Weisz Adrian, Idina Ana, Ben-Ari Julius, Karni Miriam, Mandelbaum Asher, Ito Yoichiro
Office of Cosmetics and Colors, Center for Food Safety and Applied Nutrition, US Food and Drug Administration, College Park, MD 20740, USA.
J Chromatogr A. 2007 Jun 1;1151(1-2):82-90. doi: 10.1016/j.chroma.2007.03.085. Epub 2007 Mar 30.
This work involves the preparative separation of some isomeric dicarboxylic acids using pH-zone-refining counter-current chromatography (CCC), a relatively new preparative technique for the separation of ionizable compounds. The paper concentrates especially on the separation of a synthetic mixture of closely related cis and trans pairs of 1-methyl- and 1,3-dimethyl-1,3-cyclohexanedicarboxylic acids. The elution sequence of the isomers is discussed in terms of their relative acidities (pK(a) values) in solution and gas phase, hydrophobicities, and steric configuration. Two possible explanations are suggested for the mechanism of separation. They both involve the amount of retainer acid used, as it affects the separation and plays a role in the chemohydrodynamic equilibrium of the dicarboxylic acids in the column.
这项工作涉及使用pH区带精制逆流色谱法（CCC）对一些异构二元羧酸进行制备分离，这是一种用于分离可电离化合物的相对较新的制备技术。本文特别专注于分离密切相关的顺式和反式1-甲基-1,3-环己烷二甲酸以及1,3-二甲基-1,3-环己烷二甲酸的合成混合物。根据异构体在溶液和气相中的相对酸度（pK(a)值）、疏水性和空间构型讨论了异构体的洗脱顺序。针对分离机制提出了两种可能的解释。它们都涉及所用保留酸的量，因为它会影响分离并在柱中二元羧酸的化学流体动力学平衡中起作用。
