SOLID-PHASE EXTRACTION FOLLOWED BY HPLC/DAD FOR DETERMINATION OF SULFONYLUREA HERBICIDE IN SOIL PUBLISHEDSanja LAZIĆ, Dragana ŠUNJKA
Abstract. Sulfonylurea herbicides are widely used for control for most broad-leaves weeds and common grasses in agricultural crops in quite low application rate (less than 100 g/ha). Their persistence in the soil environment is mainly dependent on several site specific factors, such as rainfall, soil properties (especially pH and organic matter), climate and combination of factors. The fate of sulfonylurea herbicides in soil ranges from few weeks to three or more years. Generally, sulfonylurea herbicides represent potential environment pollutants in soil and water. One of the most applicable SU herbicide is nicosulfuron (1-(4.6-dimethoxypyrimidin-2-yl)-3-(3-dimethylcarbamoyl-2-pyridylsulfonyl) urea). In extreme weather conditions, nicosulfuron residue in soil can influence phytotoxicity symptoms in some sensitive crops, such as sugar beet or soybean. In order to develop simple and rapid, but enough sensitive method for determination of nicosulfuron residues in soil sample, this study was conducted. Method validation was performed by analyzing spiked uncontaminated soil samples (10 g) with nicosulfuron at three levels 2.5, 5.0 and 7.5 μg/ml. Extraction was done with phosphate buffer pH 7.4/methanol (80/20, v/v) solution. The mixture was shaken for 1 min using Vortex and liquid and solid phases were separated by centrifugation at 3000 rpm for 5 min. The extraction process was repeated two times, followed by cleaning up on C18 cartridges. Analysis was carried out using an HPLC-UV diode array detection system (Agilent 1100, USA), with an Agilent Zorbax Eclipse C18 column (50 mm × 4.6 mm, 1.8 μm) and mobile phase consisting of ultrapure water pH 2.5 with H3PO4 and acetonitrile (70/30, v/v). Presence of nicosulfuron was confirmed by overlapping spectra (240 nm) from standard solution and from soil sample spiked with nicosulfuron. The accuracy of the defined method was confirmed by the good results of recovery assay (89%). The limit of detection and limit of quantiﬁcation were found to be 0.01 mg/kg and 0.05 mg/kg, respectively. Described method is applicable for analysis of this herbicide in real soil samples.
sulfonylurea herbicide, nicosulfuron, residue, soil, HPLC