OPTIMIZING ADSORPTION VOLTAMMETRIC TECHNIQUE (AdSV) IN DETERMINING OF AMARANTH ON CARBON PRINTED ELECTRODES. EFFECT OF SURFACTANTS ON SENSITIVITY

Abstract

A simple and sensitive electroanalytical method is optimized by determining amaranth(E123) by AdSVon a screen printed carbon electrode (Dropsens DRP-154). E123 is deposited by adsorption on the electrode surface and the current peak measured by square wave (SWV). The electrode is characterized by cyclic voltammetry (CV) in the presence of cationic surfactant cetylpyridinium bromide (CPB) where E123 is oxidized to 0.62 V by diffusion, increasing near 100% the peak current in the presence of CPB. The experimental variables such as pH, concentration of surfactant (C ) adsorption time (T ) and adsorption CPB ads potential (E ), as well as potential interference, were studied. Under optimal conditions (pH ads -5 -1 2.0; C 1.x 10 molL ; t 90s; E 0.10 V) the peak current is proportional to the CPB ads ads -6 -1 -7 concentration of E123 between 0.10 to 2.0 x 10 molL , with a detection limit of 0.18 x 10 -1 -5 -1 molL . The relative standard deviation for a solution containing 1.0 x 10 molL of E123 was 1.0% for seven equal measures. The method was validated with a water sample doped with E123. Finally the method was applied in the determination of amaranth in samples of sodas.