Non-chromatographic Speciation Analysis of Tellurium by HG-ICP–MS/MS at Sub ng L^–1 Concentration in Natural Waters Using Ti^III as a Pre-Reducing Agent

Abstract

An automated and high-throughput (36 h–1) method for extremely sensitive determination of the two main tellurium species in the environment, namely, tellurite (TeIV) and tellurate (TeVI), was developed. Flow injection hydride generation was interfaced for the first time with inductively coupled plasma triple quadrupole mass spectrometry (ICP–MS/MS) detection to assure interference-free tellurium analysis. ICP–MS/MS conditions were studied in detail. Using a mixture of He + O2 gases in the reaction cell, the background signals significantly dropped and Xe isobaric interference was eliminated, allowing measurement with the most abundant Te isotopes, that is, 128Te and 130Te, and offering a huge increase in sensitivity. Volatile H2Te was selectively generated by a HCl/NaBH4 reaction from TeIV or from both TeIV and TeVI (TeIV+VI) after pre-reduction of TeVI by a TiCl3 solution. The optimum conditions for TiCl3 as a pre-reductant and the pre-reduction kinetics were also investigated. Different reduction rates were found depending on the sample stabilization media (HCl, HNO3, or EDTA). The same sensitivity was found for TeIV and TeVI, measured after pre-reduction, and no significant matrix effect was observed in both fresh and seawaters. Therefore, external calibration was used for quantification in real samples. Under optimal conditions, this method reached an unprecedented limit of detection of 0.07 ng L–1 for both TeIV and TeIV+VI and an intra-day repeatability of 5.2% at the 5 ng L–1 level. The methodology was successfully applied to the speciation analyses in commercially available certified reference materials of river water and seawater, and in bottled water and lake water samples.

Atomic spectrometry update – a review of advances in environmental analysis

“…The method was successfully validated against the NRCC CRMs SLRS-3 and 4 (river water). In the HG-ICP-MS determination of Te, elimination of 128 Xe and 130 Xe interferences on the most abundant isotopes 128 Te and 130 Te meant 79 that an LOD of 0.07 ng L −1 could be achieved, thereby making the determination of Te in lake, river, bottled and seawaters possible. Results for total Te in six CRMs agreed well with certificate values.…”

Atomic spectrometry update: review of advances in elemental speciation

“…Garcia-Figueroa et al explored the capabilities of ICP-MS/MS to reduce the influence of spectral interferences on the most natural abundant Te isotopes. 122 For this purpose, FI-HG was interfaced to ICP-MS/MS. Most of the paper is devoted to the optimisation of the experimental conditions affecting HG-ICP-MS/MS.…”