A colorimetric method for the determination of chloral hydrate

Abstract

A specific colorimetric method for the determination of chloral hydrate is described. The method is based on the measurement of the pink colour formed when chloral hydrate is treated with 2-thiobarbituric acid. It is specific for chloral hydrate as no other related compounds tested, such as chloroform, trichloroacetic acid, trichloroethylene, carbon tetrachloride, 2,2-dichloroethanol and 1,1,2,2-tetrachloroethane, give any coloration with 2-thiobarbituric acid. The method is sensitive to concentrations as low as 50 µg ml^–1 of chloral hydrate with a reproducibility of ±2 per cent.