Determination of propoxur in environmental samples by automated solid-phase extraction followed by flow-injection analysis with tris(2,2′-bipyridyl)ruthenium(II) chemiluminescence detection

Abstract

A sensitive method for the analysis of propoxur in environmental samples has been developed. It involves an automated solid-phase extraction (SPE) procedure using a Gilson Aspec XLi and flow-injection analysis (FI) with chemiluminescence (CL) detection. The FI–CL system relies on the photolysis of propoxur by irradiation using a low-pressure mercury lamp (main spectral line 254 nm). The resultant methylamine is subsequently detected by CL using tris(2,2′-bipyridyl)ruthenium(III), which is on-line generated by photo-oxidation of the ruthenium(II) complex in the presence of peroxydisulfate. The linear concentration range of application was 0.05–5 μg mL −1 of propoxur, with a detection limit of 5 ng mL −1. The repeatability was 0.82% expressed as relative standard deviation ( n = 10) and the reproducibility, studied on 5 consecutive days, was 2.1%. The sample throughput was 160 injection per hour. Propoxur residues below ng mL −1 levels could be determined in environmental water samples when an SPE preconcentration device was coupled on-line with the FI system. This SPE–FI–CL arrangement provides a detection limit as low as 5 ng L −1 using only 500 mL of sample. In the analysis of fruits and vegetables, the detection limit was about 10 μg kg −1.