ANALYSIS, SORPTION AND RESIDUES OF A HOMOLOGOUS SERIES OF ISOTHIOCYANATES ON WHEAT

A series of isothiocyanates (R-NCS, R, 1-6 carbon atoms) was applied i n the vapour phase to wheat in sealed containers. The speed of sorptio n, as measured by the rate of loss from the intergranular air space, w as inversely proportional to molecular weight; e.g. the time for 50% s orption of hexyl isothiocyanate was over 100 times longer than for the methyl analogue. Despite extensive sorption, most of the applied chem icals was recovered from the fumigated wheat seven days after dosing, indicating that sorption did not lead to extensive degradation. Purge and trap techniques proved suitable for recovery of low-boiling, but n ot high-boiling chemicals.