Biosensor for Field Monitoring of Pesticides in Water

This Phase II research project will develop a field-portable, amperometric biosensor for monitoring organophosphorus (OP) and carbamate insecticides in water. The miniaturized biosensor will use a modified, screen-printed microelectrode with high sensitivity and low limit of detection for OP and carbamate pesticides. This biosensor will be selective for OPs and carbamates. The enzyme used to generate the amperometrically detectable species is selectively inhibited by these insecticides, but not by other common classes of agricultural chemicals, such as triazine herbicides. The device uses a single-use, disposable monitoring chip, because some of the active pesticides (e.g., the OPs) irreversibly inhibit enzyme activity. Carbamate inhibition is more reversible, but the device, in this case, was evaluated for a single use mode. During Phase I, Eltron Research, Inc., demonstrated effective enzyme inhibition by two representative pesticides, aldicarb (carbamate) and methyl parathion, which is an OP insecticide. Aldicarb was detected with a detection limit of 11 ppb, while methyl parathion’s detection limit was 18 ppb. This performance is compatible with existing maximum contaminant limits set by the U.S. Environmental Protection Agency. Biosensors that can be taken into the field will enable cost efficient environmental monitoring of water supplies. Pesticide contamination could represent a growing and currently underregulated threat because these toxic chemicals are used extensively in agriculture. Potential pollution sources include rainwater runoff of mobile pesticides and spray drift during aerial applications. The proposed sensor will offer a cost-reduction strategy for pesticide screening. Prior field screening of samples could contain costs associated with laboratory testing by providing a means to screen out negative, or pesticide-free, samples.