摘要：Nitrate ion quantitatively interferes in the complexation of rhenium and dimethylglyoxime in the presence of stannous chloride. Therefor, this reaction can be used for the determination of nitrate ion. This method was applicable to the determination of nitrate-nitrogen in the range of 0.1-3.5 ppm. The standard deviation was ±3.0% on an average absorbance of the 2.0 ppm nitrate-nitrogen solution. Many coexisting substances except copper (II) did not interfere in the determination of nitrate ion. The procedure is as follows : A sample solution (10 ml) containing less than 35μg of nitrate-nitrogen is placed in a 50-ml volumetric flask, 1 ml of 35% hydrochloric acid, 15 ml of 99.5% ethanol, 3 ml of 200-ppm rhenium solution, and 4 ml of stannous chloride solution are added, and the mixture is allowed to stand for 25 min after shaking. To this mixture, 6 ml of 1% dimethylglyoxime solution is added, and the whole is brought to 50 ml with water. The absorbance of the developed color is measured at 442 nm after about 25 min.
