S. Akman et G. Doner, INTERFERENCE MECHANISMS OF SODIUM-CHLORIDE ON ZINC AND COBALT IN GRAPHITE-FURNACE ATOMIC-ABSORPTION SPECTROMETRY USING A DUAL CAVITY PLATFORM, Spectrochimica acta, Part B: Atomic spectroscopy, 49(7), 1994, pp. 665-675
The interferences of sodium chloride with the determination of a volat
ile (zinc) and a low volatility (cobalt) element by graphite furnace a
tomic absorption spectrometry (GFAAS) were examined. For various masse
s of the sodium chloride, the effects of pretreatment temperature and
time, and heating rate on the atomization of the analyte were investig
ated using a specially designed dual cavity platform, which in princip
le allows the analyte and the interferent to vaporize from the separat
e cavities so that gas and condensed phase interferences can be distin
guished to some extent. In addition, background and atomic absorption
signals obtained in the pretreatment step provided very important info
rmation to clarify the interference mechanisms. In the presence of sod
ium chloride, formation of a highly volatile zinc chloride contributes
mainly to the losses of zinc, especially during high pretreatment tem
peratures. The losses of zinc and cobalt can partly be attributed to t
he occlusion of the analytes in microcrystals of the interferent and s
ome of these are thrown from the furnace without decomposing early in
the atomization step or during the pretreatment step. In addition, exp
ulsion of both analytes together with the violently expanding matrix g
ases seems to be a likely interference mechanism as well.