Dual mass spectrometers with plasma-based ion sources for multiplex imaging of elements and biomolecules†

Abstract

Simultaneous imaging analysis of both elements and biomolecules was conducted by the split-flow laser ablation technique using two mass spectrometers equipped with different plasma-based ion sources. The laser-induced sample particles were split into two streams, and introduced into inductively coupled plasma mass spectrometry (ICP-MS) for detection of elements through hard ionisation, and dielectric barrier discharge ionization mass spectrometry (DBDI-MS) for detection of biomolecules through soft ionisation. Selenomethionine was used to optimise the heater current for DBDI-MS and to demonstrate the system's capability for simultaneous detection. The analytical capability of the present technique was demonstrated on mouse brain tissue sections, where elemental maps of Mg, P, Fe, Cu, Zn, and Mo were generated alongside molecular images of lipids and metabolites such as cholesterol, ceramide, sulfatides, and adenine. The imaging results highlighted distinct spatial distributions of elements and biomolecules, correlating them with physiological and structural regions of the brain.