Determination of tricyclohexyltin hydroxide residues in apples and pears

Plictran (tricyclohexyltin hydroxide, Cy₃SnOH) residues in Stark Delicious apples and Passacrassana pears were determined. Field applications were carried out 7, 16 and 28 days before harvest. The analyses were carried out by two procedures: selective determination of the various Sn forms and determination of total Sn. The final spectrophotometric determinations were made as inorganic Sn using dithiol reagent. Average data obtained for apples were from 0.26 to 0.32 ppm of Sn (0.84–1.00 ppm Cy₃SnOH) and for pears from 0.12 to 0.30 ppm of Sn (040–0.99 ppm Cy₃SnOH). A residues half-life of 5–6 weeks for the apples and of 2 weeks for the pears was found.