Simultaneous Determination of Residual Chlorine and Volatile Chlorinated Organic Compounds in Vegetables by the Head Space Method

Abstract

In order to elucidate the mechanism of formation of volatile chlorinated organic compounds (VCOC) from vegetables treated with sodium hypochlorite, simultaneous determination of residual chlorine and VCOC was studied. A sample was added to a head space analysis vessel filled in advance with phosphate buffer (pH 7.0) and potassium cyanide, then the vessel was sealed and allowed to stand for 30 minutes. The obtained gas was subjected to ECD-GC for determination. The substance formed in soybean sprouts immersed in sodium hypochlorite solution (200ppm) was identified as chloroform by GC/MS. Residual chlorine and chloroform were detected in the sprouts at levels of 12.1μg/g and 114ng/g respectively. The analysis of 66 samples of commercially available vegetables with the present method revealed residual chlorine ranging from 0.14 to 3.7μg/g and chloroform from 15 to 241ng/g in four samples of soybean sprouts, etc.