Soft ionization by chemical reaction in transfer-high-resolution mass spectrometry for clinical exhaled breath profiling.

Exhaled breath analysis represents a rapid and non-invasive strategy for detecting volatile organic compounds (VOCs) that mirror human metabolic activity and pathological processes. The soft ionization by chemical reaction in transfer (SICRIT) interface, when integrated with high-resolution mass spectrometry (HRMS), provides a flexible and powerful alternative to conventional analytical techniques for breath analysis. This study evaluated feasibility, analytical reproducibility, and chemical coverage of SICRIT-HRMS for clinical exhaled breath analysis. Signal processing included feature alignment, filtering and compound annotation through the Human Metabolome Database (HMDB) and the Human Breathomics Database (HBDB). In 40 healthy volunteers, SICRIT-HRMS reproducibly detected 604 spectral features (80% matching HMDB, 56% HBDB), including alkanes (oxidative stress markers) and semi-volatile amino acids (likely from airway microdroplets). Median reproducibility across exhalations was 13%, and cosine similarity between VOC profiles reached 0.98 within individuals. Pathway enrichment analysis revealed a significant contribution of amino-acid and lipid metabolism. Twenty-five VOCs were associated with gender and six with fasting duration. SICRIT-HRMS enables high-resolution, real-time profiling of the human breath metabolome with strong reproducibility and broad chemical coverage beyond classical VOCs. Its unique capabilities position it as a comprehensive tool for breathomics research and future translational diagnostic applications. ClinicalTrials.gov Identifier: NCT06020521.