Organophosphate insecticides are the insecticides most often involved in serious human poisoning.
Several colorimetric procedures have been devised. In this investigation m-nitrophenol method has been used. The difference in the absorbancy of color produced gives a measure of enzyme activity. Results are expressed as the number of acetyl choline hydrolysis per hour per ml serum. The result obtained in this study showed that PchE activity level reached to normal levels within 24 hours.