碱金属和碱土金属离子在反相高效液相色谱柱上的保留机理

发现以酒石酸和吡啶二甲酸等羧酸水溶液作淋洗剂时，钠，铵，钾，镁和钙等碱金属及碱土金属离子在ＯＤＳ反相高效液相色谱柱上有明显的保留，而且相互之间能达到一定程度的分离。单独用分配或疏水作用等反相高效液相色谱的保留机理难以解释其保留行为。为此，作者提出了动态包固定相机理，即认为羧酸根阴离子因其疏水性在ＯＤＳ固定相有保留，在固定相表面形成具有羧酸基阳离子交换树脂功能的动态包覆固定相。

Retention Mechanism of Alkali and Alkaline Earth Metal Ions on Reversed Phase High Performance Liquid Chromatographic Column

A study on the retention mechanism of cations (Na+, NH+4, K+, Mg2+and Ca2+) on reversed phase high performance liquid chromatography (RP-HPLC) column was made. The separation of cations (specially transition metals) on RP-HPLC column is based on forming some complexes or ion-pair compounds generally. In usual case, Na+, NH+4, K+, Mg2+ and Ca2+ can not be retained on RP-HPLC column because these cations can not form any stable complexes or ion-pair compounds with eluent anions used in this work. Experi- ment showed, however,that Na+, NH+4, K+, Mg2+ and Ca2+ could be separated on a RP- HPLC column (Zorbax ODS) when the mixture of tartaric acid (TA) and 2, 6-pyridinedi- carboxylic acid(PDC) was used as eluent. A dynamic coating stationary phase can be consid- ered. The eluents (TA and PDC) were retained on the ODS resins, and form a coating layer on the surface of the resins. The carboxylic groups on the coating layer act like the car- boxylic groups on cation-exchange resins. Consequently, Na+, NH+4, K+, Mg2+ and Ca2+ were separated on the ODS column like on the cation-exchange column.