Number: 2007-041-1-500
Title: Mechanistic Aspects of Chemical Vapor Generation of volatile
hydrides for trace element determination
Task Group
Chairman: Alessandro D'Ulivo
Members: Jiri Dedina, Ralph Sturgeon, Qiuquan Wang, Bernhard
Welz, and Zoltan Mester
Objective:
Clarification of controversial aspects related to formation of trace
element hydrides/volatile metals species using aqueous phase reaction
by borane complexes as derivatization reagents.
Description:
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.
Progress:
Last Update: 2 January 2008
<project announcement published
in Chem. Int. 30(3) 2008>