Optimized procedure for the determination of alkylamines in airborne particulate matter of anthropized areas

Due to their role in the formation of secondary aerosol, the concentrations of the most abundant aliphatic amines (methylamine (MA), dimethylamine (DMA), ethylamine (EA), diethylamine (DEA), propylamine (PA), and butylamine (BA)) present in the aerosol of a very anthropized area were measured by an optimized analytical procedure. PMinline-formula₁₀ samples were collected in the tanning district of Vicenza (in the Po Valley, northern Italy) in autumn 2020. Alkylamines were extracted in water and converted to carbamates through derivatization with Fmoc-OSu (9-fluorenylmethoxycarbonyl-N-hydroxysuccinimide) for subsequent determination by ultra-high-performance liquid chromatography (UHPLC) with fluorescence detection. The procedure has been optimized, obtaining very satisfactory analytical performances: limits of detection (LODs) were in the range of 0.09–0.26 ng minline-formula⁻³, with an average uncertainty of 3.4 % and recoveries of 95 %–101 %. The mean total concentration of the six amines measured in this study was inline-formula37±17 ng minline-formula⁻³, with DMA making the largest contribution. The proposed procedure may contribute to a better characterization of the local aerosol. In our preliminary investigation, Pearson's correlation test showed that amines correlate strongly with each other and with secondary inorganic ions (NHinline-formula $M5inlinescrollmathml{}_{\mathrm{normal\; 4}}^{+}$ 8pt15ptsvg-formulamathimgaa378b71f34a6c23384fc0eb7c6e7621 ar-1-29-2023-ie00001.svg8pt15ptar-1-29-2023-ie00001.png , NOinline-formula $M6inlinescrollmathml{}_{\mathrm{normal\; 3}}^{-}$ 9pt16ptsvg-formulamathimga6a4c5911a740e8377438efb607d4b86 ar-1-29-2023-ie00002.svg9pt16ptar-1-29-2023-ie00002.png , and SOinline-formula $M7inlinescrollmathml{}_{\mathrm{normal\; 4}}^{\mathrm{normal\; 2}-}$ 13pt17ptsvg-formulamathimg972fd8e8ae3fad8e22756ca8f92061a6 ar-1-29-2023-ie00003.svg13pt17ptar-1-29-2023-ie00003.png ), confirming that they compete with ammonia in the acid–base atmospheric processes that lead to the formation of nitrate and sulfate particles. The developed method allows us to gather critical information about the load of aliphatic amines in particulate matter (PM) to gain more insights into the sources and fate of these chemicals in the atmosphere.