DETERMINATION OF THE RARE-EARTH ELEMENTS IN AQUEOUS SAMPLES AT SUB-PPT LEVELS BY INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRY AND FLOW-INJECTION ICPMS

A method has been developed for the determination of the rare earth el ements (REE) at concentrations down to 0.1 ppt (0.5 pmol kg(-1)) in aq ueous samples using now injection coupled to-an inductively coupled pl asma mass spectrometer. The method presented here is an extension of a n existing technique to allow application to a wider range of ionic st rengths. The method is sufficiently rapid to enable samples to be proc essed through the purification stage in less than 90 min, More than 99 .5% of the Ba in the sample is removed during processing, ensuring tha t isobaric interference of BaO on the REE is < 2% of the REE signal, T he detection limits of the method described here show an improvement o f up to 30 times better than the original method. This improvement was achieved by using how injection techniques that allow the sample to b e concentrated in a smaller volume for analysis. The new technique has been successfully employed for the determination of REE in Icelandic hydrothermal fluids.