Determination of Saponification Value in Carnuba Wax by USP/NF Residual Titration Method <541>

Abstract

Saponification value is defined as mg KOH needed to neutralize free acids and saponify esters in 1 g of the test substance. A search of the literature showed that the standard saponification methods of the U.S. Pharmacopeia, alcoholic potassium hydroxide were the only saponification reagent. The sample to investigate is saponified with an excess of ethanolic potassium hydroxide solution. After finished saponification the remaining excess of potassium hydroxide is determined by residual titration under Titrimetry <541>, with aqueous volumetric hydrochloric acid. In this study, a test for saponification value has been successfully determined in carnuba wax. The average result has been found 90.9 mg KOH/g substance and, % RPD was 1.65%. This is in contradistinction to the U.S. Pharmacopeia/National Formulary (USP/NF) Method.