Amperometric biosensors based on nafion coated screen-printed electrodes for the determination of cholinesterase inhibitors.

Screen-printed electrodes coated with the nafion layer have been investigated for cholinesterase biosensor design. The butyrylcholinesterase (ChE) from horse serum was immobilised onto the nafion layer by cross-linking with glutaraldehyde vapours. The biosensors obtained showed better long-term stability and lower working potential in comparison to those obtained with no nafion coating. The sensitivity of a biosensor toward organophosphate pesticides is not affected by the nafion coating. The detection limits were found to be 3.5x10(-7) M for trichlorfon and 1.5x10(-7) M for coumaphos.