Using an efficient Al-based MOF in a two-step microextraction procedure for the extraction of pesticides from commercial fruit beverages

To conduct a food safety survey by analysing the pesticide content of various commercial beverages, a dispersive micro-solid-phase extraction procedure was performed using MIL-68 (Al) (a metal-organic framework based on aluminium and 1,4-benzenedicarboxylic acid) as an efficient adsorbent following a preconcentration step by dispersive liquid-liquid microextraction. In the extraction process, the adsorbent was added to an aqueous solution containing the mentioned pesticides and vortexed well. After centrifugation, the analytes loaded on the adsorbent were eluted using 2-propanol. Then, mu L-level of 1,1,2-trichloroethane, as the extraction solvent, was mixed with the obtained 2-propanol phase and injected into deionised water containing dissolved Na2SO4 in which a cloudy solution appeared. One microlitre of the sedimented phase after centrifugation of the cloudy solution was injected into a gas chromatograph equipped with a flame ionisation detector. Satisfactory outcomes such as wide linear ranges (5.95-1000 mu g L-1), acceptable relative standard deviations (4.6-6.9% for intra- (n = 6) and 5.6-7.4% for inter-day (n = 3) precisions), high enrichment factors (228-350), reasonable extraction recoveries (45-70%), satisfactory relative recoveries (82-108%), and low limits of detection (1.15-1.80 mu g L-1) and quantification (3.80-5.95 mu g L-1) were obtained. This research demonstrates the successful application of MIL-68 (Al) for the analysis of some pesticides in fruit beverages. Also, using mg amount of the sorbent and mu L volume of the extraction solvent makes the method precious. Moreover, using a green metal, aluminium, as the central ion of the synthesised metal-organic framework is another beneficial aspect of the research.