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系统研究了酸性铬蓝Ｋ（ＡＣＢＫ） 与钙镁同时作用的显色体系，采用Ｃａ２＋ 、Ｍｇ２＋ 摩尔浓度相同的混合标准溶液试验了影响该显色体系的灵敏度和稳定性的各项因素，确定了最佳操作条件。试验表明，在ｐＨ＝１０－２ 的氨—氯化铵缓冲介质中，Ｃａ２＋ 、Ｍｇ２＋ 离子均可与ＡＣＢＫ 显色剂形成１∶１ 的配合物，在４６８ ｎｍ 波长处，两种配合物存在一等摩尔吸收点，对应于该点的等摩尔吸光系数ε＝７－４×１０３ Ｌ／（ｍｏｌ·ｃｍ） ，在此波长及最佳操作条件下，Ｃａ２＋ 和Ｍｇ２＋ 的总含量在０ ～３ ×１０ －５ ｍｏｌ／Ｌ浓度范围内符合比耳定律。在试验了１３ 种常见共存离子干扰的基础上将本法用于６ 种水样的硬度测定，回收率在９６－５％ ～９９－９ ％ 之间，结果与ＥＤＴＡ 滴定法颇为一致。
The color system of acid chrome blue K (ACBK) and calcium and magnesium were studied systematically. The factors affecting the sensitivity and stability of the color system were tested by mixed standard solution with the same molar concentration of Ca2 + and Mg2 + Best operating conditions. The results showed that Ca2 + and Mg2 + ions could form a 1: 1 complex with ACBK reagent in ammonia-ammonium chloride buffer solution at pH = 10-2. At 468 nm, two complexes existed Equimolar absorption point, corresponding to the equimolar absorption coefficient ε = 7-4 × 103 L / (mol · cm) at this point, the wavelength and under the best operating conditions, the total content of Ca2 + and Mg2 + in 0 ~ 3 × Beer’s law is in agreement with the 10 -5 mol / L concentration range. The method was applied to the hardness determination of six kinds of water samples with the recovery of 96-5% ~ 99-9%. The results were in good agreement with the EDTA titration method.