Quaternary ammonium compounds (QACs) are a diverse group of organic chemicals with molecular masses ranging from 100 to 600 g/mol and alkyl side-chains of 2 to 20 C atoms. The majority of QACs are released into the environment through wastewater effluents due to their use in personal care products (fabric softeners, soaps, hair products) and as emerging solvents in the chemical industry. While hydrophobic QACs with long side-chains (10 to 20 C atoms) adsorb strongly to sewage sludge and sediments, short-chained (2 to 10 C atom) QACs are likely to remain in the water phase. The goal of this project was to develop and apply a liquid chromatography high-resolution mass spectrometry (LC-HRMS) method for a quantitative and qualitative analysis of QACs with alkyl side-chains of 2 to 18 C in water and sediment samples collected across the state of Minnesota. Optimal retention, good peak-shapes, and minimal carry-over was achieved for 22 QACs with nano-flow, hydrophilic interaction liquid chromatography (HILIC). A sample preparation procedure consisting of solid-phase extraction (SPE) with a mixed-mode sorbent material was developed for 250 ml water samples and resulted in absolute recoveries of 15-110% and quantification limits of 20-250 ng/L. Sediment samples (250 mg) were extracted in acidic methanol under sonication before SPE, leading to absolute recoveries of 10-80% and quantification limits of 40-200 ng/g. Overall, target analysis and suspect-screening was performed in 3 lake sediment cores with different levels of anthropogenic impact as well as a number of effluent grab samples collected from various wastewater treatment plants. These results will allow an initial assessment of current and past input levels of a broad range of QACs across the state of Minnesota.

Quantification and suspect-screening of a broad range of quaternary ammonium compounds in wastewater effluents and sediment cores from across Minnesota

2019 Spring National Meeting

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