Caffeine reference material certified for purity is produced worldwide, but no research
work on the details of the certification process has been published in the literature. In this
paper, we report the scientific details of the preparation and certification of pure caffeine
reference materials. Caffeine was prepared by extraction from roasted and ground coffee
by dichloromethane after heating in deionized water mixed with magnesium oxide. The
extract was purified, dried, and bottled in dark glass vials. Stratified random selection was
applied to select a number of vials for homogeneity and stability studies, which revealed
that the prepared reference material is homogeneous and sufficiently stable. Quantification
of caffeine purity % was carried out using a calibrated UV/visible spectrophotometer
and a calibrated high-performance liquid chromatography with diode-array detection
method. The results obtained from both methods were combined to drive the certified
value and its associated uncertainty. The certified value of the reference material purity
was found to be 99.86% and its associated uncertainty was ±0.65%, which makes the
candidate reference material a very useful calibrant in food and drug chemical analysis.
Copyright © 2016, Food and Drug Administration, Taiwan. Published by Elsevier Taiwan
LLC. This is an open access article under the CC BY-NC-ND license