Correlation of Sulphonic Acid Retention Values in RP-IPC with Retention Values in RP-HPLC and Ion Chromatography

The logarithm of capacity factor lnk'ip in reversed-phase ion-pair liquid chromatography (RP-IPC) linearly deceases with methanol concentration (Cb), and the logarithm of capacity factor lnk'ic in ion-chromatography (IC) linearly decreases with the logarithm of salt concentration (lnCs). The intercept (Inkw ip, A) and slope (cip, B) values of a linear relationship between lnkip' vs. Cb in RP-IPC and lnk'ip vs. lnCs in IC were obtained. The logarithm of capacity factor in RP-HPLC and the logarithm of capacity factor in IC, the solute charges and the parameter B in IC have been selected as the descriptors of solute molecular and electrostatic interaction respectively. It has been observed that the logarithm of capacity factors the parameters lnk and cip in RP-IPC can be well correlated with the logaríthm of capacíty factors in RP-HPLC and the logarithm of capacity factors in IC, the solute charges and the parameter B. Both the lnkRP in RP-HPLC and the lnkic in IC, the solute charges and the parameter B made a positive contribution to the retention and the parameter inkj in RP-PC, but made a negative contribution to the parameter cip in RP-IPC. It can be concluded that both the molecular and the electrostatic interaction play major role in retention of the ionic solutes in RP-IPC.