Integrated three-electrode screen-printed sensor modified with bismuth film for voltammetric determination of thallium(I) at the ultratrace level

Highlights: • Integrated three-electrode screen-printed sensor was used for Tl(I) determination. • In situ plating of bismuth film increases sensor sensitivity. • The method allows Tl(I) quantification at picomolar concentrations. • The sensor was successfully applied for analysis of Tl(I) in water samples. - Abstract: In the present paper, for the first time, the integrated three-electrode screen-printed sensor with in situ plated bismuth film carbon working electrode was applied for the ultratrace determination of thallium(I) (Tl(I)). Under optimized conditions extremely low limits of detection were reached, 8.47 × 10^-10 and 6.71 × 10^-12 mol L^-1 for the deposition times of 60 s and 300 s, respectively. The influences of foreign metal ions and surfactants on the voltammetric signal of thallium in natural samples were minimized using 1 × 10^-5 mol L^-1 EDTA and Amberlite XAD-7 resin added to the buffer solution (CH₃COONH₄, CH₃COOH and NH₄Cl) of pH = 4.6 ± 0.1. The developed voltammetric method with integrated three-electrode screen-printed sensor was validated with use of certified reference materials (surface, rain and natural water) and can be in future applied to field analyses of Tl(I).