Chip-based array magnetic solid phase microextraction on-line coupled with inductively coupled plasma mass spectrometry for the determination of trace heavy metals in cells

Determination of trace elements in cells is critical to metallomics research and still faces tremendous difficulties even with the help of highly sensitive inductively coupled plasma mass spectrometry (ICP-MS). Microfluidic chips offer a functional tool-set for cell analysis with features of miniaturization, integration and automation. In this work, we proposed a chip-based array magnetic solid phase microextraction (MSPME) system and on-line combined it with ICP-MS via microflow concentric nebulization for the determination of trace Cu, Zn, Cd, Hg, Pb and Bi in cells. Under the optimized conditions, the limits of detection of the developed on-line chip-based array MSPME-ICP-MS system are 49, 43, 4.2, 6.1, 13 and 18 ng L-1 for Cu, Zn, Cd, Hg, Pb and Bi, respectively. The proposed method was applied to the analysis of target heavy metals in three kinds of cells (HepG2, Jurkat T and MCF7), and the recoveries for the spiked samples were in the range of 83.8%-117%. The extractable species of the target metals in cells were also studied and the results demonstrated a high selectivity of the developed methods towards free metal ions and/or their small molecular species.