| 摘要 |
PURPOSE: To quantitatively analyse nitrates with out difficulty even in a salty sample, by carrying out simple and highly sensitive quantitative analysis of nitrate ion. CONSTITUTION: A sample is mixed with resorcinol and a mixture of sulfuric acid and phosphoric acid, and a specified amount of chloride ion is added. In the reaction, the resorcinol works as a color reagent in the presence of a concentrated mixture of mineral acids and the ratio of the mixture of sulfuric acid and phosphoric acid is preferably 9:1 in the volume ratio. The concentration of resorcinol is preferably 0.12-0.16wt.% in the mixture for measurement and the quantity of the chloride ion is 10-30g/l. The quantitative analysis of nitrate ion is carried out by making the mixture of resorcinol and the chloride uniform in the mixture of sulfuric acid and phosphoric acid and adding or mixing a sample solution to be determined to the resultant mixture. The reaction is finished in 2-3 minutes and evaluated by spectrophotometry at 505nm. In the case nitrates exist, the reaction sensitivity is high and 0-15mg/l of nitrates in sea water can be determined using a measurement cell with,. for example, 1cm length. |
