| 摘要 |
PURPOSE:To carry out a rapid and highly accurate measurement of Cl<-> in a very small amt., by obtaining a quantity of Hg(NO3)2 consumed during the color change of an organic-solvent layer from yellow to purple due to Hg(NO3)2, after adding diphenylcarbazone and the org. solvent to a water solution containing Cl<->, and adjusting the pH value by incorporating nitric acid in it. CONSTITUTION:1ml solution in which 0.1g diphenylcarbazone indicater is dissolved in 100ml special-grade alcohol, 100ml sample water containing Cl<-> (if >=0.5mg Cl<-> is contained, it is diluted), 3ml 0.15N HNO3 solution, and 1ml org. solvent such as toluene or the like are mixed, 0.00141N Hg(NO3)2 solution is dropped under stirring, and the quantity of Hg(NO3)2 consumed during the color change of the org. solvent layer from yellow to purple is obtd. (under the stirring, the org. phase can be seen at the V-shaped swirling part). By this method, Cl<-> at the low concentration down to 0.05ppm can be measured with a 10-20 fold higher sensitivity in <=10min, than the conventional method using Hg(NO3)2. |
