A Modified and Validated QuEChERS Method for Agrochemical Residue Analysis in Nicotiana tabacum Leaf Using Green Reagents (Ionic Liquids and Nanocarbons)
A modified QuEChERS multi-residue method using green reagents (Nicotiana tabacum waste stems-generated nanocarbons and ionic liquids) was optimized and validated for N. tabacum samples. Instrumental analysis was carried out using liquid chromatography tandem mass spectrometer. 1-Benzyl-3-methylimidazolium chloride was established to be the ideal ionic liquid to replace the traditional organic solvent and 10 ml of this was the optimum volume. The ideal nanocarbon weight was found to be 20 mg. The limit of detection ranged from 0.006 μgg-1 to 0.025 μgg-1 and limit of quantification ranged from 0.01 μgg-1 to 0.05 μgg-1 with relative standard deviation ranging from 12.55% to 19.98% for the seven analytes studied. The recoveries for the analytes ranged from 69.9% - 120.1% with RSD of less than 18%. The expanded uncertainty at 95% confidence using a coverage factor (k = 2) was found to be 5.10%. The validated method was successfully applied for the determination of methamidophos and monocrotophos in real N. tabacum samples from selected tobacco-growing regions in Zimbabwe.