Spatially-resolved analysis of solids by laser ablation-inductively coupled plasma-mass spectrometry: trace elemental quantification without matrix-matched solid standards

A two-point calibration method for laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) is assessed. Desolvated particles from a Teflon microconcentric nebulizer and particles ablated from a localized position on a solid sample are mixed and introduced simultaneously into an ICP magnetic sector mass spectrometer. Analyte signals from the solution are compared with those from the ablated solid for calibration. Matrix-matched or pelletized solid standards and prior knowledge of sample composition are not required for calibration. The transport of sample particulates from the ablation cell is measured online with a piezoelectric microbalance to provide signal normalization. The relative accuracy of the quantitative analysis of NIST SRM 612 glass and NIST SRM 1264a steel is 3% to 12%, respectively, except for the elements Pb and Bi in steel. These two elements are distributed heterogeneously and are probably subject to fractionation. The use of helium instead of argon as transport gas reduced fractionation but did not eliminate it. The analyte concentrations were approximately 15-51 ppm in NIST SRM 612 glass and 9-2500 ppm in NIST SRM 1264a steel.