Investigation and elimination of sodium nitrate—borate interference of manganese in electrothermal atomic absorption spectrometry

Abstract

Elimination of sodium nitrate–borate matrix interference on Mn and the effect of chemical modifiers in electrothermal atomic absorption spectrometry were investigated. Sodium nitrate–borate matrix (0.45 mol l^–1 NaNO₃–0.05 mol l^–1 H₃BO₃) decreased the integrated absorbance signal for Mn to 80% compared with the signal obtained from a matrix-free solution. The compounds Mg(NO₃)₂, Ni(NO₃)₂ and Pd(NO₃)₂ were examined as modifiers to improve the Mn signal in sodium nitrate–borate solution. The Ni(NO₃)₂ modifier gave a larger integrated absorbance signal for Mn than a matrix-free solution and the smallest background signal of the modifiers examined. This technique was applied to the determination of Mn in geological rock reference samples (feldspar JF-1 and granitic rock JG-2 from the Geological Survey of Japan). The analytical results agreed with the reference values and the relative standard deviations at the µg g^–1 level were within 2%(n= 5).