Thiol-Functionalized Magnetic Biochar as an Efficient Sorbent for Magnetic Dispersive Micro-SPE Coupled with ICP-MS Determination of Pb(II), Cd(II), and Hg(II) in Environmental Waters

Abstract

A thiol-functionalized magnetic biochar (MB-SH) was synthesized and utilized as an efficient sorbent for magnetic dispersive micro-solid-phase extraction (MD-µSPE) coupled with inductively coupled plasma mass spectrometry (ICP-MS) for the simultaneous determination of trace Pb(II), Cd(II), and Hg(II) in environmental water samples. The MB-SH material was created by functionalizing magnetic biochar with thiol groups, resulting in high-density chelating sites for heavy metal ions. The optimized MD-µSPE process allowed for quick preconcentration of target analytes in 3-5 minutes, with preconcentration factors ranging from 100 to 250. Under ideal circumstances (pH 5.5, 20 mg sorbent, 250 mL sample volume, 2 mL eluent), the method obtained limits of detection at the ng/L level (0.5-1.2 ng/L), exceptional recoveries of 90-102%, and relative standard deviations of <5%. The approach was successfully used on both natural and industrial water samples, displaying good accuracy when compared to certified reference material (SRM 1643e). The MB-SH sorbent demonstrated good reusability for at least five cycles with low performance loss, providing a green, cost-effective, and sustainable alternative to trace heavy metal monitoring in aquatic environments.