Electrochemical impedance spectroscopy determination of glyphosate using a molecularly imprinted chitosan

Abstract The toxicological and environmental damage caused by glyphosate [N-(phosphonomethyl) glycine] (GLY) has been well documented, however, limited efforts have been made to detect it in the environment. In response to that, we report the development of an extremely sensitive electrochemical sensor for GLY detection in water. This novel concept of glyphosate sensor is based on molecularly imprinted polymer (MIPs) made of chitosan (CS) biopolymer electrochemically deposited onto a gold microelectrode. Electrochemical Impedance Spectroscopy (EIS) was used for the label free detection of GLY in a linear range from 0.31 pg/ml to 50 ng/ml with a low detection limit of 0.001 pg/ml (S/N = 3). Moreover, the success of the MIPs layer affinity to GLY was confirmed through detection of GLY with non-imprinted CS (NIPs); a good imprinting factor of 14.5 was obtained. The selectivity of the MIPs was verified with the detection of different pesticides as interferences. Very high selectivity factors (SF) were obtained: 7.9 for glyfosinate, 43.5 for chlorpyrifos and 14.5 for phosmet.