3D Printed All-in-One Sample Introduction System for ICP-MS: Integrating Chip-Based Array Monolithic Microextraction, Microvalve Control, and Microflow Nebulizer

Three-dimensional printing (3DP) technology was applied to fabricate an all-in-one sample introduction system for inductively coupled plasma mass spectrometry (ICP-MS) analysis of ultratrace rare-earth elements (REEs) in cells. The developed 3DP all-in-one sample introduction system comprised a microfluidic chip integrating cell lysis and monolithic microextraction array, a microvalve control unit, and a microflow total consumption high-efficiency nebulizer (MTHEN). It made full use of the advantages of 3DP in preparing user-customized three-dimensional structures. On the one hand, an integrated chip consisting of a three-dimensional mixing zone and array monolithic columns with a skeleton structure of UiO-66 was printed directly, which are beneficial for mixing the cells with lysis buffer and extraction of target elements from the cell lysate, respectively, as well as improving the mass transfer. On the other hand, the 3DP-MTHEN with a customized interface was directly connected to an ICP torch, providing a high sample transport efficiency (81.1%) under a low flow rate of 6 μL min^-1. The sensitivity of ICP-MS by using a 3DP-MTHEN for representative elements was 4.7-6.0 times higher than that obtained by using a commercial microflow Burgener SC175 nebulizer (detection limits of 0.7-13.3 vs 0.7-52.6 ng L^-1). Besides, the 3DP-MTHEN exhibited a lower cost ($13 vs 1550). The proposed system has been applied to the determination of ultratrace REEs in MCF-7 cells. It exhibited simple operation, low cell consumption (500 cells), good precision (2.2-11.9%), low detection limit (1.3-8.6 ng L^-1), and quantitative recovery (71.9%-119%). It merits application potential for ultratrace elemental analysis in samples with very limited volume, especially cells.