Chiral capillary zone electrophoresis in enantioseparation and analysis of cinacalcet impurities: Use of Quality by Design principles in method development

Abstract

A capillary electrophoresis method for the simultaneous determination of the enantiomeric purity and of 30 impurities of the chiral calcimimetic drug cinacalcet hydrochloride has been developed following Quality by Design 31 principles. The scouting phase was aimed to select the separation operative mode and to identify a suitable chiral 32 selector. Among the tested cyclodextrins, (2-carboxyethyl)-β-cyclodextrin and (2-hydroxypropyl)-γ-cyclodextrin 33 (HPγCyD) showed good chiral resolving capabilities. The selected separation system was solvent-modified capillary 34 zone electrophoresis with the addition of HPγCyD and methanol. Voltage, buffer pH, methanol concentration and 35 HPγCyD concentration were investigated as critical method parameters by a multivariate strategy. Critical method 36 attributes were represented by enantioresolution and analysis time. A Box-Behnken Design allowed the contour plots to 37 be drawn and quadratic and interaction effects to be highlighted. The Method Operable Design Region (MODR) was 38 identified by applying Monte-Carlo simulations and corresponded to the multidimensional zone where both the critical 39 method attributes fulfilled the requirements with a desired probability π≥90%. The working conditions, with the MODR 40 limits, corresponded to the following: capillary length, 48.5 cm; temperature, 18 °C; voltage, 26 kV (26-27 kV); 41 background electrolyte, 150 mM phosphate buffer pH 2.70 (2.60-2.80), 3.1 mM (3.0-3.5 mM) HPγCyD; 2.00% (0.00- 42 8.40%) v/v methanol. Robustness testing was carried out by a Plackett-Burman matrix and finally a method control 43 strategy was defined. The complete separation of the analytes was obtained in about 10 min. The method was validated 44 following the International Council for Harmonisation guidelines and was applied for the analysis of a real sample of 45 cinacalcet hydrochloride tablets.