二溴硝基偶氮氯膦用于微量铂系元素测定的应用研究

Application of DBNCPA Fading Reaction to Determination of Trace Pt

作为不对称变色酸双偶氮试剂的二溴硝基偶氮氯膦与金属钯可发生显色反应,而与同属铂系元素的其他五种金属的显色反应并不明显;可是在高碘酸钾、溴酸钾等氧化剂的存在下,它们却能使二溴硝基偶氮氯膦发生催化褪色反应.从而建立了用直接光度法测定钯和用催化光度法测定钌、铑、锇、铱、铂的微量分析新方法.本文考察了该系列水相中直接测定铂系元素反应的最佳条件,并提出了贵金属样品中微量铂系元素的测定方法.

DBNCPA of asymmetry acid bis--diazo reagent have the color reaction with the metal palladium,but have not obvious color reaction with other five kind of metal elements of the platiniridium. The fading reaction of KIO4 （KBrO3） with DBNCPA in acid medium can be realized only under catalytic action of trace Ru,Rh,Os,Ir and Pt. There is better linear relationship between fading degree and Pt content. Authors have investigated the optimum condition of the reaction and established catalytic spectrophotometry of trace Pt. The detection limit is 0.01μg· 10mL^-1 and Beer＇s law is obeyed in the range of 0.1-1.0μg·mL^-1. The method offers the advantages of simple, accurate,and better selectivity,and has been applied to the determination of trace Pt in refined precious metals ores.