Determination of rare earth elements in single mineral grains by laser ablation microprobe–inductively coupled plasma mass spectrometry—preliminary study

Abstract

The application of a laser ablation microprobe with high spatial resolution coupled with an inductively coupled plasma mass spectrometer to determine rare earth elements (REE) in single mineral grains is described. The REE were determined down to sub-ppm concentrations using a 40 µm diameter ablation crater; quantification at the 100 ppm level using a 4 µm diameter crater was demonstrated. A dual gas flow sample introduction system was used to permit calibration of the ICP mass spectrometer with aqueous standards. Repeatability of the order of ± 10% relative was achieved with the use of an internal standard when ablating a grain of clinopyroxene. Laser ablation craters with diameters of less than 5 µm were used to probe REE distributions within a grain of monazite. Comparison with data obtained by electron probe microanalysis (EPMA) showed that the detection limits using high resolution laser ablation ICP-MS were superior to those of EPMA for this application.