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Pure Appl. Chem., 2011, Vol. 83, No. 6, pp. 1283-1340

Published online 2011-03-16

Mechanisms of chemical generation of volatile hydrides for trace element determination (IUPAC Technical Report)

Alessandro D’Ulivo1*, Jiří Dědina2, Zoltan Mester3, Ralph E. Sturgeon3, Qiuquan Wang4 and Bernhard Welz5

1 National Research Council of Italy (C.N.R.), Institute of Chemistry of Organometallic Compounds, C.N.R., Via G. Moruzzi, 1 56124 Pisa, Italy
2 Institute of Analytical Chemistry of the ASCR, v.v.i., Veveří 97, 602 00 Brno, Czech Republic
3 Institute for National Measurement Standards, N.R.C. Canada, 1200 Montreal Road, Ottawa, ON K1A 0R6, Canada
4 College of Chemistry and Chemical Engineering, Xiamen University, Key Laboratory of Analytical Sciences, Xiamen 361005, China
5 Department of Chemistry, Universidade Federal de Santa Catarina, Florianòpolis-SC 88040-900, Brazil

Abstract: Aqueous-phase chemical generation of volatile hydrides (CHG) by derivatization with borane complexes is one of the most powerful and widely employed methods for determination and speciation analysis of trace and ultratrace elements (viz. Ge, Sn, Pb, As, Sb, Bi, Se, Te, Hg, Cd, and, more recently, several transition and noble metals) when coupled with atomic and mass spectrometric detection techniques. Analytical CHG is still dominated by erroneous concepts, which have been disseminated and consolidated within the analytical scientific community over the course of many years. The overall approach to CHG has thus remained completely empirical, which hinders possibilities for further development. This report is focused on the rationalization and clarification of fundamental aspects related to CHG: (i) mechanism of hydrolysis of borane complexes; (ii) mechanism of hydrogen transfer from the borane complex to the analytical substrate; (iii) mechanisms through which the different chemical reaction conditions control the CHG process; and (iv) mechanism of action of chemical additives and foreign species. Enhanced comprehension of these different mechanisms and their mutual influence can be achieved in light of the present state of knowledge. This provides the tools to explain the reactivity of a CHG system and contributes to the clarification of several controversial aspects and the elimination of erroneous concepts in CHG.