Biosilica layer-by-layer modified with polyamines and carboxyarsenazo for REE preconcentration prior to ICP-MS determination in lignites and volcanic fumarole sediment

Biosilica-based adsorbents prepared from rice husk, sequentially modified with polymeric polyamines and carboxyarsenazo were proposed for the preconcentration of 13 lanthanides, La, Sc, and Y. It is shown that the proposed adsorbent quantitatively extracted rare earth elements (REEs) from solutions with pH 3.5-6.5. Carrying out adsorption at pH 3.5-4.5 allows the quantitative separation of rare earth elements from accompanying ions of non-ferrous, alkaline and alkaline-earth metals. A procedure for solid-phase extraction followed by mass spectrometric determination (SPE-ICP-MS) of REEs has been developed, which includes passing of 100 mL of the analyzed solution (pH 4) through a column with the adsorbent at a flow rate of 1 mL min(-1), elution of REEs with 5 mL 1 M HNO3(a preconcentration factor of 20) and subsequent determination of elements in the eluate by inductively coupled plasma mass spectrometry (ICP-MS). The accuracy of the results was confirmed by the recovery test of spiked samples and by analysis of a Certified Reference Material. The limit of detection was 0.04-10.9 ng L-1. The procedure was used for determination of REEs in lignites from Krasnoyarsk Krai (Russia) and fumarole sediment from Kudryavy volcano of the Greater Kuril Chain (Sakhalin Oblast, Russia).