Colorimetric Estimation of Citric Acid

Abstract

A NUMBER of analyses have been developed^{1, 2, 3} whereby citric acid can be estimated with varying degrees of sensitivity. Some¹ are usable for only small quantities of citric acid in solution, while others^{2, 3} possess a considerably wider range but are complicated either by reagents or by the sensitivity of the determination at the higher levels. For the most part these methods are difficult to handle and vary in their sensitivity from day to day. The method of Cartier and Pin, for example, can be used to determine reasonably wide ranges (100–1200 µgm.) of citric acid; but the reagent used for the development of the colour reaction is light-sensitive and may interfere with the estimation. The methods of Natalson et al. and Buffa and Peters, on the other hand, are complicated by the fact that the reagent used to decolorize the permanganate (hydrogen peroxide) interferes with the colour reaction, and considerable care must be taken to remove all traces of it.