Optimization of mass-spectrometer acquisition parameters for trace element analysis by LA-ICP-MS using magnetic sector instrument Element2

Abstract

Acquisition parameters for trace element analysis of minerals with the magnetic sector mass-spectrometer Element2 using laser ablation are discussed in the article. The main criteria for the parameters to be considered are optimal signal quality that would result in lowest values for limit of detection (LOD). Also, mineral analysis duration was taken into account in this work. The relationship between sample time and the number of runs was studied in the determination of REE, Y, and Nb in olivine that has low concentrations of these elements. Sample time was investigated in the range of 5-40 ms. Increasing the sample time resulted in a lowering of the standard deviation of analysis results and the LOD, although number of runs was significantly decreased. Additionally, the best way to minimize time of the analysis while maintaining signal quality was to use highest values for sample per peak and lowest mass window. The optimized acquisition parameters were determined as 100 samples per peak, a mass window of 4%, and a sample time of 20 ms. The possibility to reduce laser ablation up to 10 s (4 calculation runs) without loss of results’ quality was demonstrated under the studied conditions. This reduction could be beneficial for the analysis of thin mineral grains. The parameters were applied to the trace element analysis of olivine Shc, which has a similar origin to new olivine reference material MongOLSh11-2. Grains of different tints of color ranging from practically colorless and light green to light yellow and yellow were analysed. Despite significant concentration differences between grains of various colors, normalized REE distribution patterns were similar across all analysed grains. Therefore, this sample could serve as a within-laboratory reference standard for routine trace element analysis of olivine using LA-ICP-MS. Furthermore, olivine San Carlos, a widely used standard to validate analytical data, was also analysed using the optimized parameters. The results obtained in this study are consistent with literature data and supplement it with Lu concentrations.