Penggunaan teknik voltammetri bagi penentuan pewarna amaranth, tartrazina dan campuran kedua-duanya

Abstract

Hanging mercury dropping electrode (HMDE), carbon paste electrode (CPE), screenprinted carbon electrode combined with Ag/AgCl (SPCE Ag/AgCl), and screenprinted carbon electrode combined with Ag/AgCl and Ag (SPCE Ag/AgCl & Ag) have been applied as working electrodes in determination of amaranth, tartrazine and both dyes mixture. Cyclic voltammetry (CV) studies showed that amaranth, tartrazine and the mixture of both dyes were able to reduce at the surface of HMDE, CPE, SPCE Ag/AgCl and SPCE Ag/AgCl & Ag in acidic pH medium. Parameters optimization using differential pulse voltammetry (DPV) technique showed that the pH of supporting electrolyte, accumulation time, scanning and stirring rate affected the current value (Ip) of the dyes reduction peak produced via these electrodes. Application of SPCE Ag/AgCl with DPV technique in Britton-Robinson (BR) buffer pH 2.31 at non-aerated condition was able to detect reduction peak of amaranth and tartrazine. Chemical pre-treatment of SPCE Ag/AgCl & Ag with 1 M NaHCO3 solution has succeeded producing low limit of detection (LOD) as small as 10-8 M. The usage of HMDE for determination of amaranth, tartrazine and both dyes mixture produced LOD 3.2 x 10-9 M - 11.6 x 10-9 M. The usage of CPE for determination of amaranth, tartrazine and both dyes mixture produced bigger LOD which is 7.5 x 10-9 M - 3 x 10-8 M. The usage of SPCE Ag/AgCl for determination of amaranth and tartrazine in cell produced LOD 7.7 x 10-7 M and 8.1 x 10-7 M respectively. The usage of SPCE Ag/AgCl in beaker produced LOD 10.2 x 10-7 M for amaranth and 7.4 x 10-7 M for tartrazine. The usage of SPCE Ag/AgCl & Ag for determination of amaranth, tartrazine and both dyes mixture produced LOD 1.6 x 10-8 M - 11 x 10-8 M. The repeatability of these electrodes in producing consistent reduction peak current for the dyes is as follows: HMDE > CPE > SPCE Ag/AgCl & Ag > SPCE Ag/AgCl