Determination of Fluazinam in Vegetables and Fruits Using a Modified QuEChERS Method and Liquid Chromatography-Tandem Mass Spectrometry

A modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) sample preparation was developed for the determination of fluazinam in six vegetables (cabbage, cucumber, tomato, pak choi, spinach, and zucchini) and four fruits (apple, grape, orange, and strawberry), followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Samples were purified by dispersive solid-phase extraction (d-SPE) using hydroxylated multi-walled carbon nanotubes (MWCNTs-OH) as the absorbent. Method validation yielded satisfactory results in terms of the linearity (R 2 > 0.99) over a range of 1–500 μg L −1 , fortified recovery (81–115%) at three spiked levels, precision (RSDs ≤12%), and sensitivity (limit of quantification (LOQ) of 5 ng g −1 ). The established method was further applied to determine fluazinam in 120 vegetable samples and 80 fruit samples collected from local markets. The fluazinam residues in most of the samples were below the LOQ, except for two strawberry samples containing 97 and 135 ng g −1 . Therefore, the present method was proven to be a reliable and convenient analytical method for monitoring fluazinam residues in vegetable and fruit matrices.