APPLICATION OF THE BISMUTH FILM ELECTRODE FOR THE DETERMINATION OF SELENIUM IN VITAMINIC COMPLEX BY SQUARE WAVE VOLTAMMETRY

This work was developed an analytical methodology for determination of selenium in samples of vitaminic complex using the square wave voltammetry (SWV). The analysis were performed with a copper electrode modified with bismuth film deposited by applying a potential of -400 mV for 60 seconds in a solution containing HCl 0.2 mol L-1, 20 g L-1 and 500 µg L-1 of Bi(III). The variables: time and conditioning potential were optimized by SWV for the formation of the bismuth film, after that, the variables that affect the analytical sensitivity for the reduction of Se (IV): frequency, increment and high of pulse were also optimized. The linearity of the method ranged from 90 – 1180 µg L-1. Limit of detection of 26,4 µg L-1, quantification limit of 87,9 µg L-1. Analytical frequency of 30 samples/hour. The method showed excellent precision, calculated as the relative standard deviation (RSD%) (n = 5) using spiked solution of 150 µg L-1. The concentration of selenium found in the sample of the vitaminic complex was 24 µg/tablet. A study of recovery was performed resulting in 92%.