Determination of thiabendazole in citrus fruits by ultraviolet spectrophotometry

Abstract

A method for the ultraviolet spectrophotometric determination of thiabendazole in citrus fruit is described. It is extracted from the fruits by equilibrating the mashed peels or pulps with chloroform, the extract is acidified and the mixture concentrated in order to eliminate the chloroform and filtered. After making the filtrate slightly alkaline the thiabendazole is re-extracted with chloroform and determined by measuring the absorption of the extract at 302 to 303 nm. The procedure enables the satisfactory elimination of interfering substances to be achieved, and small amounts of thiabendazole of the order of 0·1 p.p.m. in the peel and the pulps and 0·03 p.p.m. in the whole fruit to be determined. The recovery of thiabendazole added to the peel or pulp of fruit varies between 94·1 and 103·0 per cent.