Current advances of chemical vapor generation in non-tetrahydroborate media for analytical atomic spectrometry

The utilization of chemical vapor generation (CVG) as a sample introduction method for analytical atomic spectrometry has been an important subject of numerous studies for more than 50 years. The sustained interest in CVG is driven by not only the intrinsic advantages of this technique, but also the quest for even better detection power based on higher vapor generation efficiency and stronger anti-interference capability, as well as an expansion of the scope of CVG to encompass more detectable analytes. Historically, reduction by tetrahydroborates (THBs) appears to be the most successful for especially hydride-forming elements, whereas interferences from transition metals, the in-depth characterization of the volatile species as well as practical applications can remain a hard nut to crack. For the past decade, several new types of CVG outperforming conventional hydride generation have been explored, which considerably promote the development of this technique in atomic spectrometric and non-atomic spectrometric areas. The objective of the present review is, on one hand, to assimilate the recent advances of CVG in non-THB media, with special attention paid to photochemical vapor generation and plasma-induced vapor generation; on the other hand, since a deep understanding in the mechanism of these CVGs is of utmost importance and broad interest to a sizable research community, with examples drawn from literature and our own recent work, the interpretation of the intermediates and resultant volatile products are also highlighted, along with characterization tools that could be beneficial for this purpose. We finally provide some insights into the directions for future CVG research for analytical chemistry. • Current advances of chemical vapor generation except hydride generation is reviewed for analytical atomic spectrometry. • Special attention is paid to photochemical vapor generation and plasma-induced vapor generation. • Characterization and identification of the intermediates and resultant volatile products are highlighted for interpretation of the mechanisms. • Some insights into the developing directions for future CVG are provided for analytical chemistry.