Abstract
CCQM key comparison K-130 in the field of nitrogen mass fracton has been performed by the Inorganic Analysis Working Group (IAWG) of the Consultative Committee for Amount of Substance (CCQM).The aim of this key comparison CCQM-K130 is to support National Measurement Institutes (NMIs) and Designated Institutes (DIs) to demonstrate the validity of the procedures the employed for determination of nitrogen mass fraction in glycine. Mass fraction of nitrogen is very important pointer because the results of these measurements are often used for determination of protein mass fraction that is an important indicator of the quality of the vast majority of food products and raw materials, in particular dry milk powder. Proteins-enzymes catalyze chemical reactions, protein along with fats and carbohydrates is one of the indicators characterizing the energy value of food, so its definition is mandatory for all food products.The study material for this key comparison has been selected to be representative as one of the aminoacid - the simplest part of the protein. Glycine is an amino acid, single acid that does not have any isomers (melting point -290 °C; specific heat of evaporation - 528,6 J/kg; specific melting heat - 981,1 J/kg; pKa - 2, 34, molar mass - 75,07 g/mol, density - 1,607 g/cm3).Ural Scientific Research Institute for Metrology (UNIIM) acted as the coordinating laboratory of this comparison.Nine NMIs participated in this key comparison and one NMI participated in Pilot study that was condacted in parallel.Report A contains the results of key comparison and pilot study. The results of Pilot study were excluded from the Report BMain textTo reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).
Published Version
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