Indirect determination of trace amounts of lithiumvia complex with iron by X-ray fluorescence spectrometry

Abstract

The extremely low fluorescent yield and long-wavelength characteristic radiation are the major limitations for direct XRF determination of the elements of low atomic numbers. In the case of lithium, the determination of this element by X-ray fluorescence spectrometry (XRF) is not possible. Thus, an indirect method for the determination of lithium by X-ray fluorescence spectrometry was proposed. The method is based on the determination of lithium through iron in the potassium lithium periodatoferrate(III) complex. The complex was collected on the membrane filter and the Fe K_α line was measured by XRF. The optimum conditions for LiKFeIO₆ complex formation and XRF measurement were studied. A good ratio of lithium to iron (1 to 8) and a sensitive Fe K_α line give the possibility to determine a low lithium amount. The proposed method allows the determination of 20 µg of lithium collected on a filter. The validity of the proposed method was verified with certified lithium ores. The agreement between XRF analysis and certified values is satisfactory and indicates the usefulness of the carried out method.