Flow injection of slurries of a lithium borate fusion disc for multi-elemental analysis by mixed-gas inductively coupled plasma mass spectrometry

Abstract

A method was devised for the direct analysis of slurries of a lithium borate fused disc of SY-4 (Diorite Gneiss) by ICPMS with a mixed-gas plasma and flow injection for the introduction of slurries into the ICP. Various surfactants and concentrations were tested to homogenously suspend the ground particulate in solution. A 4% (m/m) solution of Triton X-100 in 2% v/v HNO₃ was found to produce highly reproducible injection peaks. In an attempt to matrix match the calibration solutions, solid flux powder as well as standard solution Li were added to the calibration solutions. However, both additions failed to adequately correct for the observed effects with/without the use of an internal standard, suggesting a sample introduction problem. To test this, the sample uptake rate was halved, and slurry dilution was increased from 3.2% (m/v) to 0.8% and 0.4% (m/v). With the 0.8% (m/v) suspension, the majority of concentrations (for 11 out of 16 elements) measured by external calibration agreed with the certified values at the 95% confidence level when an ⁷⁶Ar₂⁺ dimer was used as an internal standard.