Metal-organic frameworks as promising solid-phase sorbents for the isolation of third-generation synthetic cannabinoids in biological samples.

In this work, metal-organic frameworks (MOFs) were used for the first time as solid-phase extraction (SPE) sorbents for the isolation of synthetic cannabinoids (SCs) from oral fluids and subsequently quantified by LC-fluorescence detection (FLD). In this context, different MOF families were synthesized and tested under SPE mode. UiO-66 was the family selected, being the amino functionalized (NH2-UiO-66) the best candidate in terms of extraction performance. After the method optimization, several analytical parameters of interest were obtained, reaching limits of detection (LODs) as low as 0.6-0.8 μg L-1 and precision values (expressed as RSD) lower than 10.6%. The developed method was successfully applied to the determination of 8 SCs in different oral fluids at three spiked levels with recoveries between 67 and 114%. This method claims to be a real alternative for screening purposes, being a cost-effective procedure due to the price of the sorbent (<0.5 €/cartridge) and its recyclability (up to 12 uses), among others good features.