Automated method for determining in vitro cholinesterase inhibition by experimental insecticide candidates

Abstract

using acetylthiocholine iodide (ATChl) as the substrate and 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB) as the color reagent. The substrate and color reagent concentrations were individually varied in order to determine optimum reaction conditions. The ChE assay conditions were found to be 1.5 mM ATChl and 0.38 mM DTNB. The reproducibility of the automated method was evaluated by the simultaneous analysis of 10 aliquots from each of three electric eel ChE solutions containing 247,413, and 1054 units/L ChE. Coefficients of variation (CV) of 5.9-9.0 were obtained for each sample, respectively. Variation between runs was examined by comparing the three electric eel ChE solutions containing 270, 513, and 1247 units/L ChE for 10 different days. A CV of 3.7-7.9% was obtained for each sample, respectively.