Abstract

A new approach to matrix modification, in which polyhydroxy compounds (polyols) were used as complexing agents, has been evaluated for the determination of trace elements (B, As, Se, Sb, Cr and Mo) by electrothermal vaporization inductively coupled plasma mass spectrometry (ETV-ICP-MS). The effects of eight kinds of polyhydroxy compounds on the sensitivity enhancement of elements were studied. From the results, the addition of mannitol and sorbitol has the best effect for sensitivity enhancement of the tested elements (B, As, Se and Sb) by a factor of 2.5–84 compared to results without modifiers by electrothermal vaporization ICP-MS. The sensitivity enhancement is attributed to the fact that various polyhydroxy compounds form volatile complexes with the elements and assist in transporting them from the ETV system to the ICP-MS instrument. The instrumental parameters for ETV-ICP-MS, such as gas flow rate, ashing temperature and vaporization temperature, were studied and optimized. With the established method, the limits of detection for the elements of interest in the presence of mannitol and sorbitol were about 1–100 pg mL⁻¹, which is about 1–2 orders lower than levels achieved in the absence of them. The interferences from Ca, Mg, Na and K, which exist abundantly in natural water samples, on the analytical performance of the analytes were examined. From the results, the coexisting elements markedly changed the volatility of the analyte–polyol complexes, which resulted in a decrease in the detection sensitivity of the analytes. The established matrix modification system was applied to the determination of elements (As, B, Se and Sb) in various water samples. The feasibility of the proposed method was tested by using NIST SRM 1643 C Water samples.