Schiff Base-UiO66 Composite-based Dispersive Micro Solid-Phase Extraction of Pesticides From Fruit Juices Combined With Dispersive Liquid-Liquid Microextraction Prior to Gas Chromatography-Flame Ionisation Detection

Abstract

A dispersive micro solid-phase extraction method was introduced using a Schiff base-UiO66 nanocomposite as the adsorbent in the extraction of multi-class pesticide residues in pear, cherry, grape, and apricot juices. The extraction procedure was hyphenated with a liquid-phase microextraction procedure, providing a high preconcentration factor and sensitive detection limit. During the extraction procedure, a small amount of the sorbent was added to the sample solution and dispersed via vortexing. Then, the sorbent particles were separated, and the adsorbed analytes were eluted by an appropriate water-miscible organic solvent, which was subsequently used for the preconcentration of the analytes in the following microextraction step. Gas chromatography-flame ionisation detector was utilised as a determination system. All effective factors were evaluated to obtain their optimum values, and then the method was validated. Low limits of detection (0.13–0.27 ng mL⁻¹) and low limits of quantification (0.43–0.89 ng mL⁻¹), acceptable extraction recoveries (59%–71%), high enrichment factors (295–355) and good relative standard deviations (≤10.1%) were the advantages of the method. Fortunately, application of the method on the studied samples showed that the fruit juices were free of the analytes.