The spectral properties of Pr (III) doped system with some biologically important alkaloids (i.e. atropine, brucine and caffiene) were investigated at different metal- ligand concentration and broad pH range (2 to 6). The analysis of oscillator strength values of the hypersensitive transition (3H4 3P2) and Judd-Ofelt intensity parameters were performed in order to determine the formation of metal-ligand coordination complex and the type of bonding.
