Abstract
Amino acids studies are a cornerstone in clinical medicine. However, current analysis methods are time-consuming, invasive, and suffer from pre-analytic pitfalls. We hypothesized that blood levels of amino acids can be accurately estimated in real-time via breath analysis, and thus may facilitate more efficient diagnostics and give insights into the human physiology.
The amino acid profile in 37 subjects was synchronously determined by high performance liquid chromatography (blood plasma) and the hitherto unexplored technique, for amino acids quantification in breath, of secondary electrospray ionization coupled to high-resolution mass spectrometry. Subjects were split into training and test sets to validate accuracy. Longitudinal measurements in three subjects over 12 hours were additionally obtained.
Levels of 8 slightly volatile amino acids (alanine, valine, [iso]leucine, glycine, proline, lysine, phenylalanine, ornithine) could be quantified in the exhalome with a coefficient of variation of less than 13%. Exhalome validation studies yielded unique accuracy levels for each amino acids, averaging at -4±5% when compared to blood levels. High variation occurred particularly in amino acids with a low plasma concentration.
We have demonstrated for the first time that amino acids can be quantified in real-time in the human exhalome and their concentrations correspond to their blood levels. Though this novel non-invasive technique needs further investigation, exhalome analysis may provide significant improvements when compared to traditional analytical offline methods, e.g., real-time determination of plasma free amino acids profiles.
- Copyright ©the authors 2016
