A Precision Spectrophotometric Method for Determining U, Pu, Nd, and Rh, Based on the Internal Standardization Principle

Abstract

The principle of spectrophotometric determination of the concentrations of elements based on internal standardization of the sample analyzed is presented. As the function of the parameter to be determined, namely, the concentration of element in solution, we suggest the ratio of two signals, one of which is the light intensity at the wavelength of an absorption band of an element being analyzed and the other is the reference signal of a sample, namely, the light intensity at a wavelength at which the solution of the element being analyzed is virtually transparent. The analysis is performed with a specially designed two-channel spectrophotometer in which fairly strict correlation between the signals is provided by measuring their intensities virtually simultaneously, with the same detector and amplification system. The signals are isolated by a monochromator and interference light filters. The spectrophotometer operation control and data processing are effected by a PC. The metrological characteristics of the method proposed were experimentally determined. The relative root-mean-square deviation of the uranium, plutonium, neodymium, and rhodium concentrations in pure solutions of their salts was within 0.1-0.25%.