Comparison of reversed-polarity capillary electrophoresis and adsorptive stripping voltammetry for the detection and determination of reactive textile dyes

Abstract

Reversed-polarity capillary electrophoresis (CE) and adsorptive stripping voltammetry (AdSV) using a hanging mercury drop electrode are compared for the separation and determination of six reactive textile dyes. Only four of the six starting dyes could be separated in the reversed-polarity mode of CE. No change in pH, temperature, run buffer, acetonitrile concentration of surfactant brought about separation of all six dyes. Optimum separation of the hydrolysed dyes was achieved using an electrolyte of 0.05 mol dm–3 citric acid (pH 3.25) with 10% acetonitrile. Stacking of the dyes was performed using a 0.05 mol dm–3 citric acid buffer (pH 2.23), containing 0.006 mol dm–3 diethylenetriamine. Electrokinetic injections were investigated using 0.05 mol dm–3 citric acid (pH 2.23) buffer with an injection time of 30 s at a voltage of 10 kV. AdSV studies were carried out using a 0.2 mol dm–3 acetate–acetic acid buffer (pH 4.5) and a 5 min accumulation time at the mercury electrode. The correlation coefficients of the calibration graphs and limits of detection for both techniques are also compared.