Food for Thought: A Critical Overview of Current Practical and Conceptual Challenges in Trace Element Analysis in Natural Waters

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

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.

Less-studied TCE: are their environmental concentrations increasing due to their use in new technologies?

The possible environmental impact of the recent increase in use of a group of technology-critical elements (Nb, Ta, Ga, In, Ge and Te) is analysed by reviewing published concentration profiles in environmental archives (ice cores, ombrotrophic peat bogs, freshwater sediments and moss surveys) and evaluating temporal trends in surface waters. No increase has so far been recorded. The low potential direct emissions of these elements, resulting from their absolute low production levels, make it unlikely that the increasing use of these elements in modern technology has any noticeable effect on their environmental concentrations on a global scale. This holds particularly true for those of these elements that are probably emitted in relatively high amounts from other human activities (i.e., coal combustion and non-ferrous smelting), such as In, the most studied element of the group.