High-yield sample introduction using nebulized film dielectric barrier discharge assisted chelate vapor generation for trace rare earth elements determination by inductively coupled plasma mass spectrometry

Abstract

A new sample introduction method of nebulized film dielectric barrier discharge (NFDBD) assisted chelate vapor generation coupled with inductively coupled plasma mass spectrometry (ICP-MS) for trace rare earth elements (REEs) determination in environmental water was developed in this work. Using 2,2,6,6-tetramethyl-3,5-heptanedione (DPM) as chelating reagent, the volatile and stable chelates of REE-DPM were effectively vaporized in NFDBD sampling system, leading to 8–9 folds enhancement of REEs sensitivity compared with solution nebulization sampling system, with the sample introduction efficiencies between 51.9% and 66.0%. The enhancement mechanism and the experimental parameters for REEs determination including the DPM concentration, the carrier solution concentration, the input discharge voltage and the argon flow rate were evaluated in detail. The interferences from sample matrix at 10 mg L−1 level and the degradation product of DPM at 0.5 mmol L−1 were also found negligible for trace REEs determination in NFDBD sampling system. Under optimized conditions, the relative standard deviations for 15 REEs were between 0.3% and 2.5% at the concentration of 0.5 μg L−1 and the detection limits for 15 REEs were between 0.0009 and 0.11 ng L−1, which were 1–2 orders of magnitude lower than other sampling systems such as solution nebulization, membrane desolvation, ultrasonic nebulization and electrothermal vaporization and 2–4 folds lower than NFDBD vapor generation system without chelate. This proposed method not only can be used for trace REEs determination directly in freshwater samples, but also is promising for seawater determination without column separation.