Asymmetric Adsorption of Alanine by Quartz Powder from Ethanol Solution

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Abstract
The asymmetric adsorption of the racemic alanine by the optically active quartz from ethanol solution at 8 °C was studied by the 14C-tracer method and the newly developed 14C-tracer·ninhydrin-colorimetry combination method. The preferential adsorption of l-alanine by levorotatory quartz (l-quartz) and d-alanine by dextrorotatory quartz (d-quartz) was confirmed. The asymmetric adsorptivity (As) falls in the range of 1.1–1.3, which is comparable with the value determined at −80 °C in the previous paper. The effects of water content in the ethanol solution and of the adsorption temperature upon the adsorption affinity of alanine to quartz were also measured. The cause for the asymmetric adsorption is discussed from the crystallographic point of view.