Extração em microescala combinada com cromatografia a gás acoplada a espectrometria de massas para determinação simultânea de hidrocarbonetos policíclicos aromáticos e heterociclos sulfurados em sedimentos.

Abstract

This study describes a novel method based on an ultrasound-assisted extraction microscale device (UAE-MSD) for the rapid and simultaneous determination of polycyclic aromatic hydrocarbons (PAHs) and polycyclic aromatic sulfur heterocycles (PASHs) in marine sediments. Solvent extraction conditions were optimized by applying a simplex-centroid mixture design. Optimum conditions were used to validate and determine the concentrations of 17 PAHs and 7 PASHs. The best conditions were obtained by extracting sediments with 500 µmL of DCM:MeOH (65:35, v:v) over 23 minutes of sonication. Analytes were determined by gas chromatography/mass spectrometry in selective ion monitoring (GC-MS/SIM). Matrix effects were evaluated, and matrix-matched calibration was used for quantitation. Analytical method validation was carried out using the certified reference material NIST SRM 1941b, as well as sediment spiked with PASHs at three concentration levels. Recoveries ranged between 70.0 ± 3.5% and 119 ± 9.1% for PAH and 80.6 ± 10.4% and 120 ± 10% for PASHs. Linearity (R2) was ≥ 0.99 for all compounds. Method detection limits ranged from 8.8 to 30.2 ng g−1, while limits of quantification ranged from 29.4 to 1011 ng g−1. UAE-MSD was applied to marine sediments exposed to different anthropogenic impacts collected in Todos os Santos Bay, Brazil. PAH concentrations ranged from <LOQ to 667 ng g -1, while PASH levels were <LOQ to 1152 ng g-1. Dibenzothiophene was the compound presented in the highest concentration in all samples, with values up to 249 ng g-1. The results indicated contributions of pyrogenic sources from all compounds. The developed method can potentially be applied to extract trace levels of compounds in different solid matrices to minimize extraction time and solvent consumption.