Development of an EnFET for the detection of organophosphorous and carbamate insecticides

A biosensor for the detection of insecticides based on an ion-sensitive field-effect transistor (ISFET) was developed. The resulting device combines the simplicity of potentiometric sensors and the use of associated electronic systems as powerful tools for the acquisition and the processing of data. The enzyme acetylcholinesterase (AChE) was entrapped in a membrane placed on the gate of the ISFET forming an enzyme field-effect transistor (EnFET). The biosensor is applied to the determination of pesticides in spiked real samples. Organophosphorous and carbamate insecticides were measured with a detection limit of 10(-8) mol L(-1). The measurement is based on the production of hydrogen ions due to the hydrolysis of acetylthiocholine by the enzyme. The resulting local pH change is picked up by the underlying pH-sensitive ISFET and transduced as potential variations. The preparation of the membrane is simple and reproducible. The analysis in spiked real samples was performed in tap water and showed detection limits comparable to those obtained by other researchers.