Qualitative Detection of Residual Pesticides on Cotton Fibers

A method based on the measurement of bio-electrical signals caused by enzymatic inhibition of acetylcholinesterase (AChE) has been performed in this study for the detection of organophosphorous and carbamate pesticides being the strong inhibitor of AChE and prevents its normal function of the rapid removal of acetylcholine (ACh). Biosensor Toxicity Analyzer (BTA) equipped with electrochemical sensors was used for the testing and enzyme activity was determined by acetylthiocholine chloride (ATCCl) as enzyme substrate. The monitoring of changes in bio-electrical signals caused by the interaction of biological substances and residues were evaluated. Two samples of cotton Giza 86 from Egypt of the crop 2009/2010 were analyzed. One of them was the classical conventional cotton and the other was organic cotton which was produced without utilizing the synthetic pesticides. Cryogenic homogenization was carried out for sample pretreatment and Soxhlet extraction method (SOX) was used with two different solvents; hexane and dichloromethane for both of the samples, respectively. The resulted extracts were concentrated and then injected in the BTA for the measurement of bio-electrical signals. The method described shows reasonable results and can successfully be utilized for the detection of residual pesticides on different types of cotton.