A Method for Determination of Transport Efficiency in Laser Ablation Inductively Coupled Plasma Mass Spectrometry for Tissue Analysis

Abstract

Recent studies have demonstrated the applicability of the “single particle” mode in laser ablation–inductively coupled plasma–mass spectrometry to map and size particles simultaneously. The transport efficiency (TE) is an important parameter in this configuration and affects the detection of individual nanoparticles, reliability of nanoparticle characterization, and related applications. This study introduces a novel method for the precise determination of TE, based on counting upconversion nanoparticles from gels characterized by fluorescent microscopy. The method was found to be most suitable for the 2940-nm laser ablation system, achieving virtually quantitative nanoparticle desorption, with TE primarily governed by ablation cell design and aerosol transport efficiency. With the 213-nm laser, attention had to be paid to incomplete desorption and possible nanoparticle redeposition at low laser fluences to avoid variability in TE measurements. Finally, use of the 193-nm laser-induced nanoparticle disintegration, resulting in elevated baseline noise and lower sensitivity, which prevented the use of this approach for the determination of TE. This study highlights the versatility of the proposed method, while also identifying its limitations, in terms of wavelength and fluence.