Determination of Trace Se and Te in Geological Samples by Photochemical Vapour Generation Combined with Inductively Coupled Plasma-Mass Spectrometry

Abstract

An analytical method to accurately determine trace levels of Se and Te is essential to meet the growing importance of these elements to Earth science research. Herein, an in-house assembled photochemical vapour generation (PVG) unit, instead of normal sample nebulisation, with inductively coupled plasma-mass spectrometry (ICP-MS), was developed for the detection of Se and Te in geological samples. The major parameters that might potentially influence the PVG efficiencies of Se(IV) and Te(IV) were investigated. The unit could fully generate volatile species under 30 s of ultraviolet irradiation in the presence of 15% v/v formic acid, 15% v/v acetic acid and 50 mg l^-1 of Co²⁺. Under optimised conditions, the limit of detections (LODs, 3s, n = 11) of the proposed method were 0.5 ng l^-1 for Se and 0.6 ng l^-1 for Te. The RSDs of Se and Te were 2.0% and 2.3% (1 μg l^-1, n = 7), respectively. Interference experiments showed that Fe, Ti, V and Cu have certain negative effects, so the standard addition method was used for real sample analysis. Measurement results for eleven CRMs, including soils (GSS-4, GSS-7), sediments (GSD-9, GSD-10) and rocks (GSR-1, GSR-2, GSR-3, GSR-5, AGV-2, GSP-2 and W-2a), were consistent with literature values, and showed better precision, indicating the feasibility of the proposed method for determination of trace Se and Te in geological samples.