摘要：Lanthanum as a member of lanthanides group represents widely used element, which biological properties and interactions with biomolecules are still almost unknown. Due to industrial utilization of lanthanum compounds, but also due to their applications in medicine, lanthanum poses potential ecological risk. Therefore, it is necessary to look for new methods of its determination in biological samples and determine possible impact on the organisms. As the most suitable, especially because of difficultness of its determination by the use of other methods, such as atomic absorption spectroscopy, appear spectophotometric methods based on formation of coloured complexes. Aim of this submitted work consisted in optimization of spectrophotometric method based on the formation of coloured complexes with the Arsenazo III reagent and its application in determination of free, it means bio-available lanthanum(III) ions in samples of water.
