偶氮氯膦-pA分光光度法及催化光度法测定痕量贵金属元素(英文)

Tracing Noble Metal-chlorophosphonazo-pA Complexes Determined by Methods of Conventional and Catalytic Spectrophotometries

报道了偶氮氯膦-pA用于痕量贵金属元素钌、铑、钯、锇、铱、铂的测定研究及应用。偶氮氯膦-pA与贵金属钯在硝酸介质中表现为显色反应,建立了光度法测定痕量钯的新方法;而偶氮氯膦-pA在微量贵金属离子钌、铑、铂、锇、铱存在下与氧化剂(高碘酸钾、溴酸钾)的催化褪色反应,则建立了测定这些金属元素的催化分光光度新方法。动力学分析建立了相关的线性方程。本文考察了该系列反应的最佳条件、如反应时间、吸收曲线、检出限及线性范围等。此类方法可直接在水溶液中进行,简便快速,灵敏度高,用于贵金属精矿、催化剂等样品中微量铂系元素的测定,结果满意.

In this paper,the conventional spectrophotometric determination of trace Pd（Ⅱ） using the chlorophosphonazo-pA（CPA-pA） chelated colour reaction in nitric acid,and the dynamic catalytic spectrophotometric determinations for traces Ru,Rh,Os,Ir,and Pt were studied.A theoretical kinetic analysis indicated the fading obeys an exponential function,which was used to predict the feasibility and how to acquire the most accurate data,i.e.to select the reaction time within the linear portion of the exponential fading curve.Results revealed the overall detection limits to be within 10^-2～10^-3g/mL.Briefly,CPA-pA was used to chelate the metals of interest to produce colored chromophoric complexes that fade in the presence of the oxidants KIO4（or KBrO3）/H2SO4 plus noble metallic ions of interest,the fading rates of the coloration were found to be highly and inversely correlated with the concentration of catalytic etallic content present.Based on this,a novel dynamic catalytic spectrophotometric method with high sensitivity and appreciable selectivity feasible for determination of trace amounts noble metals were developed,the accuracy of which depends on the time period of reaction which is imperatively required to be determined in the linear region of fading curves.