Mill, T., White, J., Leib, R., & Serikov, V. (2014, 10-14 August). Toward a breathable biomarker for physiological stress. Paper presented at the ACS National Meeting & Exposition, San Francisco, CA.
A variety of dangerous and stressful situations confront military personnel, firefighters, and rescue workers on a daily basis. The effectiveness of these individuals under highly stressful conditions can be seriously compromised which is why a reliable method for assessing stress levels in real time would be a highly valuable tool for minimizing physiological stress. If a volatile biomarker, uniquely identified with high stress levels, formed in epithelial lung fluid (ELF), it might be detected by breath collection and analysis, thus avoiding the need for sampling blood or urine.
We have developed preliminary laboratory data for formation of volatile aldehydes produced by oxidatation of amino acids found in ELF exposed to HOCl. Formation of HOCl, via oxidation of chloride ion, is associated with physiological stress and uniquely converts amino acids to aldehydes via the intermediate imine.
Valine is found in plasma and ELF. Treatment of ∼0.3 mM Val in plasma or ∼0.05 mM Val in ELF with 0.3 or 1 mM HOCl followed by air -volatilization of products from the reaction mixtures gave ∼12 or150 ppm i-butyraldehyde in collected air. Isopentanals, from oxidized Leu and i-Leu present in plasma were also detected using high-resolution time-of-flight mass spectrometry with 118 nm VUV photon ionization. This technique generates strong parent ion-signals for the aldehydes, thus providing sub–ppb detection limits without need for prior GC separation.