Separation and direct detection of heavy lanthanides using new ion-exchange chromatography: fast Fourier transform continuous cyclic voltammetry system

In this study, possibilities of heavy lanthanides (Ho3+, Er3+, Tm3+, Yb3+, and Lu3+) separation on Nucleosil 100-5-SA, an ion-exchange column, was investigated. Separation of lanthanides was carried out using an isocratic program of α-hydroxyisobutyric acid (HIBA) eluent. Fast Fourier transform continuous cyclic voltammetry (FFT-CCV) at a gold microelectrode was used as the detection method. Simplicity, high precision and accuracy, time efficiency, and being economic are advantages of the developed technique in comparison with the previous reported ones. In addition, removal of oxygen from the test solution is not required, the detection limit is suitable and the technique is fast enough for determination of compounds in a wide variety of chromatographic methods. The waveform potential was continuously applied on an Au disk microelectrode (12.5 μm in radius). The influence of HIBA concentration as well as pH of eluent was optimized. The best performance of the method was obtained at pH of 4.0, scan rate of 30 V s−1, accumulation potential of −300 mV, and accumulation time of 0.3 s. The proposed method displays a linear dynamic range of 140 and 18,000 μg L−1 and a detection limit of 50 μg L−1. Precision, inter-day precision, and accuracy of the assay were reported too. A comparative evaluation of heavy lanthanides distributed in a sophisticated monazite and xenotime minerals solutions was carried out using both FFT-CCV, and inductively coupled plasma-atomic emission spectrometry (ICP-AES).