Selection of internal standards for analysis of silicate rocks and limestones by laser ablation inductively coupled plasma atomic emission spectrometry (LA-ICP-AES)

Included (Si, Ca) and added (Li, B) internal standards (IS) have been used comparatively in LA-ICP-AES of silicates and limestones to improve both precision and accuracy. A Q-switched Nd:YAG laser (355 nm, 10 Hz, 10 mJ per shot) has been applied for ablation. Samples have been prepared by fusion with Li₂B₄O₇ and measured using a Perkin-Elmer Optima 3000 ICP system. Both types of IS have given a relative standard deviation (RSD) less than 2–1%, which improved the repeatability by a factor of 2–10 and calibration graphs have been linear over the whole concentration range.