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钒、钛、锰、铬等元素,对EDTA容量法测定铝、钙、镁都有不同程度的干扰.钛定量干扰测定铝.钒(V)与PAN或二甲酚橙指示剂生成红色络合物,对测定铝的终点判断带来严重困难.锰使滴定铝的终点提前使结果偏低.铬(Ⅲ)和EDTA形成紫色络合物,影响铝、钙、镁滴定终点判断.当钛量高时,由于水解产生的沉淀吸附钙离子,使结果偏低.锰封闭滴定钙的指示剂.pH=10时,微克量的钛就使铬黑T指示剂封闭.钒(V)和钒(Ⅳ)在络合滴定镁时,使铬黑T指示剂终点返回.锰(Ⅱ)在 pH=10时和镁一起被EDTA络合,使结果偏高.
Vanadium, Titanium, Manganese, Chromium and other elements have different levels of interference with EDTA volumetric method for the determination of aluminum, calcium and magnesium. Titanium quantitative interference determination of aluminum. Vanadium (V) and PAN or xylenol orange indicator red complex The determination of the end point of aluminum caused serious difficulties.Mn manganese led to the end of the titration of aluminum in advance so that the result is low.Chromium (Ⅲ) and EDTA form a purple complex, affect the aluminum, calcium and magnesium titration endpoint judgment .When the amount of titanium High, due to the precipitation of calcium generated by hydrolysis, the result is low. Manganese closed titration of calcium indicator .pH = 10, the micrograms of titanium black chrome black T indicator closure. Vanadium (V) and vanadium (V) IV) When complexing titration of magnesium, the end of the chrome black T indicator is returned Manganese (II) is complexed with magnesium at pH = 10, resulting in a high result.