【摘要】 采用预蒸馏纳氏试剂吸光光度法测定污水中的氨氮，以Ｈ３ＢＯ３ 溶液作吸收剂时，有色胶体的稳定性较差，加入ＮａＯＨ溶液可提高胶体的稳定性。当ＮａＯＨ 溶液（１ ｍｏｌ／Ｌ）与Ｈ３ＢＯ３ 溶液（２ ％） 的体积相同时，有色胶体稳定时间最长。加入胶体保护剂聚乙烯醇（ＰＶＡ） 可进一步提高胶体的稳定性和测定准确度。对Ｈ３ＢＯ３ ，ＮａＯＨ 和ＰＶＡ 的影响规律进行了研究，提出了最佳实验条件：以２％ Ｈ３ＢＯ３ 溶液作吸收液，１ ｍｏｌ／ＬＮａＯＨ 溶液１０ ｍＬ，罗谢尔盐溶液１．００ ｍＬ，５％ 聚乙烯醇０．１６ ｍＬ，纳氏试剂１ ．００ ｍＬ，反应１０ ｍｉｎ。该方法的最低检出限为０．０１５ ｍｇ／Ｌ，回收率为９８ ．６％ ～１０３％ ，适用于环保站、化工厂进行的常规分析更多还原

【Abstract】 In the experiment of NH\-3\|N contents determination by using predistillation\|Nessler’s reagent spectrophotometry, the stability of colloid solution is poor when 2% H\-3BO\-3 solution is used as adsorbent of NH\-3. But it can be improved by adding NaOH solution. The existing time of colloid solution is the longest when the volume of NaOH solution (1 mol/L) is as more as H\-3BO\-3 solution (2%). The stability of colloid solution and the accuracy of NH\-3\|N determination can be further improved with the addition of polyvinyl alcohol (PVA) as the colloid protectant. Affecting behaviors of H\-3BO\-3, NaOH and PVA are studied. The optimum test conditions are as follows: 10 mL of 2% H\-3BO\-3, 10 mL of 1 mol/L NaOH, 1 mL of Rochelle salt solution, 0.16 mL of 5% PVA, 1 mL of Nessler’s reagent solution, and the reaction time is 10 min. The detection limit is 0.015 mg/L, and the recovery of NH\-3\|N is 98.6%～103%. The method is suitable for conventional analysis of NH\-3\|N in environmental monitoring centers or factories.更多还原