A quantification strategy in laser ablation ICP-MS based on the transported aerosol particle volume determined by optical particle size measurement

Abstract

The quantification strategy presented in this study is based on simultaneous measurements of laser ablation ICP-MS signal intensities and aerosol particle size distributions. Together with the bulk density of the sample ablated, this allows assessment of the relative mass of the particles introduced into the ICP-MS. This mass was reduced by the particles larger than the ionisation size limit of the ICP and was used to correct for variations in sample ablation and aerosol transport, allowing non matrix-matched calibration without using an internal standard element. A constant fraction of the aerosol (∼1%) was separated and diluted by a bucket wheel aerosol diluter and particle size distributions were measured by light scattering measurements in the diluted aerosol using an optical particle counter (OPC). The main part of the aerosol (∼99%) was used for ICP-MS measurements. Results using NIST SRM 610 as external standard show deviations of less than 10% compared with internal standardisation for various sample matrices such as NIST SRM 612/14 glasses, basaltic glass (BCR-2G) and fluorite. However, expanding the quantification approach to metals and non-metals for sample and standard is not advisable due to variations in the size classification of the aerosol particles between metals and non-metals.