1、Designation: D4655 95 (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
2、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 intend
3、ed 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,
4、 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 and
5、Chemical 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 cruc
6、ible.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/ LNaH
7、2PO4-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 mL of a 0.1 %solution of methyl red and 40 mL of a 0.1 % solution ofm
8、ethylene 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 Su
9、lfatesWeigh the specimen to the nearestmilligram and record the value as W1. Transfer the specimen toa 250-mL volumetric flask and add 200 mL of 0.1 N ammo-nium hydroxide or 0.1 molar potassium or sodium dihydrogenphosphate solution. Immerse the flask up to the neck in a bathof boiling water. Thorou
10、ghly 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 a
11、dd 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 grai
12、ned 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
13、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 w
14、ith 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, orc
15、ontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.7.2 Neutral Sulfate
16、sWeigh 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
17、, 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 sodium hydrox-ide, using a few drops of the methyl red/methylene blueindicator. Reco
18、rd the results as mL 0.01 N NaOH. Afteraddition of 4 to 5 mL of 1.5 N hydrochloric acid, heat thesolution to boiling. While boiling and stirring the solution, add10 mL of a 1 % barium chloride solution dropwise. Keep thecovered beaker in a warm place at least for 2 h and preferablyovernight.7.2.1 Fo
19、llow the directions for filtration given in 7.1.1.Record the value of the BaSO4as W4.8. Calculation of Results8.1 Calculate the total sulfate content of the specimen asfollows:% total sulfate SO4! 5 W23 .4115/W13 250/200 3 100 (1)where:W1= the weight of the specimen, andW2= the weight of the BaSO4.8
20、.2 Calculate the neutral sulfate content of the specimen asfollows:% neutral sulfate SO4! 5 W43 .4115 2 N3 A 3 .048!/W33 250/250 3 100 (2)where:W3= the weight of the specimen,W4= the weight of the BaSO4,A = the millilitre of standard NaOH, andN = the normality of the standard NaOH.8.3 Calculate the
21、combined acid sulfate content of thespecimen as follows:% combined acid sulfate SO4!5 % total sulfate 2 % neutral sulfate.(3)8.3.1 The total, neutral and combined acid sulfates in thesample for test shall be the average of the test results obtainedfrom the specimens tested.9. Report9.1 Unless otherw
22、ise specified in the detail specification, theresults shall be reported to the nearest 0.1 %.10. Precision and Bias10.1 This test method is adopted from the procedures of theAmerican Leather ChemistsAssociation where it has long beenin use and where it was approved for publication before theinclusio
23、n of precision and bias statements were mandated. Theoriginal interlaboratory test data is no longer available. Theuser is cautioned to verify by the use of reference material ifavailable that the precision and bias of this test method isadequate for the contemplated use.11. Keywords11.1 combined ac
24、id sulfate; mineral tanned leather; neutralsulfates; total sulfatesASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any
25、such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are inv
26、ited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received
27、 a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of th
28、is standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).D4655 95 (2012)2
