Quantification of Gallium in Bauxites by Inductively Coupled Plasma-Atomic Emission Spectrometry-Comparison of Sample Pretreatment Methods between Alkali Fusion and Acid Dissolution

Two different sample pretreatment methods-NaOH alkali fusion method and HCl-HNO₃-HF-HClO₄ acid dissolution method were compared in order to quantify Ga in bauxite ore samples by inductively coupled plasma-atomic emission spectrometry (ICP-AES). The loaded reagents, chemical procedure, selection of analysis spectral lines and interferences are discussed in this paper. National Standard Reference bauxite ore samples with different Ga contents were analyzed by using both sample pretreatment methods. The analytical results indicate that the bauxite ore samples were incompletely dissolved by using HCl-HNO₃-HF-HClO₄ acids, which provided an incorrect result. Meanwhile, the pretreatment for bauxite ore samples with sodium hydroxide by alkali fusion provided higher accuracy and precision, giving a range of 2.51%-5.97% (RSD, n=11) and a detection limit for Ga of 0.15 μg/g with recoveries of the method ranging from 94.8% to 108.2%. The reliability of the alkali fusion method has been tested by quantification of Ga in National Standard Reference materials and the results were in agreement with the certified values. This method has advantages of rapid analysis, simple operation and more efficient measurement of Ga in bauxite ore samples.