On-line method for inductively coupled plasma mass spectrometric determination of rare earth elements in highly saline brines

A rapid and reliable on-line preconcentration method for the determination of REE in sea-water and highly saline brines by ICP-MS was developed. The method is based on REE separation from the saline water by adsorption on a micro-column of silica-immobilized 8-hydroxyquinoline. After adsorption on the micro-column at pH 9, the REE are eluted with a small volume of mixed acids and introduced into the ICP-MS instrument. The system operates at low pressure. Total time of preconcentration and analysis is less than 10 min. Detection limits in highly saline waters range from 0.06 ng l(-1) for Tb and Ho to 0.6 ng l(-1) for Ce and Nd. Since there is no REE sea-water reference, the analytical results obtained by this method were compared with those quoted in the literature.