Complexation reaction of organotins with 3-hydroxyflavone and its application to their fluorometric determination

The kinetics and thermodynamics of the complexation reactions of monophenyltin (MPT), dimethyltin (DMT), dibutyltin (DBT), diphenyltin (DPT), trimethyltin (TMT), tributyltin (TBT) and triphenyltin (TPT) with 3-hydroxyflavone have been studied, and the results were applied to the fluorometric determination of organotins. The observed rate constant for the reactions hardly depended on the differences in the number and kind of organic substituent at tin. However, because the stability of the complexes was incresed in the order MPT > DPT ≫ TPT for phenyltins and DPT > DBT > DMT for di- substituted organotins, these differences were applied to the fluorometric determination of organotins. In the determination of the respective mono- and di-substituted organotins, MPT up to 5 μM, DMT up to 3 μM, DBT up to 4 μM and DPT up to 3 μM could be determined with a detection limit of 10, 20, 20 and 30 nM, respectively, and the tolerance level of tri-substituted organotins was relatively high. Noticeably, the presence of more than a 100-fold amount (by molarity) of TMT was successfully tolerated in the determination of 0.5 μM of any mono- or di-substituted organotin.