A magnesium hydroxide preconcentration/matrix reduction method for the analysis of rare earth elements in water samples using laser ablation inductively coupled plasma mass spectrometry

This paper describes a simple method for simultaneous preconcentration and matrix reduction during the analysis of rare earth elements (REEs) in water samples through laser ablation inductively coupled plasma mass spectrometry (LA–ICP–MS). From a systematic investigation of the co-precipitation of REEs using magnesium hydroxide, we optimized the effects of several parameters – the pH, the amount of magnesium, the shaking time, the efficiency of Ba removal, and the sample matrix – to ensure quantitative recoveries. We employed repetitive laser ablation to remove the dried-droplet samples from the filter medium and introduce them into the ICP–MS system for determinations of REEs. The enrichment factors ranged from 8 to 88. The detection limit, at an enrichment factor of 32, ranged from 0.03 to 0.20 pg mL−1. The relative standard deviations for the determination of REEs at a concentration of 1 ng mL−1 when processing 40 mL sample solution were 2.0–4.8%. We applied this method to the satisfactory determination of REEs in lake water and synthetic seawater samples.