Characterisation of matrix-based polyatomic interference formation in laser ablation-inductively coupled plasma-mass spectrometry using dried micro-droplet ablation and its relevance for bioimaging

Abstract

Dried micro-droplets were used to characterise the formation of polyatomic interferences in a commercial laser ablation-inductively coupled plasma-mass spectrometer (LA-ICP-MS). Droplets containing 4 ng each of Al, As, Ca, Cd, Co, Cu, Fe, Mg, Mn, P, Se and Zn in the presence of potentially interfering isotopes were deposited on silicate microscope slides. Comparisons of the total signal recorded for each dried droplet showed no detectable influence of polyatomic matrix-based interferences. Visualisation of acquired signal was achieved by the generation of two-dimensional maps. The natural abundance pattern of elements with two measurable isotopes was confirmed for each droplet. The lack of interferences was due to the absence of major gas molecules (e.g. N₂, O₂, CO₂) from the laser cell and minimal total matrix load on the plasma when compared to standard solution nebulisation (approx. ng s⁻¹versus 10–20 μL s⁻¹) ICP-MS conditions.