论文部分内容阅读
本刊1976年第2期刊登了有关硫氰酸盐吸光度法测定钼的几篇文章。这些方法各有特点,观点有相同之处,也有明显的差异。现将其中有关反应机理的问题谈谈我们的粗浅认识。一、铁或铜离子对钼显色的影响: 用硫氰酸盐吸光度法测定钼,须有大过量于钼的铁离子存在才能使钼的显色趋于完全,从而达到较高的灵敏度和稳定性,已为分析者所熟知。资料中认为,欲获得钼的最大回收,铁钼比100:1是需要的。周南同志指出,测定40微克MoO_2~(2+)离子时,铁含量宜控制在15～24毫克或25～35毫克范围内。并进一步研究了铁离子存在促进钼显色反应的机理,认为MoO_2~+和Fe~(2+)分别与SCN~-中的氮原子和硫原子起
This issue No. 2, 1976 published a few articles on thiocyanate absorbance determination of molybdenum. These methods have their own characteristics, points of view are the same, there are obvious differences. We will now talk about our superficial understanding of the reaction mechanism. First, the iron or copper ions on the color of molybdenum: thiocyanate absorbance method for the determination of molybdenum, there must be a large excess of molybdenum iron ions exist in order to molybdenum color development tends to be complete, so as to achieve high sensitivity and Stability is well known to analysts. Data that, in order to obtain the maximum recovery of molybdenum, iron and molybdenum ratio of 100: 1 is needed. Comrade Zhou Nan pointed out that when measuring 40 micrograms of MoO 2 2+ ions, the iron content should be controlled within the range of 15-24 mg or 25-35 mg. Furthermore, the mechanism of promoting the color reaction of molybdenum with ferric ions is further studied. It is believed that MoO_2 ~ + and Fe ~ (2+) react with nitrogen and sulfur atoms in SCN ~ -