 to25 mL of the filtrate.Pipette 200 mL of the filtrate into a 600mL beaker and add about 20 mL of 1.5 N hydrochloric acid.Heat the solution to boiling and while boiling and stirring thesolution,add 20 mL of a 1%solution of barium chloridedropwise.Keep the covered beaker in a warm place at least for2 h and preferably overnight.7.1.1 Filter the precipitate through a fine grained ashlessfilter paper and wash with hot water until free from chloride.Aweighed Gooch crucible or a weighed porous crucible may beused as an alternative for the filtration.Transfer the paper withthe precipitate to a weighed crucible and ignite gently,eitherover a gas burner or in a muffle oven at 900C for 1 h.Cool thecrucible in a desiccator,weigh,and record the value of theBaSO4as W2.1These test methods are under the jurisdiction of ASTM Committee D31 onLeather and are the direct responsibility of Subcommittee D31.06 on ChemicalAnalysis.This test method was developed in cooperation with theAmerican LeatherChemists Assn.(Method D201956).Current edition approved April 1,2012.Published April 2012.Originallyapproved in 1987.Last previous edition approved in 2006 as D465595(2006).DOI:10.1520/D4655-95R12.2For 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 7.2 Neutral SulfatesWeigh the specimen to the nearestmilligram and record the value as W3.Transfer the specimen toa 250-mL volumetric flask and add 200 mL of distilled water.Immerse the flask up to the neck in boiling water.Thoroughlywet all particles by swirling occasionally.After 2 h cool flaskto room temperature,make up to volume with distilled water,shake and without delay filter through a folded filter.Discardthe first 20 to 25 mLof the filtrate.Pipette 200 mLof the filtrateinto a 600-mL beaker and titrate with 0.01 N sodiumhydroxide,using a few drops of the methyl red/methylene blueindicator.Record t