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

Ionpairmode

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.

Solar Panel Basics

Solar Panel Basics

Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.

Get My Free Ebook


Post a comment