Development of Rapid System for Ion-pair Reversed-phase Partition Mode HPLC by Using Hydrophilic Counter ion

提出了一种新的离子对反相分配模式的高效液相色谱分析方法，该方法利用缓冲液和碱金属离子等亲水性反离子。该方法具有洗脱速度快、分离效率高等优点。与传统方法相比，使用疏水反离子如季铵离子和长链烷基磺酸离子有明显的改进，例如，阴离子金属络合物与2，2‘-二羟基偶氮苯在6min内就能达到基线拆分，而用四丁基铵的常规法分离这些络合物需要30 mm。此外，该方法已成功地推广到4-(2-吡啶偶氮)间苯二酚及其类似物、多氨基甲酸(如Quin-2)和双羟丙酮类化合物的阴离子金属络合物。与传统方法相比，保留时间有了显著的改善。分离效率与四丁基铵离子相当，发现钠、锂、铯离子等碱性金属离子，四甲基铵离子等铵离子和金刚离子能有效地起到亲水反离子的作用。快速保留的机理归因于亲水离子的大小和水合作用，这导致了离子对的特殊性质。在所提出的带有亲水反离子的方法中，带电离子的保留机理也是基于类似于疏水反离子的离子对的分配。该方法为离子对反相分配模式的高效液相色谱提供了一种创新的体系。

A new method for HPLC with ion-pair reversed-phase partition mode has been developed by using hydrophilic counter ion such as buffer components and alkaline metal ion. The advantages of the proposed method are rapid elution and efficient separation. A marked improvement was attained compared with the conventional method by using hydrophobic counter ion such as quarternary ammonium ion and long chain alkylsulfonic ion.For example, anionic metal chelates with 2,2'-dihydroxyazobenzene resulted in base-line resolution within 6 min, In the conventional method with tetrabutylammonium on, it look 30 mm to separate these chelates. Furthermore, the proposed method has been successfully extended to the anionic metal chelates with 4-(2-pyridylazo) resorcinol and its analogues, polyaminocarboxylic acid such as Quin-2, and hydorazone derivatives. Compared to the conventional method, a significant improvement was achieved in retention time. The separation efficiency was comparable to that with tetrabutylammonium ion.It has been found that alkaline metal ions such as sodium, lithium and cesium ion, ammonium ion such as tetramethylammonium ion, and guanidium ion effectively work as the hydrophilic counter ion. The mechanism of the rapid retention is attributed to the size and hydration of the hydrophilic ion which leads to specific characteristics of the ion-pairs.The underlying retention mechanism of the charged anlyte in the proposed method with hydrophilic counter ion is also based on the partition of ion-pairs similar to that of hydrophobic counter ion. The proposed method serves as a innovative system for HPLC with ion-pair reversed-phase partition mode.