Residue analysis of orthosulfamuron herbicide in fatty rice using liquid chromatography–tandem mass spectrometry

In the present study, orthosulfamuron residues were extracted from fatty (unpolished) rice and rice straw using a modified QuEChERS method and analyzed using liquid chromatography–tandem mass spectrometry. The matrix-matched calibration was linear over the concentration ranges of 0.01–2.0 mg/kg with determination coefficient (R(2)) ⩾ 0.997. The recovery rates at two fortification levels (0.1 and 0.5 mg/kg) were satisfactory and ranged between 88.1% and 100.6%, with relative standard deviation (RSD) <8%. The limit of quantitation, 0.03 mg/kg, was lower than the maximum residue limit, 0.05 mg/kg, set by the Ministry of Food and Drug Safety in the Republic of Korea. The developed method was applied successfully to field samples harvested at 116 days and none of the samples were positive for the residue.