Improvement of electrophoretic enantioseparation ofamlodipine by polybrene

In chiral and non-chiral electrophoretic resolution of basic drugs, adsorption of analytes to negatively charged capillary wall could lead to poor repeatability of migration time and peak area. In addition, chiral resolutions of basic drugs are commonly performed in low pH buffers. Therefore, longer analysis time due to suppression of electroosmotic flow [EOF] is another dilemma. In this work the improvement effect of polybrene [PB], a cationic polymer, on chiral separation of a model basic drug, amlodipine [AML], was investigated. PB both as a semi-permanent coating agent and as an additive in the running buffer was utilized. Better results were obtained with PB as a buffer additive. Compare to untreated bare silica without using PB in running buffer, addition of 0.0005% PB to buffer decreased analysis time downed to 3 folds; efficiency improved up to 5 folds; limit of detection [LOD] and limit of quantification [LOQ] downed to 8 folds and within-day migration time and peak area repeatabilities, in terms of relative standard deviations [RSD] downed to 5 and 20 folds, respectively

Effect of capillary rinsing proctol on the reproducibility of separation in capillary electrophoresis with indirect UV detection

Capillary electrophoresis [CE] with indirect UV detection is an interesting analytical method for the analysis of drugs and pharmaceuticals. Good and reproducible capillary quality is needed to develop robust methods and to facilitate method transfer in CE. It is widely accepted that preconditioning procedures are indispensable in capillary electrophoresis in order to achieve reproducibility of migration times and peak areas. In order to explore different aspects of this technique, a set of experiments were performed using vigabatrin as a model drug. The effects of capillary rinsing between each run was investigated using basic [NaOH 0.1 M] and acidic [phosphoric acid 0.1 M]-wash cycles. The results of 10 consecutive injection of the model drug after each of the two wash cycles, reveal that more reproducible results obtained when acid-wash cycle was performed as a capillary conditioning protocol. The higher pH changes during basic-wash cycle and its effects on the characteristics of the capillary inner surface were suggested as a source of greater variation between consecutive runs