COMPARISON BETWEEN CALIXARENE AND CONVENTIONAL HPLC-STATIONARY PHASES CONCERNING WITH SEPARATION OF ANTIHYPERTENSIVE DRUGS

In this article, the effect of changes in different process variables such as pH, buffer type and concentration, column temperature, injection volume, as well as type and contents of organic modifier on retention behavior of seven antihypertensive drugs from two different categories (Angiotensin II receptor blockers and Diuretics) was investigated. Conventional RP-C18 column (Intersil (R) ODS-3) and calixarene column (Caltrex BIII (R)) were used as stationary phases. Calixarene-based stationary phases differ from the conventional RP-C18 in that they are as cyclodextrins in having cavities. The results showed that the examined conditions had different effects on the analytes retention on both columns, for example the elution order had changed and resolution between different analytes took variable behaviors. This can be attributed to the different chemical structures of both stationary phases used. The obtained results indicate that the used stationary phases behave as reversed phases packing and the hydrophobic interaction is main factor having a role in the retention of antihypertensive drugs. The chemical structure and properties of the analytes were found to have an effective role in their separation.