Electrochemical Behavior of Dibutyltin(IV) Compounds and Their Determination at ppb Levels by Differential Pulse Anodic Stripping Voltammetry

Abstract

Abstract The electrochemical behavior of dibutyltin(IV) compounds (Bu2SnX2) (X=chloride, laurate (L), and 6-methylheptyl maleate (MHM)) in 50% (v/v) and 80% (v/v) ethanol–water media (apparent pH 7.3) containing 0.002% Triton X-100 has been investigated by polarography and cyclic voltammetry. It has been found that Bu2SnX2 gives a two-electron transfer step at about −0.8 V vs. SCE, which consists of very close two one-electron steps, and a two-electron step at about −1.4 V in both media. Over the potential range of either side of the first reduction wave, both Bu2SnX2 and their reduction products are significantly adsorbed on the surface of a mercury electrode in 50% (v/v) ethanol, but not in 80% (v/v) ethanol. The adsorbed reduction products are readily re-oxidized at the mercury electrode in 50% ethanol. The re-oxidation peak was successfully utilized for the determination of traces of Bu2SnCl2 by means of the differential pulse anodic stripping voltammetry (DPASV) over the concentration range of 3–50 ppb (μg dm−3) at the deposition time of 60 s. The DPASV behavior of Bu2SnX2 (X=chloride, L, MHM, and 1-dodecanethiolate) has been investigated in a 50% ethanol medium in detail. Further, a procedure has been developed for determining Bu2SnX2 in natural water down to ppb levels.