Quantifying exhaled acetone and isoprene through solid phase microextraction and gas chromatography-mass spectrometry

Eray Schulz; Mark Woollam; Sneha Vashistha; Mangilal Agarwal

doi:10.1016/j.aca.2024.342468

Quantifying exhaled acetone and isoprene through solid phase microextraction and gas chromatography-mass spectrometry

Anal Chim Acta. 2024 May 1:1301:342468. doi: 10.1016/j.aca.2024.342468. Epub 2024 Mar 12.

Authors

Eray Schulz¹, Mark Woollam¹, Sneha Vashistha², Mangilal Agarwal³

Affiliations

¹ Integrated Nanosystems Development Institute, Indiana University-Purdue University, Indianapolis, IN, 46202, USA; Department of Chemistry and Chemical Biology, Indiana University-Purdue University, Indianapolis, IN, 46202, USA.
² Integrated Nanosystems Development Institute, Indiana University-Purdue University, Indianapolis, IN, 46202, USA.
³ Integrated Nanosystems Development Institute, Indiana University-Purdue University, Indianapolis, IN, 46202, USA; Department of Chemistry and Chemical Biology, Indiana University-Purdue University, Indianapolis, IN, 46202, USA; Department of BioHealth Informatics, Indiana University-Purdue University, Indianapolis, IN, 46202, USA. Electronic address: agarwal@iupui.edu.

PMID: 38553125
DOI: 10.1016/j.aca.2024.342468

Abstract

Background: Acetone, isoprene, and other volatile organic compounds (VOCs) in exhaled breath have been shown to be biomarkers for many medical conditions. Researchers use different techniques for VOC detection, including solid phase microextraction (SPME), to preconcentrate volatile analytes prior to instrumental analysis by gas chromatography-mass spectrometry (GC-MS). These techniques include a previously developed method to detect VOCs in breath directly using SPME, but it is uncommon for studies to quantify exhaled volatiles because it can be time consuming due to the need of many external/internal standards, and there is no standardized or widely accepted method. The objective of this study was to develop an accessible method to quantify acetone and isoprene in breath by SPME GC-MS.

Results: A system was developed to mimic human exhalation and expose VOCs to a SPME fiber in the gas phase at known concentrations. VOCs were bubbled/diluted with dry air at a fixed flow rate, duration, and volume that was comparable to a previously developed breath sampling method. Identification of acetone and isoprene through GC-MS was verified using standards and observing overlaps in chromatographic retention/mass spectral fragmentation. Calibration curves were developed for these two analytes, which showed a high degree of linear correlation. Acetone and isoprene displayed limits of detection/quantification equal to 12 ppb/37 ppb and 73 ppb/222 ppb respectively. Quantification results in healthy breath samples (n = 15) showed acetone concentrations spanned between 71 ppb and 294 ppb, and isoprene varied between 170 ppb and 990 ppb. Both concentration ranges for acetone and isoprene in this study overlap with those reported in existing literature.

Significance: Results indicate the development of a system to quantify acetone and isoprene in breath that can be adapted to diverse sampling methods and instrumental analyses beyond SPME GC-MS.

Keywords: Exhaled breath; Gas chromatography; Mass spectrometry; Quantification; Solid phase microextraction; Volatile organic compound.

MeSH terms

Acetone / analysis
Breath Tests / methods
Butadienes*
Exhalation
Gas Chromatography-Mass Spectrometry / methods
Hemiterpenes*
Humans
Solid Phase Microextraction* / methods
Volatile Organic Compounds* / analysis

Substances

Acetone
isoprene
Volatile Organic Compounds
Butadienes
Hemiterpenes