Non-aqueous titrimetric determination of food preservatives and non-nutritive sweeteners using internal indicators.

Oracet blue B, Sudan blue GN, Sudan green 4B (amino anthraquinone dyes) and resazurin have been used for the first time as internal indicators in the non-aqueous titrimetric detn. of food preservatives such as sodium benzoate, sodium propionate, sodium salicylate and non-nutritive sweeteners such as sodium saccharin and sodium cyclamate employing perchloric acid in glacial acetic acid as titrant. The suitability of using Azur A, Azur C, Toluidine blue O (thiazine dyes) and Bromo pyrogallol red in titrations employing sodium methoxide as titrant, for detn. of acid forms of the above preservatives and non-nutritive sweeteners, sorbic acid and p-hydroxybenzoic acid. The results are accurate with a max. % error of 0.1, 0.8 and 2.5 for macro, semi-micro and micro titrations resp. The recoveries of added preservatives and non-nutritive sweeteners to food products are reported. Photometric titrations are also described.