RAPID PHOTOMETRIC DETERMINATION OF THE SUM OF RARE EARTHS

Compounds of rare earths and some other elements with arsenazo were investigated. Spectral characteristics of the solutions of these compounds were studied; molar extinction coefficients and equilibrium constants of the reactions of complex formation were found. It was established that the sensitivity of colorimetric reactions of rare earths with arsenazo, the stability of compounds formed, and their extinction spectra are interdependent. A method of preparing calibration curves for the determination of rare earths was suggested. The possibility of the quantitative colorimetric determination of the sum of rare earths in natural materials was established on the basis of the similarity of chemical and optical characteristics of the compounds of rare earths with arsenazo. A rapid method for the quantitative photocolorimetric determination of the sum of rare earths with arsenazo was suggested. (auth)