Authors: Taichi Yamazaki Akiko Takatsu
Publish Date: 2014/07/06
Volume: 19, Issue: 4, Pages: 275-282
Abstract
Purity evaluation of amino acids using nuclear magnetic resonance spectroscopy is reported Three amino acids aspartic acid valine and arginine and certified reference materials CRMs such as acidic neutral and basic amino acids as well as a low pure sample of valine were used as the analytes DCl solution D2O and NaOD solution were used as the preparation solvents The quantitative values were obtained from all observed signals and compared with the certified values of the CRMs When an amino acid was dissolved in water a strong HOD signal due to proton exchange was observed When the signal adjoining the HOD signal was considered in the evaluation the accurate quantitative value could not be obtained Therefore under optimized conditions the analyte signals separated from the HOD signal were chosen for purity determination of amino acids As a result the quantitative values were in agreement with the certified values of CRMs An expanded uncertainty was estimated to be approximately 0002 kg kg−1 We also discuss the effect of impurities on purity determination based on all signals and conclude that agreement of quantitative values determined from different signals in a molecule is a good indication of the accuracy of the results
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