The Determination of Alkaloids by Exchange of Ions

Abstract

The development of research on substances serving for the exchange of ions has been going on for about a century. Research workers were at first dependent only on substances of natural origin, but in the years 1910 to 1930 many experiments were made towards preparing suitable synthetic products. In 1935, Adams and Holmes1 prepared a new type of artificial resin, and thus, with this new group of substances, started development along new lines. Griessbach2 examined in detail the composition, action and theory of ion-exchange substances, also their preparation and the determination of their activity, and explained their wide use for metallurgical and chemical purposes, especially as water softeners and salt-removers. In principle we are concerned with two groups of artificial resins. The first includes the condensation products of formaldehyde with aromatic acids, chiefly polyhydric phenols, and natural products of the tannin type, these condensation products serving as exchangers of cations, or eventually of hydrogen ions. The second group is formed by the condensation products of aromatic amines with aldehydes, these products serving for the exchange of anions, including hydroxyl ions. Hesse3 deals, under the heading of chromatographic determination, with the exchange of ions in some detail, from both theoretical and practical standpoints. Similarly, Myers4 sees in the exchange of ions only one of the methods of chromatographic determination (see also Zechmeister5).