Analytical Sciences

The Interference Effect of a Mixture of Magnesium, Aluminium, Sulfate and Chloride on the Atomization and Vaporization of Manganese in Graphite Furnace Atomic Absorption Spectrometry

H. INCE and S. AKMAN

Istanbul Teknik Üniversitesi, Fen-Edebiyat Fakütesi, Kimya Bölümü, 80626 Maslak, Istanbul, Turkey

In this study, the interference effects of Al³⁺, Mg²⁺, Cl^- and SO₄^2- ions on the determination of manganese by graphite furnace atomic absorption spectrometry (GFAAS) were investigated. At first, the interferences caused by Al₂(SO₄)₃, AlCl₃, MgCl₂ and MgSO₄, which are the most possible major compounds for the combinations of the ions mixed, were individually considered. Then, the effects caused by mixtures containing various amounts of MgSO₄ and AlCl₃ were studied. If the pyrolysis temperature is below 800°C, AlCl₃ changes the vaporization mechanism of manganese. These interferences disappear at higher pyrolysis temperatures. At the same time, aluminum salts may cause the formation of refractory compounds between aluminum and manganese (like spinel MnAl₂O₄) that shift the absorption signals of manganese to higher temperatures. Magnesium sulfate, by itself, does not cause any depression of manganese signals. In fact, it acts as a modifier, preventing volatilization losses of manganese during the pyrolysis step. A conclusion was reached that detailed investigation of the interferences in a complex media is a very difficult experimental and theoretical task. To solve practical problems, one may better follow the general notions developed in GFAAS toward complex matrices.

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