Thin Layer Chromatography with Post-Chromatographic Iodine-Azide Reaction for Thiuram Analysis in Food Samples

Abstract

A simple, sensitive, precise, and rapid planar chromatographic method for thiuram analysis was elaborated. Reaction between iodine and azide ions induced by thiuram was applied as a detection system. The developed plates were sprayed with freshly prepared mixtures of sodium azide and starch solution adjusted to pH 6.0, and exposed to iodine vapor. The spots became visible as white spots on a violet-grey background. The iodine-azide detection system was proved to be the most favorable and enabled detection of quantities at the level 0.5 pmol per spot. The iodine-azide test was compared with other visualizing techniques commonly used in planar chromatography: iodine vapor, UV 254 , Cu(II). Certain factors that influence detection with iodine-azide reaction as a detection system were checked. The developed method was linear over the concentration range of 2-9 pmol per spot. The proposed technique was applied to detect thiuram in food samples.