Abstract

CACERES CHOQUE, Luis Fernando. ANÁLISIS DE AGUAS, UNA APROXIMACIÓN QUÍMICO ESTADÍSTICA EN ENSAYOS DE INTERCOMPARACIÓN. Rev. Bol. Quim [online]. 2005, vol.22, n.1, pp.55-63. ISSN 0250-5460.

Taken as a base study, the statistical results of a comparative exercise, offers the possibility for a discussion, from a chemical and analytical point of view, of water analysis in order to explain the generated results in laboratories of the Andean Region. Atomic absorption spectroscopy is a usual technique in our laboratories which afford results in the following order : C.E. > Zn > Cu > Ni > Pb > Cd> Cr > As. The most important parameter regarding expectable results is C.E. The one representing a considerable number of problems is Chromium. Cadmium as well, is difficult to determine, according to data afforded by 45.5 % of the laboratories generating unexpected results. Regular results are often obtained out of Zn, which is ordinarily satisfactorily determined in 86% of laboratories. One interesting aspect to evaluate is the application of a previous treatment of samples as for instance acidic digestion. Such treatment effects different results when analyzing Cd, Cu, Cr, Ni and Zn. Arsenic and lead after the treatment do not manifest important changes. However, atomic absorption applied to arsenic via hydride generation techniques supposes a reduction (pre-treatment) before its determination. The surveyed laboratories show a high competence when determining C.E., Zn, Cu and Ni, on the other hand, Pb, Cd, Cr and As, are hardly ever precisely reported.

Keywords : análisis de aguas; inter-comparación; elementos traza.