Development of a portable electroanalytical methodology for determination of sulfite in wine using screen-printed carbon electrodes modified with carbon nanotubes

Abstract

This study describes the development of an electroanalytical methodology applying square wave voltammetry (SWV) to quantify sulfite in wine using a portable system associated with screen-printed carbon electrodes modified with carboxyl functionalized multi-walled carbon nanotubes (SPCE MWCNT-COOH). SWV parameters were optimized using the design of experiments in 0.100 mol L−1 phosphate buffer at pH 4.00 as supporting electrolyte. The sulfite agents showed an oxidation peak around 0.700 V, which corresponds to the species HSO3−, and values of the limit of quantitation and detection of 4.99 × 10−5 and 1.65 × 10−5 mol L−1, respectively, in the linear range of 5.00 × 10−6 to 8.00 × 10−4 mol L−1, and R2 equal to 0.997. The method did not show interference between common molecules found in wine. Furthermore, wine samples were analyzed by the proposed technique and compared with the Brazilian official method (iodometric titration). There was no significant difference between the sulfite concentrations obtained in both procedures. These results show that the proposed methodology is promising for monitoring sulfite agents, employing a low amount of sample per analysis, and the possibility of applying the sulfite determination in loco.