Experimental design employed to square wave voltammetry response optimization for the glyphosate determination

The reduction peak current of the derivative N-nitroso of glyphosate herbicide was optimized by experimental design for their determination. The variables involved in the optimization of the square wave voltammetry (SWV) were: voltage step, amplitude, frequency, concentration of the. supporting electrolyte and the area of the mercury drop electrode. A complete 2(5) factorial design was used to evaluate the effects of the variables. From the results obtained by the factorial design was set the three more important factors. These variables were evaluated with a central composite design. The conditions that proportionate the best voltammetric response were: 0.025 volt. 0.125 volt. 70 Hz, 1.25 mol L-1 e 0.60 mm(2) for step voltage, amplitude, frequency, electrolyte concentration and area of the mercury drop, respectively. In these conditions the operational range was from 0.050 up to 100.0 mug mL(-1), the detection and quantification limits were 0.025 and 0.080 mug mL(-1), respectively.