过量二甲酚橙隐色分光光度法测定铜的研究

The Spectrophotometric Determination of Micro Amounts of copper by Hiding Colour of the Excessive Xylene Orange

在ｐＨ９．９的ＮＨ３·Ｈ２Ｏ—ＮＨ４Ｃｌ介质中，二甲酚橙与Ｃｕ２＋形成稳定的紫红色络合物，用Ｈ２Ｏ２为隐色剂可以隐去过量显色剂的颜色，从而消除高色度背景的影响．络合物的最大吸收波长为５８０ｎｍ．摩尔吸光系数为４．９×１０４Ｌ／ｍｏｌ·ｃｍ，Ｃｕ量在０～０．４ｕｇ／ｍｌ范围服从比尔定律．方法已应用于测定矿样中的Ｃｕ．

Copper(Ⅱ)reacts with Xylene Orange to form a stable red complex in NH3H2O NH4Cl buffer solution(pH 9.9).The precision and sensititv are increased by hiding the background colour of the excessive xylene orange with H2O2.The maximun absorption of complex is at 580nm.The molar absorptivity is 4. 9×104 L/moL·cm.Beer's law is obeyed in the range 0-0.4μg/ml of copper.The method has been applied to the determination of micro amount of copper in ores with satisfactory results.