Enhanced Photochemical Vapor Generation for the Determination of Bismuth by Inductively Coupled Plasma Mass Spectrometry

Abstract

An enhanced photochemical vapor generation (PVG) sample introduction procedure is developed for the determination of trace Bi with inductively coupled plasma mass spectrometry (ICP MS) by the addition of iron. Gas chromatography mass spectrometry (GC-MS) reveals that (CH₃)₃Bi is the major component of the volatile Bi species formed in the presence of 20% (v/v) acetic acid, 5% (v/v) formic acid, and 60 μg mL^-1 Fe³⁺ under UV irradiation. The addition of Fe³⁺ not only largely increases the PVG efficiency of Bi³⁺ but also accelerates the reaction kinetics of photochemical reduction of Bi³⁺. The analytical sensitivity was enhanced 30-fold using PVG for sample introduction compared to that for direct solution nebulization detection by ICP MS detection. Furthermore, the proposed method shows much better tolerance of interference from Cu²⁺ and Ni²⁺ than that from conventional hydride generation (HG). Under the optimized conditions, a detection limit of 0.3 ng L^-1 was obtained for Bi by ICP MS determination. The relative standard deviation (RSD) was 2.5% for seven replicate measurements of 0.5 ng mL^-1 Bi³⁺ standard solution. The proposed method has been successfully applied for the determination of Bi in environmental samples, including water samples, and certified reference material of soil (GSS-1) and sediments (GSD-5a and GSD-10) with satisfying results.