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A certified urea reference material (NMIJ CRM 6006-a) as a reliable calibrant for the elemental analyses of amino acids and food samples.

Authors
  • Itoh, Nobuyasu
  • Yamazaki, Taichi
  • Sato, Ayako
  • Numata, Masahiko
  • Takatsu, Akiko
Type
Published Article
Journal
Analytical sciences : the international journal of the Japan Society for Analytical Chemistry
Publication Date
Jan 01, 2014
Volume
30
Issue
4
Pages
471–476
Identifiers
PMID: 24717656
Source
Medline
License
Unknown

Abstract

We examined the reliability of a certified reference material (CRM) for urea (NMIJ CRM 6006-a) as a calibrant for N, C, and H in elemental analyzers. Only the N content for this CRM is provided as an indicative value. To estimate the C and H contents of the urea CRM, we took into account the purity of the urea and the presence of other identified impurities. When we examined the use of various masses of the calibrant (0.2 to 2 mg), we unexpectedly observed low signal intensities for small masses of H and N, but these plateaued at about 2 mg. We therefore analyzed four amino acid CRMs and four food CRMs on a 2-mg scale with the urea CRM as the calibrant. For the amino acid CRMs, the differences in the analytical and theoretical contents (≤0.0026 kg/kg) were acceptable with good repeatability (≤0.0013 kg/kg in standard deviation; n = 4). For food CRMs, comparable repeatabilities to those obtained with amino acid CRMs (≤0.0025 kg/kg in standard deviation; n = 4) were obtained. The urea CRM can therefore be used as a reliable calibrant for C, H, and N in an elemental analyzer.

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