Simultaneous determination of dopamine and ascorbic acid by linear sweep voltammetry along with chemometrics using a glassy carbon electrode

Abstract

A linear sweep voltammetric method has been used for simultaneous determination of mixtures of dopamine and ascorbic acid. It relies on oxidative reaction of dopamine and ascorbic acid at a glassy carbon electrode in a phosphate buffer (pH = 5). The voltammograms of these two compounds overlap strongly, and show non-linear character. Thus, it is difficult to analyze the compounds in their mixtures. In this work, chemometrics methods such as classical least squares (CLS), principal component regression (PCR), partial least squares (PLS) and orthogonal signal correction-partial least squares (OSC-PLS) were applied for the simultaneous determination of these compounds. The linear ranges for dopamine and ascorbic are 3–350 and 5–350 ppm, respectively. The root mean squares error of prediction (RMSEP) are 7.675, 5.938, 5.900, 5.750 for dopamine and 7.533, 6.857, 6.110, 6.031 for ascorbic acid and relative errors of prediction (REP) are 6.695, 5.180, 5.147, 5.016 for dopamine and 5.717, 5.204, 4.637, 4.577 for ascorbic acid by CLS, PCR, PLS and OSC-PLS, respectively. The effects of the different variables on the sensitivity and selectivity of the determination are discussed.