Silica decorated with palladium nanoparticles applied in a miniaturized method to separation and quantification of sulfur-containing compounds in fuel samples

This paper presents the synthesis of novel silica decorated with palladium nanoparticles (PdNP) and its application as a stationary phase in a miniaturized fractionation procedure to quantify polycyclic aromatic sulfur heterocycles (PASHs) in fuel samples. The PdNP phase was characterized by morphological and textural analyses and a high surface area (450 m² g⁻¹) and very small palladium nanoparticles (4.1 nm of diameter) were obtained. The influence of experimental variables such as solvent used in the elution and the amount of stationary phase and sample has been considered in the optimization process to obtain a miniaturized fractionation. The PASHs were analyzed by gas chromatography coupled to a triple quadruple mass spectrometer (GC–MS/MS). Under optimum conditions, the procedure was validated in terms of linearity, accuracy and precision. The limit of detection ranged from 0.012 mg L⁻¹ (benzothiophene) to 0.058 mg L⁻¹ (benzonaphthothiophene). Correlation coefficients (R²) ≥ 0.99 were obtained for all compounds. The mean recovery for most of PASHs ranged from 66.2 ± 5 % to 119 ± 3 %, with interday and intraday precision <20 %. The proposed procedure was applied to determine PASHs in four fuel samples from different origins and total sulfur. The concentrations ranged from 0.406 ug g⁻¹ to 4362 µg g⁻¹. PASH compounds were mainly DBT and BNT classes. The obtained results open the possibility of further applications of the PdNP phase in environmentally friendly procedures for the perspectives of fuels and biofuels with increasingly lower concentrations of PASH.