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用二甲酚橙光度法测定铝时,酸度的影响小,据文献报道在pH=2.5～3.2时显色,且以EDTA作掩蔽剂来提高选择性。但络合物仅仅稳定10分钟,操作很不方便。经实验证明,当有适量乙醇存在时,不仅使显色反应更灵敏,且可进一步扩大显色的pH范围(由pH3.0～5.5扩大到pH3.0～6.5),同时还可使络合物的λmax由510nm移至515nm。该络合物形成后不被大量EGTA分解,并且至少稳定2小时。而锌、铜、铅、钴、镉等络合物能被EGTA即刻分解。当有抗坏血酸和邻菲罗啉存在时,一定量的铁、镍、钒等离子也无影响(相同条件下用EDTA退色制备参比液)。本文在抗坏血酸存在
When using xylenol orange photometric method for the determination of aluminum, the influence of acidity is small. It has been reported in the literature that when pH = 2.5 to 3.2, color is developed, and EDTA is used as a masking agent to improve the selectivity. However, the complex is only stable for 10 minutes, the operation is very inconvenient. Experiments show that when there is an appropriate amount of ethanol, not only the color reaction more sensitive, and can further expand the color range of pH (from pH3.0 ~ 5.5 to pH3.0 ~ 6.5), but also allows complex The λmax of the substance is shifted from 510 nm to 515 nm. The complex was not formed after extensive EGTA decomposition, and stable at least 2 hours. The complexes of zinc, copper, lead, cobalt and cadmium can be immediately decomposed by EGTA. When ascorbic acid and o-phenanthroline were present, a certain amount of iron, nickel and vanadium ions were also not affected (reference solution was prepared by fading with EDTA under the same conditions). This article exists in ascorbic acid