Otimização e validação de metodologias analíticas em GC-MS aplicadas à biodegradação de poluentes orgânicos persistentes e óleo essencial de pimentas

Abstract

Recently, a large number of compounds have been synthesized in order to bring comfort and convenience to everyday life. These products, however, produce a large amount of daily waste that are released into the environment causing great inconvenience to the population. Higher concerns focus on the compounds known as persistent organic pollutants (POPs) that have brought serious problems of persistent contamination for decades. POPs are compounds of difficult degradation, that can lead to the bioaccumulation in the food chain and intoxication of the men and animals exposed to them. It is known that insects can acquire resistance to xenobiotics due to their association with microorganisms, which have their own enzymatic mechanisms for biotransformation of these compounds. Thus, in a first step, the present work proposed the development of an analytical method to study the biodegradation of three classes of POPs: polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and dioxins. Microorganisms used in this research were all isolated from Diabrotica speciosa, an insect present in several Brazilian agricultural crops. All POPs were analyzed by gas chromatography and mass spectrometry, whose method was validated by observing variables such as linear range, matrix effect, accuracy and intra- and inter-day accuracy, limit of detection and quantification. The validation followed the standards established by Anvisa, in accordance with Resolution RDC No. 166/2017. Due to the high adsorption of the samples components into GC equipment, occurring in decreased sensitivity. Moreover, this study also presents the optimization of bacterial growth and different extraction techniques for the target analytes. For bioremediation processes, Burkholderia gladioli was the most prominent bacteria for HPAs, while Serratia marcescens was better for dioxins. These bacteria degraded 18.3 and 22.3%, respectively, of the applied mass in relation to the control in seven days experiment. In a second stage, this work also proposed the development a method of peppers essential oils analysis. The Principal Component Analysis (PCA) of volatile compounds of seven Capsicum peppers, submitted to soxhlet extraction, hydrodistillation and headspace analysis, showed a great similarity between Bode pepper and Biquinho pepper (Capsicum chinense). Cumari of Pará, also belonging to the species Capsicum chinense, was the most differentiated pepper in comparison all those analyzed. Analysis of volatile compounds extracted by hydrodistillation technique and headspace analysis showed the highest number of compounds in relation to the soxhlet extraction,134, 110 and 79 signs respectively. The analysis of the compounds obtained by hydrodistillation showed signals with higher intensity and less dispersion of data, which reflected a greater quality of data generated for PCA. The profile of the essential oil obtained by the soxhlet extraction showed intense peaks for the compounds capsaicin and dihydrocapsaicina, whereas the 3,3-Dimethylcyclohexanol compound stood out as the most intense signal in the analyzes obtained by hydrodistillation and headspace. Thus, this study stands out for contributing to the expansion of technical-scientific knowledge from the environmental chemistry area to the natural products chemistry area showing the techniques versatility that employs GC-MS equipment.