Our next step was to ship a new set of both pooled (n = 10) and single-donor (n = 17) samples from the DDL to NMIJ along with the DDL IS that had been developed by Stein et al.
Development of SI-traceable C-peptide certified reference material NMIJ CRM 6901-a using isotope-dilution mass spectrometry-based amino acid analyses.
 Nonstandard abbreviations: DDL, Diabetes Diagnostic Laboratory; NMIJ, National Metrology Institute of Japan; IS, internal standard.
 Bio-Medical Standards Group National Metrology Institute of Japan (NMIJ), National Institute of Advanced Industrial Science and Technology (AIST), Ibaraki, Japan
The relationship between NMIJ and DDL when both laboratories used the same internal standard (IS).
One of these values was based on less accurate absolute lattice spacing values from PTB, INRIM, and NMIJ
An extensive standardization project for clinical chemistry in Japan was initiated by the Japanese Committee for Clinical Laboratory Standards and the NMIJ with the support of the New Energy and Industrial Technology Development Organization in 2005-2007.
The NMIJ initiated an effort to develop CRMs for proteins and peptides at the same time as the national project.
The NMIJ also participated in the CCQM-K115 key comparison.
The NMIJ has a high purity material currently available as a CRM and listed in the JCTLM database.
A primary reference material (pure C-peptide), available from the NMIJ, is listed in the JCTLM database and was produced in compliance with ISO 15194 (also ISO Guides 34 and 35).
CRM Catalog 2014-2015, available on line at https://www.nmij.jp/english/service/C/CRM_Catalog_20140828.pdf [Accessed 6/18/2015].