Chemically-modified carbon paste electrode for the voltammetric determination of bismuth

The paper deals with the preparation and analytical characterisation of a Bismuthiol II-carboxylate (5-mercapto-3-(p-carboxyphenyl)-1,3,4-thiadiazoline-2-thione) Modified Carbon Paste Electrode (BMCPE) to be used in the voltammetric analysis of bismuth. The influence of different experimental parameters (composition procedure, scan rate, etc.) on the electrode behaviour is evaluated. Bismuth can be determined by a stripping procedure in which it is non-electrochemically preconcentrated at the electrode (at open circuit) thank to the formation of a complex with the modifier present in the electrode surface. It is then reduced (stripped) by linearly scanning the potential (200 mV s(-1)) from -100 to -800 mV. Under suitable experimental conditions, bismuth can be determined from 1.5x10(-8) mol l(-1) (5 min of preconcentration time) to 6x10(-6) mol l(-1) (1 min of preconcentration) with a precision never worse than +/-7%. The electrode has also been tested on actual samples.