The main goal of the project is to develop techniques for the reliable determination of middle-sized molecules in spent dialysates using selective and highly sensitive up-to-date luminescence methods either in vivo or in vitro. The in vitro techniques will include a substantial modification of the organic components by the modern methods of material technologies, including separation, enriching, incorporation of luminescent markers (e.g. rare-earth ion complexes), in order to increase the specific light yield and to improve other optical characteristics of various components, to increase the diagnostic selectivity and thus to optimize the duration and cost of the analysis in particular and of the medical procedure in general. The special methods will allow identification and quantification of the components possessing a diagnostic value. Their light emitting mechanisms will be clarified, using in several cases model substances. The establishment of the nature of complex organic components is an important scientific and applied task, since it may open new perspectives in the study of metabolism, the functioning of the kidneys, in the development of optical, including fluorescent, methods of analysis and control in nephrology, the synthesis of new fluorescent markers for wide application etc. The research will be performed in cooperation between the Institute of Physics and the Institute of Chemistry from Tartu University and AS LDIAMON.