Magnetic metal-organic frameworks coated stir bar sorptive extraction coupled with GC–MS for determination of polychlorinated biphenyls in fish samples

Abstract

In this work, several kinds of the metal-organic framework (MOF) were evaluated the adsorption performance to PCB. Finally, MOF-5(Fe) was introduced in stir bar sorptive extraction (SBSE) as the adsorbent to extract six polychlorinated biphenyls (PCBs). Nd–Fe–B permanent magnet was employed as stir bar, which was then coated with Fe3O4-MOF-5(Fe) composite magnetic material, which was prepared by solvothermal method. The stir bar was then employed to extract and enrich six indicator PCBs (2,2′,5,5′-tetrachlorobiphenyl, 2,2′,4,5,5′-pentachlorobiphenyl, 2,2′,3,4,4′,5-hexachlorobiphenyl, 2,3,4,4,5-pentachlorobiphenyl, 2,2′,4,4′,5,5′-hexachlorobiphenyl, 2,2′,3,4,4′,5,5′-heptachlorobiphenyl) under stirring, then eluted by n-hexane under ultrasound. Its saturated adsorption amount was found to be 17.0–17.8mgg−1 and only 30min were needed to reach adsorption equilibrium. The MOF-stir bar can be reused for 60 times with the recovery above 80%, which exhibited good stability. Under the optimal experimental conditions, MOF-5(Fe) based SBSE was coupled with GC–MS for detecting six PCBs. The limits of detection (S/N=3) of the developed method were 0.061–0.096ngg−1, with enrichment factors of 50–100 fold. And the linear ranges were 0.01–500μgL−1. The new method was successfully applied to assess PCBs in fish samples with satisfactory recovery ranging from 94.3% to 97.5%.