Determination of palladium in nuclear-waste samples by inductively coupled plasma emission-fluorescence spectrometry

Abstract

The determination of palladium in sample solutions of nuclear waste by inductively coupled plasma (ICP) optical emission spectrometry with a 0.5-m monochromator is hindered by severe spectral interference that occurs at all the analytically useful wavelengths of palladium. Interferences from argon, yttrium, zirconium, samarium and neodymium lines have been experienced with the palladium lines at 363.47, 324.27, 340.45 and 360.95 nm. In order to overcome these interferences a spectrometer of high resolution is required. This precludes the use of a multi-channel spectrometer and indicates the application of a high-resolution scanning monochromator. In this paper we show that a simple and effective alternative approach to the problem is offered by combination of the ICP emission characteristics with the spectral selectivity of atomic-fluorescence spectrometry. Measurement of the palladium atomic fluorescence at 363.47 nm from a sample atomised in an argonshielded air - acetylene flame, excited by the emission of a pure 5000 µg ml^–1 solution of palladium fed into the ICP torch, allows for the precise and accurate determination of palladium, with no problems due to scattering. In addition, the palladium concentration in the samples is such that the ICP - resonance monochromator technique could be quickly and effectively used with no sample dilution, provided that sufficient sample is available and that radioactivity is at a tolerable level.