In situ bismuth-film electrode for square-wave anodic stripping voltammetric determination of tin in biodiesel

A bismuth-film electrode (BiFE) was applied in square-wave anodic stripping voltammetry (SWASV) in order to determine Sn (IV) in biodiesel samples. In situ simultaneous deposition of tin and bismuth at −1.2 V for 90 s was carried out in a supporting electrolyte containing 0.1 mol L−1 acetate buffer (pH 4.5) and 1.73 mmol L−1 caffeic acid as the complexing agent. A single well-defined anodic stripping peak was observed at −0.58 V for the oxidation of Sn to Sn (II), which was used as the analytical signal. The calibration curve was obtained in the concentration range of 0.17–7.83 μmol L−1 with the detection limit being 0.14 μmol L−1 (r = 0.9990). Repeatability and reproducibility for the measurement of the current peak were characterized by relative standard deviations of 3.6% and 4.1%, respectively, for a 5.0 μmol L−1 Sn (IV) solution (n = 10). The method was validated by comparing the results obtained with those provided by application of the atomic absorption spectroscopy technique.

► A bismuth-film electrode for tin determination. ► The sensor showed excellent performance. ► High levels of tin were found in biodiesel samples.