Silica gel for chromatography has been subjected to chemical pretreatment with aqueous NaOH and KOH solutions. The surface-phase pH, surface area, Na+ and K+ ion content and H+-ion exchange capacity of the samples have been determined. Sorption–desorption studies of the amino acids, l(+)-arginine and l(–)-histidine, were carried out from 90% ethanol solution on substrates whose surface-phase pH was in the range 7.0–11.5. Sorption was found to be pH-dependent, with maximum sorption occurring over the pH range 7.5–10.0. The process was fast (10 min to 24 h) and almost athermic (20–50°C). The desorption efficiency and retarding influence of metallic cations on the adsorption were in the order: Th4+ > Al3+ > Mg2+ > Na+. Elution studies and column chromatography of a few synthetic amino acid mixtures have also been carried out.
