PALLADIUM AND MAGNESIUM-NITRATE AS MODIFIERS FOR THE DETERMINATION OFLEAD BY GRAPHITE-FURNACE ATOMIC-ABSORPTION SPECTROMETRY

It was found that palladium used as modifier for the determination of lead extends the range of the acceptable pyrolysis temperatures up to 1100-degrees-C. It eliminates at these temperatures the losses of lead due to evaporation in the form of chloride, intermetallic compounds w ith sodium or as elemental lead. It plays also an important role durin g the atomization phase by separation the atomization of lead from the atomization of more volatile components of the sample. Palladium in a ny form, however, is not able to eliminate the interference effect of chlorides, which decompose at the temperatures below 400-degrees-C and , under sonic conditions, it can become itself a strong interferent of similar type. The interference of easily decomposing chlorides may be eliminated only either by a strong acidification of the sample with n itric acid or by addition of an excess of magnesium nitrate or sodium nitrate.