Countercurrent Chromatography

The preparative isolation of alkaloids can be achieved by means of modern countercurrent chromatogra-phy. Because of the ionic nature of the alkaloid systems with a controlled pH are preferred for the separation. Improved efficiency can be obtained by using ion pair gradients, e.g. solvent two-phase systems consisting of chloroform-methanol-aqueous

Table 5 General outline of reversed-phase high performance liquid chromatography systems for the separation of alkaloids

Stationary phase

C8, C18 or phenyl-bonded phase with low percentage of free silanol groups

Mobile phase

Ion supression mode

Methanol (acetonitrile)-water containing c. 0.01-0.1 mol L~1 phosphate buffer, ammonium carbonate or sodium acetate


Methanol (acetonitrile)-water containing c. 25-100 mmol L~1 alkylsulfonate and 1 % acid (e.g. acetic acid), pH 2-4

Table 6 General outlines of normal-phase high performance liquid chromatography systems for the separation of alkaloids

Stationary phase Mobile phase

Silica gel Dichloromethane,

Chloroform, Methanol Ammonia,

Diethyl/isopropyl ether, or Diethylamine or

Tetrahydrofuran, or Isopropanol Triethylamine Ethyl acetate (c. 1% of the mobile phase)

phosphate or citrate buffer, pH c. 4, containing per-chlorate, acetate or chloride as the ion pairing agent. High loadability and different selectivity compared with column chromatography are important features of countercurrent chromatography.

See also: III/Alkaloids: Gas Chromatography; Thin Layer (Planar) Chromatography. Natural Products: HighSpeed Countercurrent Chromatography.

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