Application of an FR4 printed circuit board for the fabrication of a simple and low cost patterned Cu disk for the determination of paraquat

An FR4 printed circuit board was used to fabricate a patterned Cu disk electrode (p-Cu). It was modified with a Nafion layer (p-Cu/Nafion) and used as a disposable (single-use) sensor for the determination of paraquat. Cyclic voltammetry and linear sweep voltammetry (LSV) were used to obtain the optimal route for paraquat determination using p-Cu/Nafion. The effects of the concentration of Nafion, the type, concentration and pH of supporting electrolyte, and the applied accumulation time and potential on LSV responses of PQ were investigated. Two linear relationships were observed between square wave voltammetry (SWV) responses and the concentration of PQ in the range of 0.5-15 and 25-100 μM, under optimal experimental conditions. The obtained limit of detection (S/N = 3) and limit of quantification (S/N = 10) were 0.29 and 1.0 μM, respectively. The effects of the presence of possible interfering compounds on the SWV responses of PQ were examined and the sensor was applied for the determination of PQ in tomato juice with satisfactory results.