Quantification of known and unknown terpenoid organosulfates in PM10 using untargeted LC–HRMS/MS: contrasting summertime rural Germany and the North China Plain

Abstract

Environmental context. Secondary organic aerosols account for a major fraction of atmospheric particulate matter, affecting both climate and human health. Organosulfates, abundant compounds in organic aerosols, are difficult to measure because of the lack of authentic standards. Here we quantify terpene-derived organosulfates in atmospheric particulate matter at a rural site in Germany and at the North China Plain using a combined target/non-target high-resolution mass spectrometry approach.Abstract. Organosulfates (OSs) are a ubiquitous class of compounds in atmospheric aerosol particles. However, a detailed quantification of OSs is commonly hampered because of missing authentic standards and the abundance of unknown OSs. Using a combined targeted and untargeted approach of high-resolution liquid chromatography-Orbitrap mass spectrometry (LC-Orbitrap MS), we quantified for the first time the total concentrations of known and unknown monoterpene (MT) and sesquiterpene (SQT) OSs in summertime PM 10 particulate matter from field studies in rural Germany (MEL) and the North China Plain (NCP). At each site, we observed more than 50 MT-OSs, 13 of which were detectable at both sites. For both locations, median concentrations of MT-OSs were in the range of 10 to 40 ng m À3 , to which the 13 common MT-OSs contributed on average .50 %. The main contributor to MT-OSs was C 9 H 16 O 7 S (MT-OS 267) with average mass concentrations of 2.23 and 6.38 ng m À3 for MEL and NCP respectively. The concentrations of MT-OSs correlated with the concentrations of MT oxidation products only for MEL. For NCP, the low concentrations of MT oxidation products (i.e. typically ,1 ng m À3 ) suggested a suppression of carboxylic acid formation under high concentrations of NO x and particulate sulfate. Furthermore, we observed 17 SQT-OSs for the MEL samples, whereas 40 SQT-OSs were detected in the NCP samples. Only five of these SQT-OSs were detectable at both sites. Correspondingly, the total concentrations of SQT-OSs were larger for NCP than for MEL, which suggested large differences in the particle chemistry. In particular, aerosol acidity was found to be a key factor during SQT-OS formation, and was probably not sufficient in the PM 10 from MEL.

Urban organic aerosol composition in Eastern China differs from North to South: Molecular insight from a liquid chromatography-Orbitrap mass spectrometry study

“…A major fraction organic species detected in ESI− are attributed to CHO− and CHON−, accounting for 30−42% and 39−55% in terms of peak abundance, respectively, and comprising 39-45% and 23-33% in terms of peak numbers, respectively. This is consistent with previous studies on Chinese urban OA by Wang et al (2017 and and Brüggemann et al (2019). Comparing the organic compounds detected in ESI− for the three cities, 139 formulas were observed in all cities as common formulas ( Fig.…”

“…Our recent Orbitrap MS study (Wang et al, 2018) showed that wintertime OA in PM2.5 collected in Beijing, China and Mainz, Germany were very different in terms of chemical composition. In contrast, for summertime OA from Germany and China, Brüggemann et al (2019) found similar compounds and concentrations of terpenoid organosulfates in PM10, demonstrating that biogenic emission can significantly affect OA composition at both locations. Ning et al (2019) analyzed the OA collected https://doi.org/10.5194/acp-2019-908 Preprint.…”

“…However, more CHOS− compounds with C > 10 and with DBEs lower than 1 are observed in Changchun−, such as C14H28O5S1, C13H26O5S1, C12H24O5S1, C11H22O5S1 and C11H20O6S1. These high-carbon-number-containing CHOS− compounds are likely formed from long-alkyl-chain compounds with less oxygenated functional groups, which were previously suggested to be emitted from traffic (Tao et al, 2014) or derived from sesquiterpene emissions (Brüggemann et al, 2019). However, as sesquiterpene emissions can be expected to be very low in wintertime at Changchun, the presence of these compounds further underlines the strong impact of anthropogenic emissions on CHOS− formation in Changchun−.…”

“…Recently, ultrahigh resolution mass spectrometry (UHRMS), such as Fourier transform ion cyclotron resonance mass spectrometry (FTICR−MS) and Orbitrap−MS, coupled with soft ionization sources (e.g., electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI)) have been introduced to elucidate the molecular composition of OA (Nizkorodov et al, 2011;Lin et al, 2012a;Lin et al, 2012b;Rincón et al, 2012;Noziere et al, 2015;Kourtchev et al, 2016;Tong et al, 2016;Tu et al, 2016;Brüggemann et al, 2017;Wang et al, 2017;Fleming et al, 2018;Laskin et al, 2018;Song et al, 2018;Wang et al, 2018;Brüggemann et al, 2019;Daellenbach et al, 2019;Ning et al, 2019;Wang et al, 2019a). Due to the two outstanding features of high resolving power and high mass accuracy, UHRMS can give precise elemental compositions of individual organic compounds.…”

Identification of Unknown Substances in Ambient Air (PM10), Profiles and Differences between Rural, Urban and Industrial Areas

“…In the literature, there are few studies related to non-target analysis in ambient air using liquid chromatographic techniques coupled to high-resolution mass spectrometry [ 34 , 35 , 36 , 37 , 38 ], but in some cases, only MS 2 fragmentation data were employed. The other published studies in the literature employed gas chromatography [ 39 , 40 , 41 ].…”