Supramolecular solvent microextraction of phenylurea herbicides from environmental samples

An efficient microextraction method was developed for extraction and determination of phenylurea herbicides (monuron, linuron and isoproturon) in water and rice samples followed by analysis with high performance liquid chromatography (HPLC). The proposed method based on microextraction of herbicides in supramolecular solvent (SUPRAs, 400 mg decanoic acid; 15% THF) for 1.0 min of centrifugation. Factors affecting the extraction efficiency of herbicides like pH, amount of decanoic acid (DeA), volume of tetrahydrofuran (THF), composition of SUPRA, centrifugation time and sample amount were studied. Limit of detection (LOD) and quantification (LOQ) were 30 ngmL(-1) and 10 ngmL(-1) for monuron, 10 ngmL(-1) and 30 ngmL(-1) for linuron, 30 ngmL(-1) and 100 ngmL(-1) for isoproturon with linear range of 0.3-20 (10(3)) ngmL(-1). The inter-day RSD values were 2.5-3.7%, 4.2-5.5% and 5.2-7.2, while for intra-day the obtained RSD values were 3.2-4.1%, 4.3-5.2% and 5.2-6.5% for 5,10, 15 (10(3) ngmL(-1)), respectively. The proposed method has been applied successfully to the spiked water and rice samples and recoveries in the range of 91.1-99.0 % for tape water, 82.5-94.0% for canal water and 80.0-85.5% for rice samples were obtained.