Behaviour of selenium and tellurium in the presence of various modifiers in electrothermal atomic absorption spectrometry

Abstract

The behaviour of selenium and tellurium dissolved in nitric, hydrochloric or perchloric acid and in their mixtures was tested during the atomization process in a graphite tube with a platform. Palladium, magnesium nitrate and their mixture were used as the modi®ers. It was found that palladium is a good modi®er for selenium only in pure nitric or hydrochloric acid solutions. In perchloric acid and in all mixed media, selenium in the presence of palladium is lost almost completely during the evaporation and drying of the sample. Magnesium nitrate used as modi®er is superior to palladium since it thermally stabilizes selenium in all the media investigated up to 1200 ³C. A different situation was found for tellurium. Both modi®ers protect it in all solutions against losses during the ®rst stages of the atomization process; however, magnesium stabilizes it only to 800 ³C whereas palladium is effective up to 1200 ³C. If a mixture of both modi®ers is used in the determination of selenium and tellurium, then its activity is identical with the activity of the component of the mixture that is the more effective when the components are applied individually as modi®er. No effects suggesting a joint action of both components were found. The mechanism of activity of the modi®ers tested is discussed.

Use of solid-phase extraction to eliminate interferences in the determination of mercury by flow-injection CV AAS

“…A solution of 1,10-phenanthroline and thiosemicarbazide has been applied to suppress the effects of Cu, Pb, Ag, Au, Pt, Pd, and Se [9]. It was also found that the standard addition and successive dilution might be successfully used in the presence of Zn, Bi, Cd, and Pt [10]. Welz and SchubertJacobs [11] proposed the addition of Fe(III) in the presence of hydrochloric acid to eliminate the effects of copper, nickel, and silver.…”

“…Most pronounced are chemical interferences particularly those caused by elements that could simultaneously undergo reduction and form amalgams [9,10]. A solution of 1,10-phenanthroline and thiosemicarbazide has been applied to suppress the effects of Cu, Pb, Ag, Au, Pt, Pd, and Se [9].…”

Determination of mercury in estuarine sediments by flow injection-cold vapour atomic absorption spectrometry after microwave extraction

“…MADRID et al [13] found that Cd(II) and Pb(II) do not interfere, although Se(IV), Ni(II) and Cu(II) depressed significantly the analytical signal of Hg. PSZOINCKI et al [10] investigated several ions and detected negative influence of Cu(II), Ag(I), Se(IV), Au(III), Pd(II) and Te(IV) on the analytical signal of Hg, at low concentrations. They used successfully the successive dilution method to eliminate these interferent effects.…”

“…The CVAAS technique is based on the reduction of mercury compounds present in samples to free metal, followed by transformation of the metal into atomic vapour which is measured [10]. It seems, therefore, that this technique should be free from interferences.…”

“…It seems, therefore, that this technique should be free from interferences. The literature reports, however, that many elements as Ag, Au, Pt, Pd, Cu, Ni, Pb and Se significantly affect the mercury analytical signals [9][10][11][12][13].…”