Non-aqueous flow-injection determination of atrazine by inhibition of immobilized tyrosinase

A method for the extraction and flow-injection enzymatic determination of trace amounts of atrazine in corn is described. It is based on the inhibition of the tyrosinase-catalysed oxidation of catechol in chloroform and spectrophotometric detection at 380 nm of the o-quinone formed. The calibration graphs were linear from 1.0–7.0 mg l−1 and the relative standard deviation (n=4) was 7.0%. Interference from simazine was not observed at levels up to 8 mg l−1. Hydroxyatrazine, 2,4-dichlorophenoxyacetic acid, 2,4-dichlorophenol and zinc-N,N′-dimethyldithiocarbamate also did not show interference up to 10 mg l−1. Recovery from spiked corn samples was 98% and extensive clean-up was not necessary.