DETERMINATION OF THIABENDAZOLE RESIDUES IN PEARS BY SOLID-PHASE SPECTROFLUOROMETRY

An analytical procedure for determination of thiabendazole (TBZ) residues in pears is described. The method involves extracting the chemical from the chopped fruit with buffer solution (acetic acid-acetate, pH 4.6), use of Sephadex G-15 dextran-type gel as a solid support, and determination of TBZ by solid-phase spectrofluorimetry (SPF). The relative fluorescence intensity of the Sephadex G15 gel-TBZ system, packed in a 1 mm-thickness silica cell, was measured directly at lambda(ex) = 303 nm and lambda(em) = 350 nm with a solid-phase attachment. The applicable concentration range was 5.0-20.0 ppb with a detection limit of 0.5 ppb. Recoveries were from 98.7 to 102.0% when 15.0 ppb of TBZ was added to the fruit.