Desenvolvimento de métodos cromatográficos para análises de antimicrobianos em amostras complexas / Development of chromatographic methods for analysis of antimicrobials in complex samples

AUTOR(ES)
FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

23/04/2012

RESUMO

This work describes the development of chromatographic methods in combination with microextraction techniques for the determination of parabens in cosmetic and human milk samples and of rifampicin in plasma samples. The design of a molecularly imprinted extraction phase for the solid-phase extraction (SPE) analysis of parabens in human milk samples is also reported. Chapter I describes the evaluation of the stir bar sorptive extraction (SBSE) in combination with liquid chromatography (LC) with UV detection (LC-UV) for the analysis of parabens in cosmetics aiming at quality control. The SBSE variables such as extraction time, temperature, pH of the matrix, ionic strength, and desorption conditions have been optimized, in order to establish the parabens partition equilibrium in a short analysis time. The linear range of the SBSE/LC method lay from LOQ to 2.5 µg. mg-1, with a coefficient of determination higher than 0.993. The interday precision of the SBSE/LC method presented a coefficient of variation lower than 5%, and the accuracy ranged from 90 to 99%. The effectiveness of the proposed method for the analysis of commercial cosmetic products such as body creams, antiperspirant creams, and sunscreens has been proven. Therefore, the combination of SBSE with liquid desorption, followed by LC analysis, provides a simple, and selective tool for the analysis of parabens in cosmetic products using minimized volume of organic solvent as well as very small amount of the target sample. Chapter II presents the development of a molecularly imprinted extraction phase for the SPE analysis of parabens in human milk samples. The molecularly imprinted polymers, which are synthetic materials based on biomimetic systems, were synthesized by the sol-gel technology in the presence of the template (benzilparaben). After template removal, selective cavities (benzilparaben) were revealed for parabens selective extraction. The linear range of the SPE/LC method lay from LOQ to 150 ng. mL-1, with a coefficient of determination higher than 0.992. The interday precision of the SPE/LC method presented a coefficient of variation lower than 13%, and the accuracy ranged from 86 to 117%. The effectiveness of the proposed method for the analysis of human milk samples has been demonstrated. According to the evaluated analytical validation parameters, the SPE/LC-UV method is suitable for the analysis of parabens in human milk samples. Chapter III depicts the evaluation of solid-phase microextraction in the capillary (in-tube SPME) in combination with liquid chromatography (LC) with UV detection (LC-UV) for the analysis of rifampicin in plasma samples for therapeutic drug monitoring. The in-tube SPME/LC method was linear over the LOQ (0.1) to 100 g. mL-1 range, with a linear coefficient value (r2) of 0.998. The inter-assay precision presented coefficient of variation 2%, and the accuracy ranged from 83 to 92%. The effectiveness and practicability of the proposed method have been by analysis of plasma samples from ageing patients undergoing therapy with rifampicin. The in-tube SPME/LC method allowed for automated continuous sample preparation (extraction, concentration, desorption, and injection of analytes) and minimized the analysis time as well as the volumes of organic solvent and biological fluid.

ASSUNTO(S)

cromatografia líquida liquid chromatographic moleculary imprinted polymers parabenos parabens polímeros molecularmente impressos. rifampicin rifampicina

ACESSO AO ARTIGO

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