Recovery of Cytokinins from Cation Exchange Resins

Cytokinins exhibit great affinity for the polystyrene matrix of Dowex-50 cation exchange resins. Model experiments showed that only c. 20% of the applied 2-methylthio-trans-zeatin and c. 70% of the trans-zeatin are eluted from AG 50W columns with six bed volumes of 1 N NH₄ OH. Inclusion of 70% (v/v) ethanol in the eluant increases the recovery to c. 55 and 85% respectively. No additional recovery was obtained upon continued elution to 14 bed volumes. Similar experiments with Duolite CS-101, a weak acid cation exchange resin with acrylic matrix, showed that c. 95% of the applied 2-methylthio derivatives of isopentenyladenine and zeatin are recovered from the resin with six bed volumes of 70% (v/v) ethanol (pH 10) or 1 N NH₄OH in 70% (v/v) ethanol. The less modified cytokinins, isopentenyladenosine and ribosylzeatin, are recovered completely under these conditions. Recovery of cytokinins was determined by means of high-pressure liquid chromatography of the column eluates.