Selective dispersive solid phase extraction-chromatography tandem mass spectrometry based on aptamer-functionalized UiO-66-NH2 for determination of polychlorinated biphenyls

• Aptamer-functionalized UiO-66-NH2 was applied to selectively extract PCBs.
• UiO-66-NH2 used as the substrate to increase adsorption capacity.
• Fe3O4@PDA@UiO-66-NH2was prepared without seeding by using PDA as covalent linker.

In this paper, a novel dispersive solid phase extraction (dSPE) adsorbent based on aptamer-functionalized magnetic metal-organic framework material was developed for selective enrichment of the trace polychlorinated biphenyls (PCBs) from soil sample. Firstly, we developed a simple, versatile synthetic strategy to prepare highly reproducible magnetic amino-functionalized UiO-66 (Fe3O4@PDA@UiO-66-NH2) by using polydopamine (PDA) as covalent linker. Then amino-functionalized aptamers which can recognize 2,3′,5,5′-tetrachlorobiphenyl (PCB72), 2′,3′,4′,5,5′-pentachlorobiphenyl (PCB106) were covalent immobilized on UiO-66-NH2 through coupling reagent of glutaraldehyde. Aptamer-functionalized adsorbent (Fe3O4@PDA@UiO-66-Apt) can specifically capture PCBs from complex matrix with high adsorption capacity based on the specific affinity of aptamer towards target. Moreover, the adsorbent can be easily isolated from the solution through magnetic separation after extraction. Afterwards, the detection was carried out with gas chromatography tandem mass spectrometry (GC–MS). The selective dSPE pretreatment coupled with GC–MS possessed high selectivity, good binding capacity, stability, repeatability and reproducibility for the extraction of PCBs. Furthermore, the adsorbent possessed good mechanical stability which can be applied in replicate at least for 60 extraction cycles with recovery over 80%. It provided a linear range of 0.02–400 ng mL−1 with a good correlation coefficient (R2 = 0.9994–0.9996), and the limit of detection was found to be 0.010–0.015 ng mL−1. The method was successfully utilized for the determination of PCBs in soil samples.