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我们采用乙酰丙酮掩蔽镁,以二甲酚橙(XO)-溴化十六烷基三甲铵(CTMAB)作指示剂,在pH=10.5氨性缓冲溶液中,用EDTA滴定氧化钙和氧化镁,终点敏锐。适量铝、硅酸不干扰测定。Bi(0.2mg,下同)Cu(0.1),在三乙醇胺掩蔽下,Fe(15)不影响测定。NiZn 被滴定,应掩蔽或分离。方法可应用于石灰石、粗盐等试样中钙镁的测定。用于高镁低钙试样,终点尤为敏锐。一测定方法石灰石(0.8～1g),粗盐(50～60g),合成试样(粗盐50g+MgO 0.2000g)等试样按一般方法进行分解,制成1000毫升试样溶液。
We masked magnesium with acetylacetone, titrated calcium and magnesium oxide with EDTA using xylenol orange (XO) - cetyltrimethylammonium bromide (CTMAB) as an indicator in a pH = 10.5 ammoniacal buffer solution, End sharp. Appropriate amount of aluminum, silicate does not interfere with the determination. Bi (0.2mg, the same below) Cu (0.1), Fe (15) does not affect the determination under triethanolamine masking. NiZn is titrated and should be masked or separated. The method can be applied to the determination of calcium and magnesium in limestone, crude salt and other samples. For high-magnesium low-calcium samples, the end point is particularly acute. A measurement method Limestone (0.8 ~ 1g), crude salt (50 ~ 60g), synthetic samples (crude salt 50g + MgO 0.2000g) and other samples were decomposed according to the general method, made of 1000 ml sample solution.