Methods for Improving the Sensitivity in Atom Trapping Flame Atomic Absorption Spectrometry: Analytical Scheme for the Direct Determination of Trace Elements in Beer

Abstract

A method is described for the atomic absorption (AA) determination of Ag, Cd, Cu, Fe, In, Mn, Pb, Tl and Zn in beer using an ‘integrated atom trap’ system mounted on a standard AA air–acetylene flame burner. A new design of atom trapping technique that would exceed the operational capabilities of existing arrangements (a water-cooled single or dual silica tube or a double-slotted quartz tube) and permit construction of an ‘integrated trap’ was investigated. A significant improvement in detection limit was achieved compared with that obtained using either of the above atom trapping techniques separately. Rapid, accurate analyses can be achieved using continuous aspiration. The concentration detection limits were 3.0, 5.0, 1.2, 4.0 and 0.1 ng ml–1 for Cu, Fe, Mn, Pb and Zn, respectively, using a 2 min in situ preconcentration time. The relative standard deviations are of the order of 3.0–6.0% for this technique. Basic analytical performance characteristics are also given for Ag, Cd, In and Tl using various designs of atom trap. The designs studied include both slotted tube and single silica tube water-cooled atom traps.