1、Designation: D 4655 95 (Reapproved 2006)Standard Test Methods forSulfates in Leather (Total, Neutral, and Combined Acid)1This standard is issued under the fixed designation D 4655; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, th
2、e year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) 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 int
3、ended 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 as thestandard.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of
4、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:2D 2813 Practice for Sampling Leather for Physical andChemical TestsD 4654 Test Method for Sulfate Basicit
5、y in Leather3. Significance and Use3.1 These test methods are used to determine the basicity ofleather when used in accordance with Test Method D 4654.4. Apparatus4.1 Volumetric Flask, 250 mL.4.2 Filter paper, ashless, fine grained and porcelain crucible.4.3 Crucible, Gooch, with porous porcelain fi
6、lter (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)1
7、25 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 ofmethylene blue, both in 95 % alcohol.6. Sampling, T
8、est Specimens, and Test Units6.1 The specimen for each determination shall consist of 1g leather from the composite sample (See Practice D 2813).6.2 Two specimens from the composite sample shall betested for each determination.7. Procedure7.1 Total SulfatesWeigh the specimen to the nearestmilligram
9、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. Thoroughly wet all products by swirlingoccasionally. Af
10、ter 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 th
11、e 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 u
12、ntil 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
13、, weigh, and record the value of theBaSO4as W2.7.2 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. Thoroughly1These test metho
14、ds 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 D 201956).Current edition approved Oct. 1, 2006. Published November
15、 2006. Originallyapproved in 1987. Last previous edition approved in 2001 as D 465595 (2001).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
16、Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.wet all particles by swirling occasionally. After 2 h cool flaskto room temperature, make up to volume with distilled water,shake and without delay filte
17、r 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. Record the results as mL 0.01 N NaOH. Afteraddition of 4 to 5 mL of 1.5 N
18、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 Follow the directions for filtration given in 7.1.1.Record the value of
19、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 BaSO4.8.2 Calculate the neutral sulfate content of the specimen asfollows:% n
20、eutral 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 combined acid sulfate content of thespecimen as follows:% combined aci
21、d 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 otherwise specified in the detail specification, theresults shall be reporte
22、d 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 theinclusion of precision and bias statements were mandated. Theoriginal interlab
23、oratory 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 acid sulfate; mineral tanned leather; neutralsulfates; total sulfatesAST
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27、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 this 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).D 4655 95 (2006)2
