1、Designation: D2810 13D2810 18Standard 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 U.S. Department of Defense.1. Scope1.1 This test method covers the determination of the pH of all types of leather.
3、This method does not apply to wet blue.blueor wet white.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 r
4、esponsibilityof the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine theapplicability of regulatory limitations prior to use.1.4 This international standard was developed in accordance with internationally recognized principles on
5、standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:D2813 Practice for Sampling Leather for Phys
6、ical and Chemical Tests3. Terminology3.1 Definitions of Terms Specific 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 alkalin
7、ity.3.1.2 The pH difference figure (delta pH) is the difference between the pH of a solution and its ten-fold dilution.4. Significance and Use4.1 This test method is designed to measure the pH of a distilled-water distilled water extract of leather. This is considered tobe a measure of the acidity o
8、r alkalinity of the leather. Excessive acidity or alkalinity may have a deleterious effect on the agingcharacteristics of leather.4.2 This test method is suitable for development, control, and service evaluation of leather.5. Interferences5.1 If the leather contains an excessive amount of fats or gr
9、eases 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 treated by any of the following procedures:5.2.1 A vacuum may be used to effect wetting.5.2.2 Mix
10、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 evaporated; then proceed as outlined in Section 10.1 This test method is under the jurisdiction of ASTM
11、 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 Assn. (Standard Method B20 1969).Current edition approved May 1, 2013Sept. 1, 2018. Published May 2013September 2018
12、. Originally approved in 1969. Last previous edition approved in 20072013 asD2810 07.D2810 13. DOI: 10.1520/D2810-13.10.1520/D2810-18.2 A Waring Blender has been found satisfactory.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of wha
13、t 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 appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the
14、 official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States16. Apparatus6.1 Electronic pH Meter, either battery or line-operated with a suitable electrode. The meter shall have a resolution of 0.1/0.01an accuracy of at least 0.
15、01 pH unit, and shall have a relative accuracy of 60.1/0.01reproducibility of 0.05 pH unit.6.2 Analytical Balance, sensitive to 0.01 g.g or greater.7. Reagents7.1 Purity of ReagentsReagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that allreagents shall c
16、onform 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 the reagent is of sufficiently highpurity to permit its use without lessening the accuracy o
17、f 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 5.5 nor more than 7.0 and shall give a residue of not more than0.5 mg, when 100 mL is eva
18、porated and dried in a platinum dish.7.3 Standard Commercially Standardized pH Solutions:47.3.1 Alkaline Phosphate Buffer Solution (0.01 M trisodium phosphate, pH = 11.72 at 25C25 C)Dissolve 1.42 g ofanhydrous disodium hydrogen phosphate (Na2HPO4) in 100 mL of a 0.1 N carbonate-free solution of sodi
19、um hydroxide (NaOH)and dilute to 1 L with water.7.3.2 Borax Buffer Solution (0.01 M, pH = 9.18 at 25C)25 C)Dissolve 3.81 g of sodium tetraborate decahydrate(Na2B4O7 10 H2O) in water and dilute to 1 L.7.3.3 Hydrochloric Acid (pH = 1.10 at 25C25 C)Add 2 g of concentrated hydrochloric acid (HCl, sp gr
20、1.19) to 450 g ofwater. 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 25C25 C )Dissolve 3.40 g ofmonobasic potassium phosphate (KH2PO4) and 3.55 g of anhydrous dibasic sodium phosphate (Na2HPO4) in water and dilute to1 L.7.
21、3.5 Potassium Hydrogen Phthalate Buffer Solution (0.05 M, pH = 4.01 at 25C25 C)Dissolve 10.21 g of potassiumhydrogen phthalate (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 sample prepared according to Practice D2813
22、.9. 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. Thoroughly rinse the electrodes with water.9.2 Thoroughly rinse electrode with water and establi
23、sh a fresh liquid junction after blotting electrodes if using sleeve typeelectrode prior to testing each solution. Use manufacturers directions for establishing two point standardization with standard pHsolutions that read on either side of the anticipated pH of the solution to be tested.9.3 Check f
24、or 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 the specimen. Stopper the flasks and agitate thoroughly. Le
25、t stand at the Standard LaboratoryTemperature, 23.0 6 1C (73.46 1.8F), 1 C (73.4 6 1.8 F), with occasional agitation for not less than 4 nor more than 18 h.Agitate thoroughly and transfer to a clean beaker or decant if possible.10.2 Rinse the electrode with water and immerse in the test solution to
26、determine the pH of the leather-water mixture or solution.Read the meter to the nearest 0.01 unit. Rinse the electrodes with water again and repeat with the second test specimen.10.3 If a pH difference figure (delta pH) is desired, remove a 5 mL to 10 mL aliquot of the liquid into a beaker and dilut
27、eten-fold. Mix well and determine the pH. Calculate the difference in pH from the initial reading.NOTE 1If the pH difference figure is 0.7 or greater, it is an indication that a strong free acid is present.11. Report11.1 Report the following information:3 Reagent Chemicals, American Chemical Society
28、 Specifications , American Chemical Society, Washington, DC. For suggestions on the testing of 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. Pharmacopei
29、al Convention, Inc. (USPC), Rockville, MD.4 Buffer salts and solutions prepared in accordance with National Bureau of Standards recommendations are sold by reputable laboratory supply houses and may be used.D2810 18211.1.1 The individual values or the average, or both, of pH of the sample shall be r
30、eported to the nearest 0.05 pH unit exceptwhen establishing repeatability or reproducibility then report each determination separately to 0.01 pH units.11.1.2 The pH difference figure (delta pH) shall be reported to the nearest 0.05 pH unit12. Precision and Bias12.1 RepeatabilityThe average differen
31、ce between two results (each the average of duplicate determinations), obtained by thesame analysis on different days, 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 differe
32、nce between two results (each the average of duplicate determinations) obtained byanalysis in different laboratories will approximate 0.02 pH units. Two such values should be considered suspect (95 % confidencelevel) if they differ by more than 0.06 units.NOTE 2Variance analysis of the pH data is on
33、 file as a research report at ASTM Headquarters.5 It was developed from a round-robin test involvingfive laboratories and four leathers.13. Keywords13.1 acidity; alkalinity; delta pH; pH; pH differenceASTM International takes no position respecting the validity of any patent rights asserted in conne
34、ction with any item mentionedin this standard. Users of this standard are expressly advised that determination of 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 responsi
35、ble technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn.Your 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 con
36、sideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments 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
37、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 web
38、site(www.astm.org). Permission rights to photocopy the standard may also be secured from the Copyright Clearance Center, 222Rosewood Drive, Danvers, MA 01923, Tel: (978) 646-2600; http:/ Supporting data have been filed at ASTM International Headquarters and may be obtained by requesting RR:D31-1002.D2810 183
