The application of NiCo-LDH for the extraction and preconcentration of some widely used pesticides from strawberry juice samples prior to their determination by gas chromatography

This study presents a method combining dispersive micro-solid phase extraction with dispersive liquid-liquid microextraction for the extraction of pesticide residues from strawberry juice samples. A ZIF-67-derived nickel-cobalt-layered double hydroxide was employed as the sorbent. The method involved the adsorption of analytes onto the sorbent surface by vortexing in a solution containing dissolved sodium chloride, followed by centrifugation to isolate the sorbent particles. The pesticides were then desorbed from the sorbent using a mL-volume of methanol. A µL-volume of 1,2-dibromoethane was added to this methanolic extract, and the resulting mixture was rapidly injected into deionized water. The cloudy solution was formed and underwent centrifugation, and an aliquot of the settled extractant was injected into the gas chromatograph equipped with a flame ionization detector. The method demonstrated favorable linearity (r 2 ≥0.990), high enrichment factors (160-455), acceptable extraction recoveries ranging from 32 to 91%, and low limits of quantification (1.6-31 µg L -1 ) and detection (0.5-9.3 µg L ˗1 ). The novelty of this study lies in the first-time utilization of a MOF-derived NiCo-LDH for pesticides determination, offering enhanced adsorption capacity, selectivity, and stability over traditional sorbents. This approach demonstrated minimal matrix effect in complex strawberry juice samples and offered a simple, efficient, and cost-effective option for pesticides residue analysis.