A chemiluminescence procedure for the determination of carbaryl in natural waters using acetylcholinesterase and choline oxidase is described. The flow system designed to implement multicommutation approach controlled by microcomputer comprised five solenoid valves, two columns with immobilized enzymes on controlled pore glass beads and chemiluminometric flow cell. In the best experimental conditions a linear response ranging from 25 to 700 µg L-1 carbaryl was obtained. Water samples were spiked with carbaryl in order to access the accuracy and recoveries between 95 and 101% were obtained for a concentration level ranging from 25 to 100 µg L-1 carbaryl. Detection limit and variation coefficient were estimated as 11 µg L-1 (99.7% confidence level) and 1.3% (n = 20), respectively. Other profitable features such as a sample throughput of 72 determinations per hour, a reagent consumption of 2.1 mg potassium hexacyano ferrate(III) and 0.069 mg luminol per determination were also achieved.
multicommutation; flow analysis; pesticide carbaryl; chemiluminescence; enzymatic reaction
