Correlation between Electrochemical Impedance and Spectroscopic Measurements in Adsorbing Paraquat on Silver: Application in Underground Water Samples

The electrochemical impedance spectroscopy (EIS) has been used to study the interaction between paraquat and carbon modified by silver (AgCPE) and silver particles‐impregnated natural phosphate (Ag/NPhCPE). This study was developed using spectrophotometry (UVVis) and infrared spectroscopy. The resulting interaction was controlled by adsorption at lower concentration (≤1.0×10 −5 mol L −1 ) and by diffusion in the opposite case. Both electrodes are used to determining paraquat with a low detection limit (<1.0×10 −12 mol L −1 ). The precision expressed as relative standard deviation RSD for the concentration level 1.0×10 −5 mol L −1 of paraquat, (n=8) were 0.93 % and 1.1 % for Ag/NPhCPE and AgCPE respectively.