An Integrated Theory of Adsorption and Partition Mechanism and Eash Contribution to Solute Retention in Reversed Phase Liquid Chromatography

With the combination of the the stoichiometric displacement model for retention (SDM-R) in reversed phase liquid chromatography (RPLC) and the stoichiometric displacement model for adsorption (SDM-A) in physical chemistry,the total number of moles of the re-solvated methanol of stationary phase side.nr,and that of solute side in the mobile phase,q,corresponding the one mole of the desorbing solute,were separately determined and referred as the characterization parameters of the contributions of the adsorption mechanism and partition mechanism to the solute retention,respectively.A chromatographic system of insulin,using mobile phase consisting of the pseudo-homologue of alcohols(methanol,ethanol and 2-propanol)-water and trifluoroacetic acid was employed.The maximum number of the methanol layers on the stationary phase surface was found to be 10.6,only 3 of which being valid in usual RPLC,traditionally referred as a volume process in partition mechanism.However,it still follows the SDM-R.Both of q and nr of insulin were found not to be zero,indicating that the retention mechanism of insulin is a mixed mode of partition mechanism and adsorption mechanism.When methanol is used as the organic modifier,the ratio of q/nr was 1.13,indicating the contribution to insulin retention due to partition mechanism being a bit greater than that due to adsorption mechanism.A linear relationship between q,or nr and the carbon number of the pseudo-homologue in the mobile phase was also found.As a methodology for investigating the retention mechanism retention and behavior of biopolymers.a homologue of organic solvents as the organic modifier in mobile phase has also been explored.

An Integrated Theory of Adsorption and Partition Mechanism and Each Contribution to Solute Retention in Reversed Phase Liquid Chromatography

With the combination of the the stoichiometric displacement model for retention (SDM‐R) in reversed phase liquid chromatography (RPLC) and the stoichiometric displacement model for adsorption (SDM‐A) in physical chemistry, the total number of moles of the re‐solvated methanol of stationary phase side, nr, and that of solute side in the mobile phase, q, corresponding to one mole of the desorbing solute, were separately determined and referred as the characterization parameters of the contributions of the adsorption mechanism and partition mechanism to the solute retention, respectively. A chromatographic system of insulin, using mobile phase consisting of the pseudo‐homologue of alcohols (methanol, ethanol and 2‐propanol)‐water and trifluoroacetic add was employed. The maximum number of the methanol layers on the stationary phase surface was found to be 10.6, only 3 of which being valid in usual RPLC, traditionally referred as a volume process in partition mechanism. However, it still follows the SDM‐R. Both of q and nr of insulin were found not to be zero, indicating that the retention mechanism of insulin is a mixed mode of partition mechanism and adsorption mechanism. When methanol is used as the organic modifier, the ratio of q/nr was 1.13, indicating the contribution to insulin retention due to partition mechanism being a bit greater than that due to adsorption mechanism. A linear relationship between q, or nr and the carbon number of the pseudo‐homologue in the mobile phase was also found. As a methodology for investigating the retention mechanism retention and behaviors of biopolymers, a homologue of organic solvents as the organic modifier in mobile phase has also been explored.