Multivariate optimization approach for chiral resolution of drugs using human serum albumin in affinity electrokinetic chromatography-partial filling technique

Abstract

The enantiomeric resolution of chiral compounds using HSA by means of affinity EKC (AEKC)-partial filling technique is the result of a delicate balance between different experimental variables such as protein concentration, running pH (background electrophoretic buffer, protein and compound solutions) and protein solution plug length. In this paper multivariate optimization approaches for chiral separation of four basic drugs (alprenolol, oxprenolol, promethazine and propranolol) using HSA as chiral selector in AEKC-partial filling technique are studied. The experimental conditions to achieve maximum resolution are optimized using the Box-Behnken experimental design. Partial least squares and pareto charts are used to analyse the main effects on the resolution. The experimental resolutions observed for all compounds studied in optimum conditions agree with the estimated values based on response surface models. The results obtained show that the range of experimental conditions that provided enantioresolution narrows as hydrophobicity of analytes decreases. This fact can be explained by assuming that hydrophobicity controls the interaction of basic compounds with HSA.

Review of aqueous chiral electrokinetic chromatography (EKC) with an emphasis on chiral microemulsion EKC

“…Three publications by Martinez-Gomez et al [171][172][173] utilized HSA as a chiral selectand (affinity EKC) during the review period. The first report detailed the separation of oxprenolol enantiomers [171].…”

“…The highest resolution was 1.47 and the method was applied to commercial product analysis. The second study was expanded to include three additional chiral pharmaceuticals (alprenolol, propranolol, and promethazine) and multivariate optimization (Box-Behnken) [172]; pH, selector concentration, HSA plug length, and their cross-products were examined through experimental design (pareto charts, partial least squares regression, and multiple linear regressions performed) to increase resolution. Hydrophobic analytes required lower HSA concentrations and smaller plug lengths, whereas the opposite was found for more hydrophilic compounds.…”

Ion Exchange Resins as Excipients for Drug Delivery: Issues for Reproducible Drug Loading

“…It has been found that for the current system Amberlite TM IRP 69 / Propranolol HCl, the pH value in the drug solution is 6 and does not change -within experimental error -during the course of the experiments (data not shown). As the pK A value of PropH + is 9.45 [17], it is concluded that the drug persists mainly in its ionic form during experiments, and that the pH would not need special attention.…”

Characterisation of the Ion Exchange Reaction Between Propranolol-H+ or K+ with Amberlite™ IRP 69 Resin by Both, Isothermal Titration Calorimetry and (Flame) Photometric Equilibrium Analysis

“…The pK A value of PropH + is 9.45 [23], and all the solutions handled during experiments were in the pH range of between 5.9 and 6.3, which accounts for more than 99.9% of the molecules being dissociated. Moreover, chloride-ions are not considered to take part in the exchange process due to repulsive forces between chloride ions and the electric potential difference barrier (Donnan potential) which repel the co-ions from the ion exchanger.…”