Aptamer-functionalized stir bar sorptive extraction coupled with gas chromatography–mass spectrometry for selective enrichment and determination of polychlorinated biphenyls in fish samples

•Aptamer-functionalized SBSE coating was applied to selectively detect PCBs.•MOF-5 was used as the substrate of SBSE coating to increase adsorption capacity.•The Apt-SBSE/GC–MS method to determine ng kg−1 PCBs in fish samples.•The MOF-5 was prepared by controlled electro-deposition on the stainless steel wire.

In this paper, a novel aptamer-functionalized stir bar sorptive extraction (SBSE) was developed for selective enrichment of the low abundance polychlorinated biphenyls (PCBs) from fish samples. This approach was based on the immobilization of aptamer which could recognize 2,3′,5,5′-tetrachlorobiphenyl (PCB72) and 2′,3′,4′,5,5′-pentachlorobiphenyl (PCB106) on one kind of metal-organic frameworks (Zn4O(BDC)3, MOF-5). MOF-5 as a substrate was prepared by potential-controlled cathodic electrodeposition on stainless steel. This aptamer-functionalized stir bar sorptive extraction (Apt-MOF SBSE) fiber could be facile synthesized in one-step. PCB72 and PCB106 were employed as target analytes for selective extraction by the developed method. The adsorbed targets could be desorbed easily in pH 3.0 100 mM glycine–HCl buffers and then extracted by the methylene chloride. Afterwards, the detection was carried out with gas chromatography–tandem mass spectrometry (GC–MS). The Apt-MOF SBSE pretreatment coupled with GC–MS exhibited high selectivity, good binding capacity, stability and reproducibility for the detection of PCBs. It provided a linear range of 0.02–250 ng mL−1 with a good coefficient of determination (R2=0.9991−0.9996) and the detection limit was 0.003–0.004 ng mL−1. More importantly, the method was successfully utilized for the determination of PCBs in fish samples with good enrichment factor (1930-2304). Therefore, this new SBSE coating opens up the possibility of selective enrichment of a given target PCBs from complex fish samples.

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