| 摘要 |
PROBLEM TO BE SOLVED: To enhance the preservability of liquid DPD (diethyl-p-phenylene diamine) reagent. SOLUTION: The acid concentration of the liquid DPD reagent is increased more than 0.072 N (normal value). The concentration is preferably set within a range of 0.14-3.0. Phosphate buffer solution of which the pH is biased from 6.5 to alkaline side is used when the residual chlorine concentration is measured. Thereby, the liquid DPD reagent can be preserved for longer time than a conventional liquid DPD reagent. Even when liquid DPD reagent with a high acid concentration is used, the pH of the sample water obtained by mixing the phosphate buffer solution with the liquid DPD reagent can be adjusted to about 6.5 and the residual chlorine can be measured without trouble. COPYRIGHT: (C)2003,JPO
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