Simultaneously detecting ethyl carbamate and its precursors in rice wine based on a pH-responsive electrochemical impedance sensor.

Intensive efforts have been made to diminish ethyl carbamate in fermentation products. The presented research demonstrated an approach to simultaneously detecting ethyl carbamate and its precursors including urea, citrulline and arginine with nano Mn(Ⅱ)O modified composite working electrode via electrochemical impedance spectroscopy. Adjusting sample solutions at certain pH value leads the differentiated priority of protonation from nitrogen group in the ethyl carbamate (EC) and its precursors. Molecular recognition was achieved through attractive electrostatic interaction due to the negatively charged Mn(Ⅱ)O nanocrystal on the working electrode surface in aqueous sample solutions. Deconvolution and principle component analysis were applied to differentiate the specific scanning frequency for each analyte. The detection limits of EC, citrulline, urea and arginine are 0.8 ng L, 1.57 ng L, 0.54 ng L and 1.56 ng L, respectively. The developed electrochemical sensor provides a sensitive and selective approach superior to the current reported label-free methodologies and offering a solution for ethyl carbamates in real time process control.