Improved pre-concentration and detection methods for volatile sulphur breath constituents

Area of Science:

• Analytical Chemistry
• Environmental Science
• Biochemistry

Background:

• Volatile sulfur compounds (VSCs) in breath are important biomarkers.
• Accurate determination of VSCs requires effective pre-concentration and detection methods.
• Challenges include compound stability, humidity, and oxygen interference.

Purpose of the Study:

• To evaluate solid phase microextraction (SPME) and sorbent trapping for VSC pre-concentration.
• To compare flame photometric detector (FPD) and mass selective detector (MSD) for VSC determination.
• To investigate factors affecting VSC analysis in breath gas.

Main Methods:

• Gas chromatography coupled with SPME and sorbent trapping.
• Detection using FPD and MSD.
• Analysis of H2S, MeSH, EtSH, DMS, COS, and CS2.
• Investigation of humidity, oxygen, and compound stability.
• Breath sample collection in Tedlar bags with humidity removal.

Main Results:

• SPME-MSD achieved parts-per-trillion (ppt) detection limits for VSCs (0.15-2.3 ppb).
• Sorbent trapping with Tenax TA/Carboxen 1000 and MSD yielded excellent LODs (0.03-0.3 ppb).
• VSC stability was poor in SPME vials and sorbent tubes (30-40% loss in 2h).
• FPD sensitivity was satisfactory only with sorbent trapping.

Conclusions:

• SPME-MSD is a fast, reliable method for VSC determination in breath, despite stability issues.
• Sorbent trapping offers superior LODs but suffers from poor VSC stability.
• Optimized sampling with humidity removal is crucial for accurate VSC analysis.