Limitations
The procedure works only for acids and bases with a large difference in solubility between their charged and their uncharged form. The procedure does not work for:
- Zwitterions with acidic and basic functional groups in the same molecule, e.g. glycine which tend to be water soluble at most pH.
- Very lipophilic amines that do not easily dissolve in the aqueous phase in their charged form, e.g. triphenylamine and trihexylamine.
- Very lipophilic acids that do not easily dissolve in the aqueous phase in their charged form, e.g. fatty acids.
- Lower amines like ammonia, methylamine, or triethanolamine which are miscible or significantly soluble in water at most pH.
- Hydrophilic acids like acetic acid, citric acid, and most inorganic acids like sulfuric acid or phosphoric acid.
Read more about this topic: Acid-base Extraction
Famous quotes containing the word limitations:
“To note an artists limitations is but to define his talent. A reporter can write equally well about everything that is presented to his view, but a creative writer can do his best only with what lies within the range and character of his deepest sympathies.”
—Willa Cather (18761947)
“... art transcends its limitations only by staying within them.”
—Flannery OConnor (19251964)
“That all may be so, but when I begin to exercise that power I am not conscious of the power, but only of the limitations imposed on me.”
—William Howard Taft (18571930)