Aromatic organosulfates in atmospheric aerosols: Synthesis, characterization, and abundance

Abstract

Aromatic organosulfates are identified and quantified in fine particulate matter (PM2.5) from Lahore, Pakistan, Godavari, Nepal, and Pasadena, California. To support detection and quantification, authentic standards of phenyl sulfate, benzyl sulfate, 3-and 4-methylphenyl sulfate and 2-, 3-, and 4-methylbenzyl sulfate were synthesized. Authentic standards and aerosol samples were analyzed by ultra-performance liquid chromatography (UPLC) coupled to negative electrospray ionization (ESI) quadrupole time-of-flight (ToF) mass spectrometry. Benzyl sulfate was present in all three locations at concentrations ranging from 4 – 90 pg m−3. Phenyl sulfate, methylphenyl sulfates and methylbenzyl sulfates were observed intermittently with abundances of 4 pg m−3, 2-31 pg m−3, 109 pg m−3, respectively. Characteristic fragment ions of aromatic organosulfates include the sulfite radical (•SO3−, m/z 80) and the sulfate radical (•SO4−,m/z 96). Instrumental response factors of phenyl and benzyl sulfates varied by a factor of 4.3, indicating that structurally-similar organosulfates may have significantly different instrumental responses and highlighting the need to develop authentic standards for absolute quantitation organosulfates. In an effort to better understand the sources of aromatic organosulfates to the atmosphere, chamber experiments with the precursor toluene were conducted under conditions that form biogenic organosulfates. Aromatic organosulfates were not detected in the chamber samples, suggesting that they form through different pathways, have different precursors (e.g. naphthalene or methylnaphthalene), or are emitted from primary sources.

The Molecular Identification of Organic Compounds in the Atmosphere: State of the Art and Challenges

“…However many challenges limit the application of LC/ESI-MS techniques, such as the lack of authentic standards for aromatic-derived organosulfates. 346 Future work should focus on synthesizing these compounds. Mass accuracy, on the other hand, strongly depends on various parameters including scan rate, signal-to-noise ratio, and resolving power of the instrument.…”

Organosulfates in atmospheric aerosol: synthesis and quantitative analysis of PM<sub>2.5</sub> from Xi'an, northwestern China

“…However, quantification of organosulfates is a challenging task due to the lack of authentic standards and incomplete understanding of the sources, precursors and formation processes of organosulfates. To date, many studies of organosulfates have remained at the qualitative level, although a limited number of studies have provided quantitative or semi-quantitative analysis of certain organosulfates (e.g., Kundu et al, 2013;Staudt et al, 2014;Ma et al, 2014;Olson et al, 2011;Hettiyadura et al, 2017). Moreover, several studies show that organosulfates are present as a wide range of species with individual species such as the organosulfate derived from isoprene epoxydiols (IEPOXs) contributing 0.2-1.4 % of the total organic aerosol mass (Liao et al, 2015).…”

“…Kundu et al (2013) quantified benzyl sulfate (C 7 H 7 SO − 4 ) and identified its homologous series with increasing number of methylene groups (C 8 H 9 SO − 4 and C 9 H 11 SO − 4 ) in Lahore, Pakistan. Furthermore, Staudt et al (2014) synthesized phenyl sulfate, benzyl sulfate, 3-and 4-methylphenyl sulfate and 2-, 3-, and 4-methylbenzyl sulfate and quantified them in aerosols collected in urban samples from Lahore and Pasadena, USA as well as Nepal. Ma et al (2014) reported the contribution up to 64 % from aromatic organosulfates to the sum of identified organosulfates during winter in Shanghai, while Wang et al (2016) found aromatic organosulfates to constitute less than 22 % of the detected number of organosulfates in Shanghai, Nanjing and Wuhan.…”

“…General scheme for the synthesis of organosulfate, modified from Staudt et al (2014) and Hettiyadura et al (2015).…”

Photooxidation of cyclohexene in the presence of SO<sub>2</sub>: SOA yield and chemical composition

“…Qualitative analyses of organosulfates in SOA have been gaining more attention and development in recent years (Lin et al, 2012;Shalamzari et al, 2013;Staudt et al, 2014). Riva et al (2015) investigated the formation of organosulfates from photooxidation of polycyclic aromatic hydrocarbons and found that, in the presence of sulfate aerosol, this photooxidation was a hitherto unrecognized source of anthropogenic secondary organosulfur compounds (Riva et al, 2015).…”