1、Designation: D2810 07D2810 13Standard Test Method forpH of Leather1This standard is issued under the fixed designation D2810; 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 indica
2、tes 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 This test method covers the determination of the pH of all types of leather. This
3、method does not apply to wet blue.1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the us
4、er of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:D2813 Practice for Sampling Leather for Physical and Chemical Tests3. Terminology3.1 Definitions of Terms Specific
5、to This Standard:3.1.1 The pH of a solution has been defined as the negative logarithm of the hydrogen ion activity.Asolution of pH 7 is neutralat 24C. Lower numbers indicate increasing acidity; higher numbers, increasing alkalinity.4. Significance and Use4.1 This test method is designed to measure
6、the pH of a distilled-water extract of leather. This is considered to be a measureof the acidity or alkalinity of the leather. Excessive acidity or alkalinity may have a deleterious effect on the aging characteristicsof leather.4.2 This test method is suitable for development, control, and service e
7、valuation of leather.5. Interferences5.1 If the leather contains an excessive amount of fats or greases or has been treated with a material to obtain water repellency,the wettability and consequently the extractability may be affected.5.2 If the specimen is difficult or impossible to wet, it may be
8、treated by any of the following procedures:5.2.1 A vacuum may be used to effect wetting.5.2.2 Mix with the required amount of water for 1 min in a disintegrator.25.2.3 Extract the weighed specimen with a fat solvent in a Soxhlet apparatus for 5 h. Allow the specimen to air until all solventhas evapo
9、rated; then proceed as outlined in Section 910.6. Apparatus6.1 pH Meter, either battery or line-operated,line-operated with a glass electrode and reference electrode or suitablecombination suitable electrode. The meter shall have a resolution of 0.1/0.01 pH unit, and shall have a relative accuracy o
10、f60.1/0.01 pH unit.6.2 Analytical Balance, sensitive to 0.01 g.1 This test method is under the jurisdiction of ASTM Committee D31 on Leather and is the direct responsibility of Subcommittee D31.06 on Chemical Analysis. This testmethod was developed in cooperation with the American Leather Chemists A
11、ssn. (Standard Method B20 1969).Current edition approved April 1, 2007May 1, 2013. Published May 20072013. Originally approved in 1969. Last previous edition approved in 20012007 asD2810 01.D2810 07. DOI: 10.1520/D2810-07.10.1520/D2810-13.2 A Waring Blender has been found satisfactory.This document
12、is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appro
13、priate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States17. Reagents7.1 Purity of ReagentsReagent grade chemicals shall
14、 be used in all tests. Unless otherwise indicated, it is intended that allreagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society, wheresuch specifications are available.3 Other grades may be used, provided it is first ascertained that th
15、e reagent is of sufficiently highpurity to permit its use without lessening the accuracy of the determination.7.2 Purity of WaterUnless otherwise indicated, references to water shall be understood to mean distilled water or water ofequal purity. Distilled water shall have a pH value of not less than
16、 5.5 nor more than 7.0 and shall give a residue of not more than0.5 mg, when 100 mL is evaporated and dried in a platinum dish.7.3 Standard pH Solutions:47.3.1 Alkaline Phosphate Buffer Solution (0.01 M trisodium phosphate, pH = 11.72 at 25C)Dissolve 1.42 g of anhydrousdisodium hydrogen phosphate (N
17、a2HPO4) in 100 mL of a 0.1 N carbonate-free solution of sodium hydroxide (NaOH) and diluteto 1 L with water.7.3.2 Borax Buffer Solution (0.01 M, pH = 9.18 at 25C)Dissolve 3.81 g of sodium tetraborate decahydrate (Na2B4O7 10H2O) in water and dilute to 1 L.7.3.3 Hydrochloric Acid (pH = 1.10 at 25C)Add
18、 2 g of concentrated hydrochloric acid (HCl, sp gr 1.19) to 450 g of water.Standardize and dilute to 0.1 N.7.3.4 Phosphate Buffer Solution (0.025 M with respect to each phosphate, salt pH = 6.86 at 25C )Dissolve 3.40 g ofmonobasic potassium phosphate (KH2PO4) and 3.55 g of anhydrous dibasic sodium p
19、hosphate (Na2HPO4) in water and dilute to1 L.7.3.5 Potassium Hydrogen Phthalate Buffer Solution (0.05 M, pH = 4.01 at 25C)Dissolve 10.21 g of potassium hydrogenphthalate (KHC8H4O4) in water and dilute to 1 L.8. Test Specimen8.1 The specimen shall consist of from 2 to 5 g of leather from a composite
20、sample prepared according to anPracticeD2813accepted procedure9. Standardization9.1 Before the pH of the solution is measured, turn the instrument on, allow it to warm up thoroughly, and bring to electricalbalance in accordance with the manufacturers instructions. Wash the glass and calomel electrod
21、es and the beaker three times withwater and dry gently with clean, absorbent tissue. If a sleeve-type calomel reference electrode is used, form a fresh liquid junctionby moving the sleeve.Thoroughly rinse the electrodes with water.9.2 Set temperature dial to the temperature of the solution. Use manu
22、facturers directions for establishing two pointstandardization with standard pH solutions that read on either side of the anticipated pH of the solution to be tested. Washelectrodes by immersing in three changes of water and establish a fresh liquid junction after blotting electrodes if using sleeve
23、 typeelectrode prior to testing each solution.9.3 Check for electrode drift with either of the buffers and restandardize if necessary.10. Procedure10.1 Weigh the specimen in duplicate to the nearest 0.1 g and transfer to 250-mL Erlenmeyer flasks. Add water in the amountof twenty times the mass of th
24、e specimen. Stopper the flasks and agitate thoroughly. Let stand at the Standard LaboratoryTemperature, 23.0 6 1C (73.46 1.8F), with occasional agitation for not less than 4 nor more than 18 h. Agitate thoroughly andtransfer to a clean beaker or decant if possible.10.2 Determine the Rinse the electr
25、ode with water and immerse in the test solution to determine the pH of the leather-watermixture or solution. First wash and blot the electrodes and establish a fresh liquid junction if using a sleeve-type electrode. Immersethe electrodes in the test solution and read the Read the meter to the neares
26、t 0.01 unit. CleanRinse the electrodes with water againand repeat with the second test specimen.11. Report11.1 Report the following information:11.1.1 The individual values or the average, or both, of pH of the sample shall be reported to the nearest 0.05 pH unit asdetermined by the average of the r
27、esults obtained from the specimens tested except when establishing repeatability orreproducibility then report each determination separately to 0.01 pH units.3 Reagent Chemicals, American Chemical Society Specifications , , American Chemical Society, Washington, DC. For suggestions on the testing of
28、 reagents not listed bythe American Chemical Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and NationalFormulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.4 Buffer salts and solutions prepared in accordance
29、with National Bureau of Standards recommendations are sold by reputable laboratory supply houses and may be used.D2810 13212. Precision and Bias12.1 RepeatabilityThe average difference between two results (each the average of duplicate determinations), obtained by thesame analysis on different days,
30、 will approximate 0.01 pH units. Two such values should be considered suspect (95 % confidencelevel) if they differ by more than 0.03 pH units.12.2 ReproducibilityThe average difference between two results (each the average of duplicate determinations) obtained byanalysis in different laboratories w
31、ill approximate 0.02 pH units. Two such values should be considered suspect (95 % confidencelevel) if they differ by more than 0.06 units.NOTE 1Variance analysis of the pH data is on file as a research report at ASTM HeadquartersHeadquarters.5 as RR: D-31-1002. It was developedfrom a round-robin tes
32、t involving five laboratories and four leathers.13. Keywords13.1 acidity; alkalinity; pHASTM 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
33、 the validity of any 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.Y
34、our comments are invited 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 commen
35、ts have not received 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 mu
36、ltiple 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). Permission rights to photocopy the standard may also be secured from the ASTM website (www.as
37、tm.org/COPYRIGHT/).5 Acceptable procedures are published in theSupporting data have been filed at Journal of the Americal Leather Chemists Assn., JALCA, Vol 5, 1956, p. 497; or OfficialMethods ofAnalysis,Am. Leather ChemistsAssn., available through the Office of Secretary-Treasurer, Campus Station, Cincinnati, Ohio 45221; or seeASTM MethodASTMInternational D2813, Sampling Leather for Physical and Chemical Tests,Headquarters and may be Annual Book ofobtained by requesting RR:D31-1002ASTM Standards,.Vol 15.04.D2810 133
