Determination of anticholinesterase activity for pesticides monitoring using a thiocholine sensor

An acetylthiocholine sensor based on a disposable screen-printed carbon ele ctrode has been assembled for measuring organophosphorus and carbamate pest icides in river water samples through the degree of inhibition of the enzym e acetylcholinesterase (AChE). The carbon working electrode surface was mod ified by deposition of a mediator, tetracyanoquinodimethane (TCNQ), and Naf ion. Acetylcholinesterase catalyses the cleavage of acetylthiocholine to th iocholine, which is measured by differential pulse voltammetry and directly related to the enzyme activity. The scan speed, the pulse amplitude of the differential pulse voltammetry and several parameters in the procedure wer e optimised, An inhibition calibration curve was obtained using carbofuran. The method was also applied to water samples, showing its suitability as a rapid screening assay (15 min per test) for anticholinesterase activity de tection.