SELECTIVE AND SENSITIVE IN-VITRO DETECTION METHOD FOR ALUMINUM PHTHALOCYANINE PHOTOSENSITIZERS, USING LIQUID-CHROMATOGRAPHY AND DIODE-LASERINDUCED FLUORESCENCE

A combination of conventional-size liquid chromatography (LC) and visi ble diode-laser induced fluorescence (DIO-LIF) detection has been appl ied for the detection of photosensitizers used in photodynamic therapy . Of these photosensitizers, a mixture of disulfonated aluminum phthal ocyanines (AlPcS(2)) has been chosen as a model. First, the influence of pH and solvent on the spectroscopic properties of di- and tetrasulf onated aluminum phthalocyanine has been examined, indicating the prese nce of multi-step ionization equilibria and the formation of aggregate s. Direct fluorescence detection of AlPcS(2) is found to be unsatisfac tory. For biological samples, the introduction of LC showed clear adva ntages, especially for faeces extracts. A detection limit of 7 x 10(-1 2) M was found for AlPcS, (S/N = 3 for the major component) in both ra t urine and faeces extracts using the DIO-LIF system, which is 20-fold more sensitive than a conventional fluorescence detection system, in combination with chromatography.