McNeff C, Carr P W
Department of Chemistry, University of Minnesota, Minneapolis 55455, USA.
Anal Chem. 1995 Nov 1;67(21):3886-92. doi: 10.1021/ac00117a011.
The synthesis of an alkali-stable strong anion-exchange stationary phase by deposition of polyethylenimine (PEI), followed by cross-linking and quaternization, onto porous zirconia particles is described. Physical characterization of quaternized PEI-zirconia and PEI-zirconia shows that 50% and 24% of the amine groups are cross-linked, respectively. A plot of log k' versus log (competing ion concentration) is linear for three homopeptides, suggesting that ion exchange is the primary mechanism of retention on quaternized PEI-zirconia. Column efficiency for two 2,4-dinitrophenyl amino acids increased by 80% upon increasing the temperature from 50 degrees C to 100 degrees C. The hydrophobicity of quaternized PEI-zirconia was studied using a homologous series of p-alkoxybenzoic acids. For quaternized PEI-zirconia and PEI-zirconia, we found that the free energy of transfer of a methylene unit from the mobile phase to the stationary phase was -2.0 and -0.90 kJ/mol, respectively. The free energy of transfer of a methylene unit on quaternized PEI-zirconia is similar to that of a typical ODS phase (-2.4 kJ/mol). A van't Hoff plot for the above two 2,4-dinitrophenyl amino acids showed that the enthalpies of transfer are exothermic and fairly large (approximately -14 kJ/mol). Isocratic separations on quaternized PEI-zirconia of inorganic and organic anions are presented. Quaternized PEI-zirconia, quaternary amine-functionalized silica, and PEI-zirconia are compared chromatographically. Quaternized PEI-zirconia is more efficient than the silica-based phase in the separation of benzoic acid derivatives but slightly less efficient than PEI-zirconia. The major virtue of quaternized PEI-zirconia is that it is chemically stable in the pH range of 1-13 and is also stable at temperatures up to 100 degrees C.
本文描述了通过将聚乙烯亚胺（PEI）沉积在多孔氧化锆颗粒上，随后进行交联和季铵化反应，合成一种对碱稳定的强阴离子交换固定相的方法。对季铵化PEI-氧化锆和PEI-氧化锆进行的物理表征表明，分别有50%和24%的胺基发生了交联。对于三种同型肽，log k' 与log（竞争离子浓度）的关系图呈线性，这表明离子交换是季铵化PEI-氧化锆上保留的主要机制。当温度从50℃升高到100℃时，两种2,4-二硝基苯基氨基酸的柱效提高了80%。使用一系列对烷氧基苯甲酸研究了季铵化PEI-氧化锆的疏水性。对于季铵化PEI-氧化锆和PEI-氧化锆，我们发现亚甲基单元从流动相转移到固定相的自由能分别为-2.0和-0.90 kJ/mol。季铵化PEI-氧化锆上亚甲基单元的转移自由能与典型的ODS相（-2.4 kJ/mol）相似。上述两种2,4-二硝基苯基氨基酸的范特霍夫图表明，转移焓是放热的且相当大（约-14 kJ/mol）。给出了在季铵化PEI-氧化锆上对无机和有机阴离子的等度分离。对季铵化PEI-氧化锆、季胺功能化硅胶和PEI-氧化锆进行了色谱比较。在苯甲酸衍生物的分离中，季铵化PEI-氧化锆比硅胶基固定相更高效，但比PEI-氧化锆略低。季铵化PEI-氧化锆的主要优点是它在1-13的pH范围内化学稳定，并且在高达100℃的温度下也稳定。
