1、 FORD LABORATORY TEST METHOD AK 101-01 Date Action Revisions 2001 01 22 Revised Editorial no technical change A. Cockman 2000 03 22 Revised Editorial no technical change A. Cockman 1992 04 29 Printed copies are uncontrolled Page 1 of 2 Copyright 2001, Ford Global Technologies, Inc. DETERMINATION OF
2、BUFFER VALUE OF SOAP Application This method is used to determine the buffer value of soap compounds such as powdered hand soap. The buffer value is the number of mL of 0.1 N H2SO4 required to titrate one gram, to a pH of 7.0, of the water soluble salts in the soap compound after the removal of the
3、soap with alcohol. Solutions and Apparatus Required Alcohol Ethyl or “3A“ alcohol Phenolphthalein 0.2 g of phenolphthalein dissolved in 50 mL of ethyl alcohol and diluted with 50 mL of distilled water. Methyl Orange 0.1 g dissolved in 100 mL of distilled water. Sulphuric Acid - 0.1 N Accurately meas
4、ure 2.9 mL of H2SO4 (conc.) and dilute to 1000 mL with distilled water. Standardize as follows: Weigh 0.1 to 0.2 g of pure sodium carbonate and dissolve in 100 mL of distilled water in a 300 mL Erlenmeyer flask. Add 3 drops of methyl orange and titrate to a permanent reddish tint. Weight of Na 2CO 3
5、 = Normality mL of H2SO4 x 0.053 pH Meter A Macbeth pH meter or similar instrument preferably equipped with a mechanical stirrer. FORD LABORATORY TEST METHOD AK 101-01 Page 2 of 2 Copyright 2001, Ford Global Technologies, Inc. Conditioning and Test Conditions All test values indicated herein are bas
6、ed on material conditioned in a controlled atmosphere of 23 +/- 2 C and 50 +/- 5 % relative humidity for not less than 24 h prior to testing and tested under the same conditions unless otherwise specified. Procedure Weigh 2.0 g of the sample and transfer to a 400 mL beaker. Mix with 200 mL of alcoho
7、l and digest on a water bath for at least 30 minutes. Filter through a Gooch crucible and wash the insolubles well with alcohol. Dry the insolubles in an oven at 100 C for one hour to remove alcohol. Char the organic matter at approximately 425 - 535 C until only carbon and ash remain and cool. Wash
8、 the ash with hot neutral distilled water until the washings are colorless to phenolphthalein. Transfer the washings to a 250 mL beaker and dilute to 100 mL with distilled water. Titrate, using a mechanical stirrer, with 0.1 N H2SO4 to an end point of 7 as indicated by the pH meter using a glass ele
9、ctrode. mL of 0.1 N H 2SO 4 = Buffer Value in mL Weight of Sample Note: The alcohol insoluble, water soluble portion from the soap determination may be used instead of starting a new sample. Chemicals, materials, parts, and equipment referenced in this document must be used and handled properly. Each party is responsible for determining proper use and handling in its facilities.
