One-step synthesis of mercapto modified hierarchical porous polymer capillary monolithic column for chip based array microextraction of mercury species in cells

Exploitation of efficient adsorbent for analyzing mercury species in complex biological samples is still a big challenge. Herein, a MIL-101 covalently bonded and mercapto functionalized capillary monolithic column was prepared by one-step strategy involving simultaneous initiation of thiol-ene click reaction and radical polymerization. It showed improved specific surface area, hierarchical porous structure, rich sulfhydryl groups and high adsorption capacity for mercury species. It was embedded in the microchannel of microfluidic chip for chipbased array monolithic capillary microextraction (CMCME) of mercury species in cells. Methylmercury (MeHg+) and inorganic Hg (Hg2+) could be simultaneously retained on the prepared column and sequentially eluted; both species could also be simultaneously eluted with 4% thiourea in 0.5 mol L-1 HNO3 solution. Based on it, CMCME was combined with two online detection modes separately, direct inductively coupled plasma mass spectrometry (ICP-MS) detection and high-performance liquid chromatography (HPLC)-ICP-MS detection. The CMCME-ICPMS system is applicable for the analysis of MeHg+ and Hg2+ with the ratio of lower than 5/1, with the limits of detection (LODs) of 2.6 (MeHg+) and 5.8 (Hg2+) ng L-1 and throughput of 8 h-1. Comparatively, the CMCMEHPLC-ICP-MS system is universal for Hg speciation in cells, providing LODs of 9.7 and 18.9 ng L-1 for MeHg+ and Hg2+ with a throughput of 10 h-1. Both systems exhibited good endurance to complex cell matrix and automated operation. The species analysis of Hg in cells incubated by Hg2+ or MeHg+ was achieved and the demethylation of MeHg+ in HepG2 cells was observed.