Comprehensive utilization of NMR spectra–evaluation of NMR-based quantification of amino acids for research and patient care

Objectives In 1 H nuclear magnetic resonance spectroscopy (NMR), a single measurement can yield insights into hundreds of metabolites. The use of NMR is expanding in research, with comprehensive datasets readily available. To fully leverage the spectral data, e.g. for amino acid (AA) detection, evaluating the quality of NMR quantification is crucial. For this, we compared the results for 15 AAs obtained from 1 H NMR and a clinical HPLC platform. Methods 1 H NMR and HPLC measurements of 15 AAs from 90 samples are compared by Spearman correlation coefficients and Passing-Bablok analysis. Imprecision is evaluated by coefficients of variation based on duplicates. Results 1 H NMR measurements of two AAs show high correlation and good agreement to HPLC measured levels (phenylalanine, alanine). Three more AA measurements reveal high correlation but systematic bias (tyrosine, valine, glycine). NMR results of six investigated AAs are less comparable (ornithine, threonine, histidine, isoleucine, leucine, lysine). Four measurands could not be evaluated (glutamine, glutamic acid, asparagine, methionine). Conclusions Analytical quality varies considerably among the investigated AAs. A limited number of AAs show good concordance with results from HPLC supporting selective use of NMR spectra for AA analysis. While NMR holds promise in both research and clinical settings, it is currently not suitable for comprehensive AA monitoring for diagnostic purpose.