Parabens are neutral esters derived from p-hydroxy-benzoic acid and at low concentration (0.016 to 0.4%) they inhibit the development of microorganisms in cosmetic products. In the skin, the esterase enzyme hydrolyses the parabens present in cosmetics of topical use. However, incomplete hydrolysis may occur in the presence of large amounts of parabens, wich may accumulate in the human body or even cause allergic dermatitis in sensitive individuals. Although regulatory organizations have authorized the use of parabens, more comprehensive studies are necessary to determine the true consequences of the potential damage caused by the daily exposure to parabens present in cosmetics. Biological fluids cannot be inserted into LC-MS/MS systems in their physiological state because of their complexity. They present interfering compounds, specially proteins, which can suppress the ionization of the analytes during ionization under pressure (API) (LC-MS analyses). As a consequence, the interferents elute with the analytes during the chromatographic separation or irreversibly adsorb onto the analytical column. This changes the analyte retention times, causes the column death and raises analysis costs. Solid Phase Extraction (SPE) is a liquid-solid separation technique that uses extraction devices in the solid phase. The complexity of plasma samples and the presence of parabens and the small amount in these matrices requires the development of more selective SPE extraction phases to enhance the selectivity and specificity of the chromatographic method. Molecularly Imprinted Polymers (MIP) are synthetic materials with molecular recognition properties based on biomimmetic systems that are similar to specific enzyme-substrate or antigen-antibody systems.This project aims to develop a molecularly imprinted phase extraction for the solid phase extraction of parabens in plasma samples, for analyses in Liquid Chromatography coupled to tandem Mass Spectrometry.
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