A polystyrenesulfonic acid resin in the hydrogen form is a useful stationary phase for chromatographicseparation of adenine, caffeine, theobromine, theophylline. tannic acid, xanthine and tea components with aqueous ethanol as eluent. The resulta indicated that caffeine, theophylline, theobromine, adenine, xanthine and tannic acid could be separated on a column of Dowex-50W-X8(H)"~by elution with 25% ethanol aa eluent.
L‐Ascorbic acid and oxalic acid could be successfully separated with a column of 8% cross‐linked sulfonated polystyrene cation‐exchange resin in hydrogen form, and eluted with 0.01% aqueous solution of nitric acid, sulfuric acid, or phosphoric acid. Among the mineral acids used, nitric acid showed the best separatory effect. The minimum detectable quantities of the acids were 0.05 μg and 0.5 μg per 0.5 ml sample solution for L‐ascorbic acid and oxalic acid, respectively. Under this condition, the acids could be detected by using automatic UV‐monitor apparatus.
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