Assessment of wastewater pollution by gas chromatography and high resolution Orbitrap mass spectrometry.

As a novelty, the combination of headspace solid phase microextraction and gas chromatography coupled to an Orbitrap mass analyzer in full scan mode (HS-SPME-GC-Orbitrap-MS) was evaluated for the monitoring of organic pollutants in wastewaters. The developed methodology showed good linearity (R2 > 0.999), sensitivity as well as suitable relative recoveries (89-115%) and precision values (RSD = 1-16%) for 15 polycyclic aromatic hydrocarbons (PAHs) selected as target compounds. Naphthalene, acenapthene and phenanthrene were found in the analyzed samples (influent and effluent wastewaters). Naphthalene was present in 62% of them, ranging from 1.33 to 24.32 ng L-1. Acenapthene was observed in 1 single sample (4.17 ng L-1) while phenanthrene was found in 7 samples (1.51-8.67 ng L-1). In addition, in order to identify other pollutants in the samples, retrospective analyses were addressed through target and non-target screenings. An in-house database containing close to 1,000 pollutants including, among others, polychlorinated biphenyls (PCBs), brominated diphenyl ethers (BDEs) and pesticides, was applied in the post-target analysis. For the non-target screening, after a deconvolution process, high resolution filtering (HRF) and Kovats retention index (KI) were used for tentative analyte identification. Thus, 51 additional pollutants were tentatively identified in the wastewaters, most of them used as flavoring agents and household product ingredients, highlighting the presence of linear alkyl benzenes (LABs).