IUPAC

Clarification of controversial aspects related to formation of trace element hydrides/volatile metals species using aqueous phase reaction by borane complexes as derivatization reagents.

Aqueous phase chemical vapor generation (CVG) by borane complex derivatization is one of the most powerful and worldwide employed method for determination and speciation of trace and ultratrace elements Ge, Sn, Pb, As, Sb, Bi, Se, Te, Hg, Cd and, more recently also several transition and noble metal, coupled with atomic spectrometric techniques.

Thousands of research papers and many regulated analytical methods are based on CVG. However, since its first application, more than 35 years ago, the application and validation of CVG to many different analytical targets has been the prevailing aspect, while only limited efforts has been dedicated to clarification of mechanistic aspects. Analytical CVG it is still dominated by erroneous concepts (as for example the nascent hydrogen theory) which has been disseminated and consolidated in the analytical scientific community in the course of many years. As a consequence, the approach to CVG remains quite empirical, which hinders the possibility of further development. A rationalization of the field, based on more rigorous scientific approach appears to be necessary, and it could be also an impulse for further development in CVG.

In the last decade significant efforts have been dedicated to experiments and literature survey devoted to clarification of the mechanism of hydrolysis of tetrahydroborate(III) and other borane complexes, the mechanism of generation of volatile hydrides (AsH₃, Me₂AsH, MeAsH₂, SbH₃, BiH₃, GeH₄ and SnH₄) and unknown or not yet identified volatile species of transition and noble metals. The collected evidences give a solid base for the rationalization of the mechanism involved in CVG techniques.