1、Designation: D 1172 95 (Reapproved 2007)Standard Guide forpH of Aqueous Solutions of Soaps and Detergents1This standard is issued under the fixed designation D 1172; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last
2、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 This guide covers the preparation of aque
3、ous solutionsof soaps and detergents and the determination of their pH.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 the user of this standard to
4、 establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. Material SafetyData Sheets are available for reagents and materials. Reviewthem for hazards prior to usage.2. Referenced Documents2.1 ASTM Standards:2D 460 Test Methods for Sa
5、mpling and Chemical Analysisof Soaps and Soap ProductsD 501 Test Methods of Sampling and Chemical Analysis ofAlkaline DetergentsE70 Test Method for pH of Aqueous Solutions With theGlass Electrode3. Sampling3.1 The material shall be sampled in accordance with TestMethods D 460 or D 501, whichever is
6、applicable.4. Reagent4.1 Distilled Water or EquivalentDistilled water orequivalent shall be boiled thoroughly, or purged with CO2-freeair, to remove CO2and shall be protected with soda-lime orsoda-asbestos (Ascarite) while cooling and in storage. The pHof this water shall be between 6.2 and 7.2 at 2
7、5C. The residueon evaporation, when heated at 105C for 1 h, shall not bemore than 0.5 mg/L.5. Procedure for Synthetic Detergents5.1 Preparation of SolutionsWeigh 1 6 0.001 g of thesample (see Note 1 and Note 2) and transfer to a 1-Lvolumetric flask. Partially fill the flask with distilled water oreq
8、uivalent and agitate until the sample is completely dissolved.Make certain the solute is completely dissolved and allow timefor the evolution of dissolved gases. Fill to the calibration markwith distilled water or equivalent. Stopper the flask; mixthoroughly. The desirable condition requires the sol
9、ution tocome to equilibrium. Allow the solution to equilibrate at 25 62.0C. The use of a temperature compensation probe mayallow alternate temperatures. Records should show the timeinterval between solution preparation and pH measurement.NOTE 1The procedure for detergents other than soaps is applica
10、ble tosome compositions that contain minor proportions of soap, provided thatthe solutions do not show evidence of gelling prior to carrying out the pHmeasurement.NOTE 2Measurements of pH of gelled solutions lack constancy andreproducibility. The procedure for soaps (Section 6) is designed to produc
11、esolutions that will not gel before the pH measurement is carried out. Thisprocedure should be used for all detergent solutions, soap or nonsoap, thatgive evidence of gelling or incomplete solution when prepared inaccordance with 5.1. The procedure for soaps is not applicable to detergentcomposition
12、s that are known to be chemically altered by the boiling waterused in dissolving the sample, or that are intended exclusively for use incold water.5.2 Determination of pHCalibrate the pH meter andsuitable electrodes. The recommended electrodes are FischerAccuphast combination electrode or Orion Ross
13、 Sure Flowelectrode or equivalent electrodes. Measure the pH of thesolution while stirring.6. Procedure for Soaps6.1 Preparation of ApparatusUse a pH meter and elec-trodes as defined in Test Method E70. Set the temperaturecontrol knob at 40C and standardize the assembly with asuitable buffer solutio
14、n in the pH 9 to 11 range at 40C. Leavethe electrode in the buffer to maintain temperature equilibrium.Have the apparatus ready for immediate use.6.2 Preparation of SolutionWeigh 0.30 6 0.01 g of thesample (see Note 2) and transfer to a 250-mL Erlenmeyer flask.Add 100 mL of boiling distilled water o
15、r equivalent that hasbeen boiled vigorously for 15 min just prior to use. Loosely1This guide is under the jurisdiction of ASTM Committee D12 on Soaps andOther Detergents and is the direct responsibility of Subcommittee D12.15 onPhysical Testing.Current edition approved Oct. 1, 2007. Published Octobe
16、r 2007. Originallyapproved in 1951. Last previous edition approved in 2001 as D 1172 95(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
17、 Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.stopper the flask with a clean, neutral, one-hole stopper fittedwith a suitable thermometer readable to the nearest 0.1C in the25 to 50C range and so ar
18、ranged that the thermometer bulbwill be completely immersed in the liquid.Agitate the flask andcontents to apparently complete solution of the sample; thencool rapidly under tap water to 43 6 0.5C. Promptly pourenough of the solution into the pH beaker to almost fill it.6.3 Determination of pHDeterm
19、ine the pH of the solutionat 40 6 2.0C, while stirring. The recommended electrodes areFisher Accuphast combination electrode or Orion Ross SureFlow electrode.ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standa
20、rd. 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 responsible technical committee and must be reviewe
21、d 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 consideration at a meeting of theresponsible
22、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 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 1172 95 (2007)2
