A metal–organic framework, MIL-101(Cr), was used to adsorb sulfamethoxazole (SMZ) in water and activated persulfate (PS) oxidation was investigated to regenerate SMZ-saturated MIL-101(Cr).
A modified QuEChERS method was optimized to determine 66 pesticide residues in spinach using gas chromatography with mass spectrometric detection in selected-ion monitoring mode. Graphitized carbon black (GCB) at different levels (0, 5, 10, 15, 20, and 25 mg) was used to adsorb the pigments in spinach extracts. Best recoveries with less colored extract samples for all pesticides analyzed were obtained in the presence of 10 mg GCB. Under the optimized condition, analyses of spiked samples were performed at 3 different levels. Correlation coefficients, R2, in the linear range tests were better than 0.99. Average recoveries ranged from 66 to 104, with the relative standard deviation below 16. The limits of quantitation ranged from 50 to 250 g/kg.
A simple confirmatory method for the determination of metaflumizone in cabbage tissues and soil samples using ultra-performance liquid chromatography-ESI/MS/MS is presented. Metaflumizone residues in cabbage and soils were extracted with acetonitrile and an aliquot was cleaned up with primary and secondary amine. Two precursor product ion transitions for metaflumizone were measured and evaluated to provide the maximum degree of confidence in results. Under ESI negative conditions, quantitation was achieved by monitoring the fragment m/z 5 302 and qualitative fragment m/z 5 116.5 while also collecting their parent ion m/z 5 505.5. Average recoveries for cabbage and soil at four different levels (0.01, 0.05, 1 and 5 mg/kg) ranged from 77.6 to 87.9% with RSD of 3.5-7.9% and RSD R of 4.5-7.1%. The coefficients of determination of R 2 X 0.9991 were achieved for metaflumizone calibration curves from 0.01 to 5.0 mg/mL. The metaflumizone LODs in cabbage and soil were determined to be both 0.001 mg/kg with a LOQ of 0.004 mg/kg. This method was able to demonstrate quantitative recoveries and provide confirmatory data for the identification of metaflumizone residues in cabbage tissues and the surrounding soils following commercial application.
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