Metodologia analítica para determinação de esteróis fecais em sedimentos por cromatografia líquida de alta eficiência

Abstract

The fecal sterols are considered important indicators of fecal contamination in aquatic environments. Organic compounds are hydrophobic and are associated with the particulate material and can be preserved for a long time with negligible degradation. The relationships between coprostanol and other sterols found in the environment are important to confirm the presence of domestic sewage into aquatic environments. The present work developed an analytical method for extraction, separation and determination of sterols coprostanol, epicoprostanol, cholesterol, cholestanol and sitosterol in sediment samples. Then applied the method in sediment samples collected from six streams in the city of Juiz de Fora. The method of analysis of the five sterols was optimized (High Performance Liquid Chromatography (HPLC) using reverse phase chromatography column octadecylsilane (C-18) with detection in the ultraviolet region. To optimize the separation of sterols by HPLC, the composition and flow of mobile phase for isocratic elution were optimized, as well as the wavelength of detection. Because sterols are not molar absorptivity in this spectral region, it was necessary to make the process of derivatization. For this, we tested two derivatizing reagents to increase the sensitivity of the method. Thus, it can separate and quantify the five fecal sterols. When you complete this step, we applied this methodology for studies of treatment samples. The result of this study allowed percentage recovery of analytes suitable. After treatment the sample was held optimized the procedure for derivatization of the extracts for analysis by HPLC. The concentrations of coprostanol in the sediment samples analyzed varied between 0.0050 and 14.48 µg.g-1. Except for the sample stream Farm Forest, all others were considered contaminated by feces using the parameters and evaluation criteria for this type of contamination.