A differential-pulse adsorptive stripping voltammetric (DPAdSV) procedure with the use of pulsed potential accumulation and carboxyl functionalized multiwalled carbon nanotubes modified screen-printed carbon electrode (SPCE/MWCNTs-COOH) was delineated for simultaneous analysis of paracetamol (PA) and diclofenac (DF). The use of carboxyl functionalized MWCNTs and pulsed potential accumulation improves the analytical signals of PA and DF, and minimizes interferences from surfactants. After optimization of analytical conditions for this sensor, the peak currents of the two compounds were found to increase linearly with the increase in their concentration (5.0 × 10-9-5.0 × 10-6 mol L-1 with a detection limit of 1.4 × 10-9 mol L-1 for PA, and 1.0 × 10-10-2.0 × 10-8 mol L-1 with a detection limit of 3.0 × 10-11 mol L-1 for DF). For the first time, the electrochemical sensor allows simultaneous determination of PA and DF at concentrations of 24.3 ± 0.5 nmol L-1 and 3.7 ± 0.7 nmol L-1, respectively, in wastewater samples purified in a sewage treatment plant.
Keywords: carboxyl functionalized multiwalled carbon nanotubes modified screen-printed carbon electrode; direct analysis; environmental water and sewage samples; liquid chromatography; paracetamol and diclofenac; pulsed potential accumulation, voltammetry.