Micro-Column Separation/Pre-Concentration Combined with Fluorinating Electrothermal Vaporisation-Inductively Coupled Plasma-Mass Spectrometry for Determination of Trace Refractory Elements in Seawater, Soil and Sediment

A new, rapid and highly efficient method for the determination of trace amounts of refractory elements (titanium, zirconium, hafnium, vanadium, niobium, tantalum, molybdenum) using micro-column separation/pre-concentration combined with fluorinating electrothermal vaporisation-inductively coupled plasma-mass spectrometry (FETV-ICP-MS) has been developed. In this method, trace amounts of the analytes were selectively adsorbed by a conical micro-column packed with the solid phase extraction material N -benzoyl- N -phenylhydroxylamine loaded on microcrystalline naphthalene at desired pH values. Various factors influencing the separation/pre-concentration, such as pH, sample flow rate and sample volume were studied in detail, and the influences of the organic matrix and the pre-ashing temperature on the determined results were also investigated. Under optimal conditions, the detection limits for Ti, Zr, Hf, V, Nb, Ta and Mo were 0.016, 0.011, 0.010, 0.007, 0.005, 0.006 and 0.003 ng ml⁻¹, respectively, and the relative standard deviations ranged from 3.3% (Nb) to 9.6% (Hf) ( C = 0.20 ng ml⁻¹, n = 9). In order to validate the method, the proposed method was applied to the analysis of three certified reference materials (soils GBW07401 and GBW07425; sediment GBW07301a) and the results obtained were in good agreement with the reference values. The method was also successfully applied to the analysis of real seawater samples with satisfactory results.