Deciphering ¹³C and ³⁴S Isotopes of Organosulfates in Urban Aerosols by FT-ICR Mass Spectrometry

Abstract

Organosulfates (OSs) are some of the important components of secondary organic aerosols in ambient air. However, little is known about the stable carbon and sulfur isotopic compositions of OSs. Here, we identified the isotopic pair 12 C n / 13 C 12 C n−1 and 32 S n / 34 S 32 S n−1 formulas in urban aerosols using ultra-highresolution Fourier transform ion cyclotron resonance mass spectrometry. Family series of 694−1649 13 C 32 S OSs and 40−144 12 C 34 S OSs with completely coherent carbon chains were detected, accounting for 37−52% and 2.2−4.5%, respectively, of the observed 12 C 32 S OSs. OSs with detected isotopic peaks have relatively high levels of saturation and high volatilities, especially those containing 34 S isotopes with H/C > 1.5. Moreover, the δ 13 C and δ 34 S values of OSs were estimated with mean values ranging from −22‰ to −0.87‰ and from −1‰ to 26‰, respectively. Notably, unsaturated OSs might be more enriched with 34 S than aliphatic ones. Furthermore, all detected 12 C 34 S OSs are in the low-O/C corridor with a low carbon oxidation state, which are mostly volatile and low-volatile organic compounds with high volatility, implying that they are generated by gasphase oxidation. These findings represent a first step toward identifying the individual molecules of 13 C and 34 S isotopic OSs in atmospheric aerosols.

Elucidating Dissolved Organic Sulfur in the Coastal Environment by Improved Online Liquid Chromatography Coupled to FT‐ICR Mass Spectrometry

“…And the eluate was immediately concentrated to 1 mL by a rotary evaporator. Detailed steps were described in the supplementary information and previous organic sulfur associated studies (Su et al., 2022; Xie et al., 2022). Blank samples of different media were calibrated as blanks for the laboratory experiments with the same procedure of filtration and enrichment from the initial collection to the pre‐treatment.…”

Procedures from samples to sulfur isotopic data: A review

“…262,263 A method to measure 32 S n / 34 S 32 S nÀ1 in organosulfates using fourier transform-ion cyclotron resonance-mass spectrometry (FT-ICR-MS) has been developed. 264 Aerosol samples are extracted three times with ultrasonic MQ before being eluted with methanol. Finally, samples are concentrated using a rotary evaporator and redissolved in 1 mL of methanol for analysis.…”

“…A method to measure 32 S n / 34 S 32 S n −1 in organosulfates using fourier transform‐ion cyclotron resonance‐mass spectrometry (FT‐ICR‐MS) has been developed 264 . Aerosol samples are extracted three times with ultrasonic MQ before being eluted with methanol.…”

Peatland Wildfires Enhance Nitrogen-Containing Organic Compounds in Marine Aerosols over the Western Pacific

“…To address this issue, we employ FT-ICR MS, a cutting-edge analytical technique renowned for its ultrahigh resolution, superior mass accuracy, and sensitivity. This powerful instrument has been applied to various environmental samples, including atmospheric aerosols, 14,19,33 fog/cloud/rain-water, 34−36 river water, 37−39 soil, 40−42 and marine water and sediments. 43−45 While electrospray ionization (ESI) positive mode is commonly used, it is particularly well suited for detecting basic or neutral nitrogen compounds such as cysteine and glutathione.…”