Food Matrix Reference Materials for Hydrogen, Carbon, Nitrogen, Oxygen, and Sulfur Stable Isotope-Ratio Measurements: Collagens, Flours, Honeys, and Vegetable Oils

An
international project developed, quality-tested, and measured
isotope–delta values of 10 new food matrix reference materials
(RMs) for hydrogen, carbon, nitrogen, oxygen, and sulfur stable isotope-ratio
measurements to support food authenticity testing and food provenance
verification. These new RMs, USGS82 to USGS91, will enable users to
normalize measurements of samples to isotope–delta scales.
The RMs include (i) two honeys from Canada and tropical Vietnam, (ii)
two flours from C3 (rice) and C4 (millet) plants, (iii) four vegetable
oils from C3 (olive, peanut) and C4 (corn) plants, and (iv) two collagen
powders from marine fish and terrestrial mammal origins. An errors-in-variables
regression model included the uncertainty associated with the measured
and assigned values of the RMs, and it was applied centrally to normalize
results and obtain consensus values and measurement uncertainties.
Utilization of these new RMs should facilitate mutual compatibility
of stable isotope data if accepted normalization procedures are applied
and documented.