Gas chromatography - atmospheric pressure chemical ionization - high-resolution mass spectrometry to evaluate pressurized liquid extraction of targeted and non-targeted contaminants from sediments

Abstract

Contamination of aquatic environments by chemical substances poses a growing concern. Among the different environmental compartments, sediments act as sink for many medium to low polarity contaminants. To determine such substances, we have evaluated the potential of gas chromatography coupled to atmospheric pressure chemical ionization - high-resolution mass spectrometry (GC-APCI-HRMS) for targeted and non-targeted screening of organic pollutants in different sediment matrices. First, 6 different pressurized liquid extraction (PLE) conditions and up to 141 targeted compounds were evaluated in 3 types of sediment matrices. A combined one-step extraction with dichloromethane (DCM) and clean-up with silica yielded the highest recoveries (> 80 % for 96 contaminants), and was later applied to the analysis of sewage-impacted surface sediments from Guadalete Estuary (SW Spain), where up to 60 contaminants were measured at total concentrations from 115.3 to 862.5 ng g−1 dw. Polycyclic aromatic hydrocarbons (PAHs) were the most prevalent contaminants (59 %), followed by personal care products (PCPs) (25 %), industrial chemicals (11 %), and pesticides (4 %). Identification of unknown substances was conducted using mass spectral libraries, lists of suspect compounds, and in-silico fragmentation. From the over 8000 HRMS features measured in sediments, identification of 144 compounds was achieved, including different pharmaceuticals (iprodinazole, 8-methyl octahydrocoumarin), flame retardants (4-vinylcyclohexene, triphenylphosphine oxide), personal care products (5-Methyl-2-phenyl-2-hexenal), hydrocarbons (α-dodecene oxide), and pesticides (kinoprene). The application of the PLE followed by GC-APCI-HRMS methodology developed here in combination with existing liquid chromatography - HRMS (LC-HRMS) based methods will allow for a better characterization of current and upcoming chemical threats released into the environment.