Enantiomers of carboxylic acids have been separated with albumin as a chiral complexing agent in the mobile phase. Stereoselective separation has been obtained for different types of acids, in some cases with very high separation factor, as shown for di-p-toluoyltartaric acid (alpha(s) = 5.8). The stereoselectivity and retention properties depend on pH and on the concentration of albumin in the mobile phase. Retention can also be regulated by modifying the nature of the solid phase as well as by the use of additives in the mobile phase. Acids with low molar absorptivity, or with absorbance in the same wavelength range as albumin, can be detected by an indirect technique based on the use of a cationic mobile phase additive, such as 1-ethylquinolinium, which has high UV-absorptivity at a wavelength remote from that of albumin.
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