Several supporting electrolytes namely (NaClO4, Na2SO4, CH3COOH, and HClO4) were tested. Each of the four considered electrolytes was tested working in SWASV. After recording the voltammogram of the blank, the test solutions were spiked with paraquat solution (10−4 mol L−1). The best electrochemical response, measured in terms of the highest analytical signal and improved reproducibility, was obtained in Na2SO4. This means that 0.10 mol L−1 of Na2SO4 was used throughout the experimental program as the supporting electrolyte.