Nickel-Cobalt-Layered Double Hydroxide and Carbon Composite for Monitoring the Plasticizers Migrated Into Hot Tea Drinks

In this study, a metal-organic framework-derived layered double hydroxide named nickel-cobalt-layered double hydroxide was synthesized from ZIF-67 and mixed with activated carbon to prepare a suitable sorbent for dispersive micro solid phase extraction. It was used to extract plasticizers from the tea infusions. To develop the method, the composite adsorbed the analytes through vortexing in a solution containing dissolved NaCl. Subsequently, to separate the sorbent particles, centrifugation was used. A desorption solvent composed of methanol and 3-picoline was utilized via vortexing to release the plasticizers from the sorbent. Subsequently, 1,2-dibromoethane at the µL level was eked into the desorption solvent, and the resulting mixture was injected into an aqueous solution containing dissolved NaCl. The obtained cloudy solution was subjected to centrifugation, and an aliquot of the settled extractant was injected into a gas chromatograph equipped with a flame ionization detector. Favorable extraction recoveries (ranging from 36% to 89%), high enrichment factors (180-445), low limits of detection (0.65-4.01 µg L^-1), good intra- (2.64%-3.82%) and inter-day (3.06%-6.95%) relative standard deviations, and wide linear ranges of the calibration curves were recorded. Applying an anti-solvent-oriented workup section to increase the yield of ZIF-67, production of the composite, and its application in sample preparation for the first time were novel aspects of the research.