Quantification of volatile organic compounds by secondary electrospray ionization-high resolution mass spectrometry

Chao Liu; Jiafa Zeng; Pablo Sinues; Mingliang Fang; Zhen Zhou; Xue Li

doi:10.1016/j.aca.2021.338876

Quantification of volatile organic compounds by secondary electrospray ionization-high resolution mass spectrometry

Anal Chim Acta. 2021 Oct 2:1180:338876. doi: 10.1016/j.aca.2021.338876. Epub 2021 Jul 26.

Authors

Chao Liu¹, Jiafa Zeng², Pablo Sinues³, Mingliang Fang⁴, Zhen Zhou⁵, Xue Li⁶

Affiliations

¹ Institute of Mass Spectrometry and Atmospheric Environment, Jinan University, Guangzhou, 510632, China.
² Institute of Mass Spectrometry and Atmospheric Environment, Jinan University, Guangzhou, 510632, China; Department of Biomedical Engineering, Basel University, Allschwil, 4123, Switzerland; University of Basel Children's Hospital (UKBB), Basel, 4056, Switzerland.
³ Department of Biomedical Engineering, Basel University, Allschwil, 4123, Switzerland; University of Basel Children's Hospital (UKBB), Basel, 4056, Switzerland.
⁴ School of Civil and Environmental Engineering, Nanyang Technological University, Singapore, 639798, Singapore.
⁵ Institute of Mass Spectrometry and Atmospheric Environment, Jinan University, Guangzhou, 510632, China; Guangzhou Hexin Instrument Co., LTD., Guangzhou, 510530, China; Guangdong-Hongkong-Macau Joint Laboratory of Collaborative Innovation for Environmental Quality, Guangzhou, 510632, China.
⁶ Institute of Mass Spectrometry and Atmospheric Environment, Jinan University, Guangzhou, 510632, China; Guangzhou Hexin Instrument Co., LTD., Guangzhou, 510530, China; Guangdong-Hongkong-Macau Joint Laboratory of Collaborative Innovation for Environmental Quality, Guangzhou, 510632, China. Electronic address: tamylee@jnu.edu.cn.

PMID: 34538336
DOI: 10.1016/j.aca.2021.338876

Abstract

Secondary electrospray ionization coupled with high resolution mass spectrometry (SESI-HRMS) is a direct mass spectrometry technique, which can identify trace volatile organic compounds (VOCs) in real time without sample pretreatment and chromatographic separation. SESI-HRMS has been successfully applied in multiple applications, including breath analysis, animals and plants VOCs emissions, analysis of headspace of cell cultures and indoor and outdoor air. The range of areas where the technique can potentially have a substantial impact is very broad. However, one critical aspect that requires further development to consolidate the technique is absolute quantification. Therefore, in this study we aim to develop a quantitative method for eight representative VOCs, including ketones (acetone, 2-butanone and 2-pentanone), alkenes (isoprene and α-terpinene) and aromatics (toluene, styrene and mesitylene). The mass spectrometric platform includes a commercial SESI source hyphenated with a Q-Exactive hybrid quadrupole Orbitrap high resolution mass spectrometer. Within the concentration range of 0-100 ppbv studied, the optimal coefficient of determination for linear regression (R² = 0.993-0.999) between signal intensity and concentration is obtained in the range of 0-10 ppbv for all eight VOCs. The detection limits range between 3 (2-Pentanone) and 15 (Acetone) pptv. The intra-day (n = 10) and inter-day (n = 30) coefficients of variation (CV) are ≤ 6% and ≤10%, respectively. Finally the method is applied for the fast evaluation (<5 min) of different materials widely used for the collection, storage or pretreatment of gas sample. Better recovery of trace levels of eight VOCs is observed for PTFE gas sampling bag as compared to Nalophan and Tedlar bags; when Nafion tube is used to pretreat the gas sample, recovery of ≤50% are obtained for 2-pentanone, α-terpinene and all three aromatics.

Keywords: High resolution mass spectrometry; Quantitative analysis; Secondary electrospray ionization; Volatile organic compounds.

MeSH terms

Acetone
Breath Tests
Spectrometry, Mass, Electrospray Ionization
Volatile Organic Compounds*

Substances

Volatile Organic Compounds
Acetone