Quaternary ammonium compounds (QACs) are a class of antimicrobial disinfectants whose use in cleaning products exponentially increased with the COVID-19 pandemic. Chemically, their low vapor pressure indicates a proclivity to persist on surfaces. However, there are no standardized analytical methods for QAC surface sampling and analysis even though their persistence poses a possible environmental risk. There are no published studies analyzing their occurrence on mass transportation vehicles-a high occupancy, close contact microenvironment that could facilitate the spread the COVID-19 virus. Here, we introduce a more robust liquid chromatography mass spectrometry (LC-MS) method for the analysis of QACs, describe the development of a simple surface sampling and extraction protocol, and verify the applicability through the analysis of surface samples collected from in-service public transportation buses.<br/>A rapid, sensitive LC-MS method was developed for the analysis of 8 target QACs using a Q-Exactive HF Hybrid Quadrupole-Orbitrap MS equipped with an electrospray ionization (ESI) source and Dionex UltiMate 3000 UHPLC system. Chromatographic separation of all analytes was achieved in under 10 minutes. QAC standard mixtures at concentrations between 2 µg/mL and 0.01 ng/mL were analyzed to validate this new method. All correlation coefficients were reported at r &gt; 0.986, and LODs ranged from 0.007-2.103 ng/mL, confirming the method’s sensitivity. A previously reported surface sampling and extraction protocol was modified to further simplify the procedure and expand the number of target compounds. A sampling protocol was optimized from 10 commercially available wipes and 4 solvent types by quantifying recovery from the surface. Band-Aid small gauze pads spiked with isopropanol had the highest recovery efficiencies, ranging from 61.5-102.9% across all analytes. To test the real-world applicability, wipe samples were collected from 4 in-circulation New Jersey Transit buses over the course of 30 days to assess the occurrence and longevity of QACs on sanitized mass transportation vehicles. Concentrations of QACs were detected on every wipe sample taken from all buses at all sampled time points, confirming their tendency to remain on hard surfaces.

Surface sampling and liquid chromatography mass spectrometry method for the analysis of quaternary ammonium compounds collected from public transportation vehicles in NJ

ACS Spring 2022

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