Role of sample decomposition and preconcentration in elemental trace analysis

Abstract

-Progress in elemental trace analysis means that lower concentrations can be determined in a more reliable and efficient way. The demands posed to trace element analysis follow generally the tendency that lower and lower concentrations should be determined in matrices which become more and more complex. The most economical scientific strategy depends strongly on the element to be determined, on the kind of sample and especially, on the power of detection. Therefore, we must develop the strategy of determination in view of two widely differing thoughts: 1. It is necessary to apply direct instrumental methods for routine analysis in order to save time and man-power. This can be done only, if the required power of detection is asserted in view of a suff icient reliability of the results. 2. Multi-stage combined procedures have to be preferred in all cases, where direct instrumental methods still yield insufficient or incorrect results, in spite of the fact that they are usually more time and/or labour consuming.This paper intends to concentrate in particular on these procedures, in which decomposition and preconcentration methods have to precede the actual end-determination. The main goal is the minimization of systematic errors which become more crucial at the low concentrations involved. Especially those combined methods of a high degree of universality and reliability will be considered.Examples will be given for the determination of Hg, Se, Tl and B at ng/g and pg/g levels.

Analytical Chemistry of Element Determination (Non‐Nuclear and Nuclear)

“…Over the past two or three decades, the most commonly applied decomposition procedures for foods and related biological materials have been conventional wet ashing (digestion) and dry ashing, with increased current interest in microwaveassisted wet digestion and slurry preparation. Subsets of these and other techniques used for specific applications, of more limited applicability and used more sporadically include: no treatment or direct use of liquid Ihnat (2003); based on the classification scheme of Sansoni and Panday (1983) with additions from their text and other sources: (Bock 1979, Laporte et al 1975, Ihnat 2000b, Taylor et al 1997, Lamble and Hill 1998, de Bono and Velosa 1991Van Loon 1985, Williams 1978, Baruthio et al 1988, Smith and Arsenault 1996, Ure et al 1988, Gorsuch 1967, Koch and Koch-Dedic 1964, Joslyn 1970, Tölg 1983, Bendicho and de Loos-Vollebregt 1991, Hoenig 2001, Jacobs 1978, Carey and Caruso 1992, FAO 1980, Krause et al 1995, Gorsuch 1965, Langmyhr and Wibetoe 1985, Dunlop 1961, Gorsuch 1959, Gustin and Ogg 1965, Stoeppler 1997a, Totland et al 1992, Burguera and Burguera 1998a, Ure 1975, DeMenna 1994, Shamberger 1983, Watson 1994, Boyer and Horwitz 1986, Olson et al 1973, M...…”