Determination of 25 quaternary ammonium compounds in sludge by liquid chromatography–mass spectrometry

Abstract

With the pandemic of COVID-19, the application of quaternary ammonium compounds (QACs), which can be used in SARS-CoV-2 disinfection products, has increased substantially. QACs cumulated in sewer system are ultimately deposited and enriched in sludge. QACs in the environment can adversely affect human health and the environment. In this study, a liquid chromatography–mass spectrometry method was established for the simultaneous determination of 25 QACs in sludge samples. Ultrasonic extraction and filtration of the samples was performed using a 50 mM hydrochloric acid–methanol solution. The samples were separated by liquid chromatography and detected in multiple reaction monitoring mode. The matrix effects of the sludge on the 25 QACs ranged from − 25.5% to 7.2%. All substances showed good linearity in the range of 0.5–100 ng/mL, with all determination coefficients ( R 2 ) greater than 0.999. The method detection limits (MDLs) were 9.0 ng/g for alkyltrimethylammonium chloride (ATMAC), 3.0 ng/g for benzylalkyldimethylammonium chloride (BAC), and 3.0 ng/g for dialkyldimethylammonium chloride (DADMAC). The spiked recovery rates were in the range of 74–107%, while the relative standard deviations were in the range of 0.8–20.6%. Considering its sensitivity, accuracy, and easy operation, the proposed method in this study was used to determine 22 sludge samples collected from a comprehensive wastewater treatment plant. The results showed that the concentrations of ΣATMACs, ΣBACs, and ΣDADMACs were 19.684, 3.199, and 8.344 μg/g, respectively. The main components included ATMAC-C16, ATMAC-C18, ATMAC-C20, ATMAC-C22, BAC-C12, and DADMAC-C18:C18, with concentrations exceeding 1.0 μg/g. The concentration relationships of different components in the congeners showed that some components were of similar origin.

High-Resolution Mass Spectrometry Screening of Quaternary Ammonium Compounds (QACs) in Dust from Homes and Various Microenvironments in South China

“…Among the newly identified QACs, 16 were confirmed with commercially available standards (level S1), 11 matched reference MS/MS fragment ions (level S2), and 1 was tentatively identified through characteristic MS/MS fragmentations (level S3). Of these emerging QACs identified, only 13 have been reported in the environments, 9,13,23,24,30,42,48,49 demonstrating the effectiveness of the QAC screening strategy applied in the present study. The newly identified QACs were divided into three groups based on their structural similarity to traditional QACs, including 9 BAC analogues, 10 DADMAC analogues, and 9 ATMAC analogues (Figures 1 and S3−S5).…”