甲基橙褪色光度法测定铜合金中锡

Spectrophotometric determination of stannum in copper alloy based on fading reaction of methyl orange

在盐酸介质中,锡(Ⅱ)能使甲基橙还原褪色,且褪色的程度和锡的量有关,据此建立了测定锡?的光度分析方法。实验表明,在最大吸收波长514nm处,表观摩尔吸光系数为2.18×104L·mol-1·cm-1,相关系数为0.999 4,锡(Ⅱ)的量在20～100μg/25mL范围内服从比尔定律,方法的检出限为0.8μg/mL。方法用于锡磷青铜、磷青铜合金中锡的测定,测定值与认定值相符,其相对标准偏差在1.3%～2.1%,回收率为97%～104%。

A novel method for the determination of stannum was established.It was based on the fading reaction of methyl orange deoxidation by Sn（Ⅱ） in the medium of HCl acid.The decrease in colour was directly proportional to the amount of stannum.It was found that the maximum absorption was at 514 nm.The apparent molal absorptivity was 2.18×104L·mol-1·cm-1,the correlation coefficient was 0.999 4,and the linear range was 0 to 100 μg/25 mL.It has been proved that the method was simple,selective and repeatable for the determination of stannum in phosphor bronze and Sn-P bronze samples.The measured value was consistent with the standard values with RSD（n=6） of 1.25%-2.14 % and the recoveries wore 97%-104%.