A GUIDE TO CAROTENOID ANALYSIS IN FOODS

36 A Guide to Carotenoid Analysis in Foods
Don’ts
• Do not leave or store carotenoids in dichloromethane,
ethyl ether, or acetone because they degrade
faster in these solvents. When not in use,
carotenoids should be left in petroleum ether or
hexane or dry, under vacuum or nitrogen.
• Do not use blenders with plastic cup. Acetone corrodes
plastic, and carotenoids adhere to plastic
easily and tightly.
• Do not saponify, unless it is absolutely necessary,
to avoid structural changes and degradation of carotenoids.
If needed, the mildest conditions that can
accomplish its purpose should be used (e.g., saponifying
carotenoids dissolved in petroleum ether
with equal volume of 10% methanolic potassium
hydroxide, at room temperature in the dark overnight).
• Do not shake the separatory funnel during partition
to avoid forming an emulsion.
• Do not let extracts containing chlorophyll (e.g.,
extracts of green vegetables) or other potential
sensitizers stand even for a brief period, especially
when exposed to light. Photodegradation and
isomerization occur very rapidly under such conditions.
• Do not quantify overlapping peaks in the HPLC
chromatogram. The accuracy of the quantitative
data depends directly on how accurately the peak
areas are known. Efficient columns are now available,
and in the right combination with the mobile
phase, give baseline or near baseline separations
of at least the major carotenoids.