Dissipation of oxaziclomefone residues from rice, soil, and paddy field water using carbon nanotube-based QuEChERS and HPLC-MS analysis

Abstract

Oxaziclomefone is an organic heterocyclic herbicide widely used in the control of rice weeds but its residues in the environment may pose risks to ecological security. This study established a method for the detection of oxaziclomefone residues in paddy field water, soil, rice plants, rice husks and brown rice using QuEChERS, purification with multi-walled carbon nanotubes, and high-performance liquid chromatography-mass spectrometry, and carried out a field trial. The method showed excellent linearity between oxaziclomefone peak area and concentration in the range 0.01–5 mg/L. The method detection limit were found to be 0.002 mg/kg in water, soil and rice plants and 0.003 mg/kg in brown rice and rice husks. Relative recovery of oxaziclomefone (0.01, 0.1 and 1 mg/kg) from the various matrices was 95.92–108.20% with relative standard deviations of 1.07–9.37%, indicating excellent accuracy and precision. The half-life of oxaziclomefone in rice plants and soil was 3.2–3.5 d and 37.9–41.0 d, respectively (a moderately degraded pesticide). Final oxaziclomefone residue concentrations were significantly below the method limit of quantification in water, plants, rice husks and brown rice, and below the limit of detection in soil, so oxaziclomefone does not pose a risk to the environment or rice consumers. This analytical method has the advantages of simple operation, high sensitivity, quick analysis time and good reproducibility, and is suitable for detection of oxaziclomefone residues in paddy water, paddy soil, rice plants, rice husks, and brown rice.