engleski

DETERMINATION OF QUANTUM YIELDS FOR THE PHARMACEUTICALS PHOTOLYSIS IN AQUEOUS SOLUTION

Pharmaceuticals are being continuously introduced into the environment like excreta, disposal of unused drugs or as a result of industrial processes. However, the main points of pharmaceuticals release into the environment are wastewater treatment plants. Once released into the aquatic environment, pharmaceuticals may undergo different degradation processes. Photolysis might be an important degradation process for light-sensitive pharmaceuticals, such as sulfonamides since they have aromatic rings, heteroatoms, and other functional chromophore groups that can absorb solar radiation. Sulfonamides are one of the commonly used families of antibiotics in veterinary medicine, although they were frequently applied as human medicines to treat many kinds of infection. The aim of this study was to determine the quantum yield of two sulfonamides (sulfadiazine and sulfamethaxazole), which is used as input to the appropriate computer program for prediction of the pharmaceuticals half-life in the environment. Quantum yield is defined as the ratio of the number of reactant consumed or the number of generated product and the number of photons absorbed by substances. Since the rates of photochemical reactions are affected by the intensity of the source of irradiation, this intensity must be known. Actinometry provides the way by which intensity can be determined. Potassium ferioxalate as the most reliable and practical actinometer was used to determine the lamp intensity of the Suntest CPS+ simulator (300-800 nm) which is used as a source of artificial sunlight. Irradiated solutions of sulfonamides were analyzed by both LC-MS/MS, which was performed with an Agilent 6410 triple-quadrupole mass spectrometer coupled with an Agilent Series 1200 HPLC system and spectrophotometry. Spectrophotometry was performed using a Perkin Elmer UV/Vis spectrophotometer LAMBDA 25. On the basis of obtained lamp intensity and change in the concentration of sulfonamides during the irradiation, the quantum yields of sulfadiazine and sulfamethoxazole photolysis were calculated.

quantum yield; sulfonamides

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