To aliquot is to split something up into smaller parts.
This is used in science quite often.
For example, a reagent that is to be kept frozen, but is not stable and needs to be used often should be aliquoted into appropriate quantities. This saves the reagent from degrading due to frequent thawing and makes it easier to use.
The word aliquot has become more common in the laboratory, and can now simply mean a small quantity. It is usually, but not exclusively, used for liquids.