A rapid and accurate method for the determination of Zr in geological materials is presented. The interference of F
- was reduced by masking with Al
+, and Fe
3+ was reduced to Fe
2+ with hydrazinium dichloride. A sample (0.2 g) was decomposed with a mixture of HNO
3, HClO
4 and HF, and the solution was evaporated to dryness. Then the dried sample was fused with a mixture of 2 g Na
2CO
3 and 0.3 g H
3BO
3, and the melt was dissolved in 17 ml of HCl (1 + 1), and it was diluted to 50 ml with water. Fifteen ml portion of the sample solution was transferred to a 50 ml volumetric flask. To it, 8 ml of Al chloride solution (Al
3+ 25 mg/ml) and 5 ml of hydrazinium dichloride solution (15 w/v%) was added. The solution was heated in boiling water for 15 min. After cooling, 5 ml of Xylenol Orange solution (0.1 w/v%) was added and diluted up to the mark with water. Absorbance was measured at 535 nm. Ten samples could be analyzed in 5 h. This method was satisfactorily applied to a variety of geological reference materials.
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