DPV Determination of Residual Amount of Paraquat in Soil, Water and Mouselet Plasma with HDNA/NG/GCE as Working Electrode

To prepare the modified electrode of HDNA/NG/GCE, NG/GCE was prepared preliminarily by applying 5.0 μL of 1.0 g·L^-1 NG solution onto the surface of GCE, which was then dried in air. And afterwards, 10.0 μL of 5.0 μmol·L^-1 HDNA solution was applied onto the surface of NG/GCE, which was incubated in a refrigerator at 4℃ for 2 h. TEM and SEM were applied to characterize specificity of NG and electrochemical methods of CV and DPV were applied to study the electrochemical behavior of paraquat (PQ) at the modified electrode as working electrode. It was found that ① in a 0.1 mol·L^-1 PBS of pH 8.0, a significant reduction peak given by PQ was observed at the potential of -0.523 V; ② value of reduction peak current of PQ obtained at the modified electrode (21.08 μA) was greater than that obtained at the GCE (2.102 μA); and ③ linear relationship was found between values of reduction peak current and the corresponding concentration of PQ in the range from 6.0×10^-8mol·L^-1 to 4.0×10^-5mol·L^-1, with detection limit (3s/k) of 1.6×10^-8mol·L^-1. The proposed method was applied to the determination of residual amount of PQ in substantial samples of soil, water and mouselet plasma. Tests for recovery were made by standard addition method using soil samples as matrixes, values of recovery found were in the range from 81.7% to 107%.