APRO-1: Certified Reference Material of L-proline

The following tables show those constituents for which certified and information values have been established for this L-proline pure substance certified reference material (CRM).

The certified value represents the purity of L-proline and is based on results from data generated at NRC using quantitative proton nuclear magnetic resonance spectroscopy (1H-qNMR). The expanded uncertainty (UCRM) in the certified value is equal to U = kuc where uc is the combined standard uncertainty calculated according to the JCGM Guide [1] and k is the coverage factor. A coverage factor of two (2) was applied for L-proline. It is intended that UCRM accounts for every aspect that reasonably contributes to the uncertainty of the certified value.

Table 1: Certified value for APRO-1

Substance Molecular formula Mass fraction g/g
L-proline (a) C5H9NO2 0.9957 ± 0.0050

Table 2: Information values for impurities in APRO-1

Substance Molecular formula Mass fraction g/g
isoleucine (b) C6H13NO2 5.1 ×10–7
leucine (b) C6H13NO2 2.8 ×10–6
valine (b) C5H11NO2 2.5 ×10–5


The coding refers to the instrumental method of analyte determination.

  • a - Quantitative proton nuclear magnetic resonance spectroscopy (1H-qNMR)
  • b - Liquid chromatography tandem mass spectrometry (LC‑MS/MS)

Intended use

This reference material is primarily intended for use in the calibration of procedures and the development of methods for the determination of L-proline. A minimum sample mass of 10 mg is recommended.

Storage and sampling

It is recommended that the material be stored in a controlled cold temperature environment such as a refrigerator between 2 to 8°C. After use the bottle should be tightly closed and stored properly.


Included in the combined uncertainty estimate (uc) are uncertainties in the batch characterization (uchar), uncertainties related to possible between-bottle variation (uhom), uncertainties related to stability (ustability) and uncertainties related to variability between different qNMR signals (umethod). Expressed as standard uncertainties, these components are listed in Table 3.

Table 3: Uncertainty components for APRO-1

Substance Uk=2
L-proline 0.0050 0.0025 0.0019 0.0015 0.0000 0.00062

Date of issue: January 2018
Date of expiry: January 2023

Date modified: