Determination of trace rare earth elements in environmental samples by low temperature electrothermal vaporization inductively coupled plasma mass spectrometry after synergistic extraction with dimethylheptyl methyl phosphate and 1-phenyl-3-methyl-4-benzoyl-pyrazalone-5.

Synergistic extraction of trace rare earth elements (REEs) from nitrate solutions using mixtures of dimethylheptyl methyl phosphate (P350) and 1-phenyl-3-methyl-4-benzoyl-pyrazalone-5 (PMBP) in hexamethylene has been investigated. The factors affecting the synergistic extraction of rare earth ions, such as pH, organic solvent and phase ratio of organic phase to aqueous phase were systematically studied. The synergistic enhancement factors of P350 and PMBP for REEs were calculated to be 4.3-5.8. After the synergistic extraction, the postextraction organic phase was directly introduced into the graphite furnace for electrothermal vaporization inductively coupled plasma mass spectrometry (ETV-ICP-MS) determination. It was found that PMBP along with P350 has an obvious chemical modification for REEs, and the limits of detection (LODs) for 15 REEs were in the range of 0.02-0.09 ng L(-1). The proposed method was found to be more suitable for the analysis of environmental samples with complex matrix.