Simultaneous Determination of Minor Tungsten, Tin and Molybdenum in Geological Samples by Inductively Coupled Plasma- Atomic Emission Spectrometry

A method for the simultaneous determination of tungsten, tin and molybdenum in geological samples by inductively coupled plasma-atomic emission spectrometry (ICP-AES) have been developed. In order to eliminate the matrix interference from coexist elements on the determination, the sample preparation method was studied. Samples were digested by HF at low temperature to remove silicon as volatile SiF₄ and the residues were decomposed by alkali fusion with Na₂O₂ followed by extraction with hot water and acidification with diluted HCl. W, Sn and Mo in the sample solution were then determined by ICP-AES. The linear ranges of the calibration curves for each element are 0~30 mg/L for W, 0~40.0 mg/L for Sn and 0~40.0 mg/L for Mo. The precision (RSD, n=12) of the method are <10.80%, <6.67% and <8.33% for W, Sn and Mo, respectively. The method has been applied to the determination of tungsten, tin and molybdenum in National Standard Reference materials and the results are in agreement with the certificated values.