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一、前言测定铜合金中铁时,在大多数的分析方法中,由于铜离子的严重干扰,必须进行分离,如电解除铜后,用硫氰酸盐比色,虽然准确度很高,但是手续麻烦,还需电解设备,和目前采用络合滴定其他元素的方法,不能配合起来;也有采用硫氰酸铵,亚硫酸使铜成硫氰化亚铜沉淀分离后,再以硫氰酸铵比色测定【1】,但在铁合量较低时,不够稳定;也有采用氢氧化铵分离铜后,用重铬酸钾滴定【2】.此法不但手续麻烦,而且有锑存在时,要产生严重干扰;也有不分离铜,直接比色的,如用EDTA掩蔽其他离子,邻菲罗啉直接比色【3】【4】,但此方法很不容易掌握.H·J·Claley等提出【5】,以Fe-EDTA-H_2O_2的紫色络合物,直接测定铜合金中的铁,不需要任何分离手续.经过我们多次试验,证明该法不但非常稳定,重现性很好,而且很快速,灵敏度也很高,容易掌握.
I. INTRODUCTION In the determination of iron in copper alloys, in most analytical methods, it must be separated due to the serious interference of copper ions. For example, thiocyanate colorimetric after electrolytic copper removal, though the accuracy is very high, but the procedure Trouble, but also electrolysis equipment, and the current complexation titration with other elements of the method can not be used together; there are also used ammonium thiocyanate, copper sulphite bisulfite precipitate separation, and then ammonium thiocyanate ratio Color determination [1], but in the iron content is low, not stable enough; also use ammonium hydroxide separation of copper, with potassium dichromate titration [2] This method is not only troublesome procedures, and the presence of antimony Have serious interference; also have no separation of copper, direct colorimetric, such as the use of EDTA to mask other ions, orthophenanthroline direct colorimetric [3] [4], but this method is not easy to grasp .H.J.Claley et al [5], to Fe-EDTA-H_2O_2 purple complexes, direct determination of copper alloy in the iron, without any separation procedures.After many of our tests, the method proved not only very stable, reproducible, and Very fast, high sensitivity, easy to grasp.