Indirect determination of tungstate in rat tissues by atomic absorption spectrometry

Abstract

An indirect method is described for the determination of tungsten as tungstate in tissue samples by atomic absorption spectrometry (AAS). Tungstate forms a stable ion-association complex [Fe(dipy)₃]²⁺WO^2–₄(dipy = 2,2′-dipyridyl) in acidic solution, which can be extracted into chloroform with an efficiency of higher than 98%. The extract can be analysed for iron (and hence indirectly for WO^2–₄) by flame AAS after stripping back into 60% perchloric acid. The calibration graph is linear up to 19 p.p.m. of WO^2–₄ and the limit of detection is 0.17 p.p.m. Many foreign ions do not interfere and the method has been applied successfully to the determination of tungstate in rattus norvegicus tissue samples.