agente conservante per cosmetici e farmaci

Per questo documento il full text online non moncler bambino saldi disponibile.

AbstractThe subject of this thesis involves the photolysis of the methylester of 4 hydroxybenzoate (methylparaben https://www.moncleroutlet-i.org , MP) in aqueous piumini moncler saldi solutions. The interest for this substance is due to moncler outlet online shop the fact that large quantities are released into the environment because of its widely used as bactericide in many cosmetic preparations and personal moncler donna hygiene. It was also demonstrated that moncler outlet trebaseleghe the MP has estrogenic activity and has been suggested a possible relationship between breast cancer and use of this substance. moncler outlet serravalle The thesis is a contribution to the characterization of the photophysical and photochemical behavior of MP in aqueous media, that characterization is part of the knowledge required to fully understand moncler outlet online uomo the impact on the environment and human health. have studied the photophysical behavior of MP measurements of quantum yield of fluorescence, phosphorescence and triplet excited state formation by sensitized delayed fluorescence. From these experiences he found a low value of fluorescence quantum yield (0.5%) while high values for both the relativistic quantum yield of phosphorescence (88%) and the quantum yield of formation of the triplet state (62.9%). then approached the study of the moncler saldi uomo mechanism of direct photolysis by determining the kinetics and degradation products of MP in aqueous solution in an atmosphere of air, oxygen and piumini moncler argon. The kinetics were followed initially by direct analysis UV Vis of the irradiated solution but the results are unreliable because of interference from absorption by some photo products. then repeated with the kinetic method based on HPLC UV to follow the disappearance of the MP as a function of irradiation time. The results clearly indicate that the presence of molecular moncler saldi outlet oxygen in the reaction slows down the process and suggest that the MP decomposition proceeds through the triplet excited state. I also made a preliminary analysis and qualitative photodegradation products using HPLC UV, HPLC MS and HPLC moncler bambino outlet MS MS, which allowed me to assume the structure of moncler saldi certain products and as a mechanism to bring the hydroxylation piumini moncler uomo of MP. piumini moncler outlet To mimic the natural environment have also studied the reaction of photodegradation of the MP with lamp NUV Vis in the presence of two photo moncler outlet sensitizers by determining the kinetics of disappearance of substrate. It was found that the MP is partially degraded with acid humic and Rose Bengal. I outlet moncler ran a couple of experiments of photocatalysis with TiO2 of MP by determining the kinetics and analyzing piumini moncler scontatissimi the products with chromatographic separation techniques and mass spectrometry as above. It is assumed that the degradation of MP is done through a process on the surface of the photocatalyst and is through a process of diffusion of oxidizing species in solution (hypothesis also supported by the analysis of total organic carbon TOC). HPLC MS analysis were shown some advanced oxidation products moncler outlet , which are plausible with moncler uomo the photo oxidation of phenol, a probable intermediate in the degradation of MP in these conditions. FF. NN.