Desenvolvimento de método automatizado para investigação dos marcadores biogeoquímicos, hidrocarbonetos policíclicos aromáticos, em sedimentos dos recursos hídricos urbanos de Juiz de Fora - MG por HS-SPME-GC/MS

Abstract

In this work, an automated extraction method to determine 26 polycyclic aromatic hydrocarbons (PAHs) of which 8 are priority PAHs, in surface sediment samples from urban water resources in the Juiz de For city, MG, using gas chromatography coupled to mass spectrometry detection, with automated headspace solid phase microextraction was optimized. Eleven samples were collected in the city, in which three of them were from resources used to water abstraction to supply the population. The analysis parameters were optimized using experimental designs, which indicated the optimal condition using 5 g of sample mass, 5 mL of saline solution volume, 53.2 min for the extraction time, stirring at 350 rpm, 80 °C, 5 minutes of sorption and 1 minute for desorption. The linear interval of calibration curve for each PAH ranged from 10 to 40 ng g-1 and the Pearson correlations for all the compounds were above 0.98. The detection and quantification limits values ranged from 0.13 to 0.46 ng g-1 dry weight and 0.42 to 1.52 ng g-1 dry weight, respectively. The mean recoveries of the spiked samples ranged from 74 ± 16 % (acenaphthylene) to 98 ± 5 % (fluoranthene) and 84 ± 8 % (retene) to 119 ± 6 % (9-methylanthracene) for the spiked blanks. The total concentration of PAHs in the samples ranged from 1.2 ± 0.1 (Chapéu D´Uvas dam) to 104 ± 5 ng g-1 (Paraibuna river – Vila Ideal) dry weight, all within the limits established by CONAMA. The sediments of the municipality’s water resources are mainly composed of sand sediments and have a low total organic matter content (0.18 ± 0.01 % to 3.54 ± 0.05 %). Strong correlation was observed between the total concentration of the analytes and the contents of total organic matter and mud (silt + clay) present in the collected samples. In addition, loss of sensitivity of the method was observed with the increase of the TOC content in the samples. Despite the low total concentration found in the samples, the HPAs profile in the urban center of the city suggests that they were introduced into the environment by pyrolytic sources, resulting from the burning of biomass and fossil fuels, with a low probability of causing damage to aquatic systems studied.