Nicosulfuron residues in agricultural soil

Abstract

Nicosulfuron is one of the most applicable sulfonylurea herbicides for control of annual and perennial weeds in maize. Its residues can persist in soil at phytotoxic concentrations and affect sensitive succeeding crops more than one season after treatment. Therefore, monitoring the trace levels of this herbicide in soil is a challenging task and demands highly efficient, selective, and sensitive analytical technique. This study was conducted for the purpose of investigating nicosulfuron residues presence in soil. Soil samples were collected before crop seeding, from two soil layers, surface (0-30 cm) and sub-surface (30-60 cm). Nicosulfuron determination and quantification were performed by HPLC with diode-array detection, using isocratic elution of mobile phase. Nicosulfuron was extracted from the soil sample with mixture of phosphate buffer (pH 7.4)/methanal (80/20, v/v) solution with clean-up on C18 extraction cartridge. The linearity of detector response showed that the calibration curves were linear with correlation coefficient (R’) of 0.999. Relative standard deviations (RSD) of the retention times and of the peak areas were 0.79 and 1.06%, respectively and fulfilled the criteria of chromatographic measurements. The accuracy of the defined method was confirmed by the good results of recovery assay, while achieved limit of detection (LOD) and limit of quantification (LOO) for nicosulturon in soil were in accordance with SANCO/825/00 (SANCO, 2010). The proposed analytical procedure was applied for monitoring of nicosulfuron herbicide in soil. Average values of nicosulfuron residues in soil samples from surface and sub-surface horizon were 0.05 mg/kg.