Capillary electrophoresis as an orthogonal technique in HPLC method validation.

Area of Science:

• Analytical Chemistry
• Pharmaceutical Science
• Chromatography & Electrophoresis

Background:

• High-performance liquid chromatography (HPLC) is standard for assaying drug substance/product purity and impurities.
• Method specificity, the ability to identify analytes amidst expected components, is a critical validation parameter.
• Existing HPLC methods with UV/MS detection often lack the resolution for challenging separations like isomers.

Purpose of the Study:

• To address the limitations of HPLC in achieving specificity for structurally similar compounds, particularly isomers.
• To explore the utility of capillary electrophoresis (CE) as an orthogonal technique to enhance specificity assessment.
• To integrate CE methods to improve the unequivocal identification of analytes in complex pharmaceutical matrices.

Main Methods:

• Utilized high-performance liquid chromatography with ultraviolet photodiode array detection and on-line mass spectrometry (LC-UVDAD-MS).
• Developed and applied a set of highly selective capillary electrophoresis (CE) methods.
• Employed CE orthogonally to HPLC for comprehensive specificity evaluation.

Main Results:

• LC-UVDAD-MS, while powerful, demonstrated limitations in resolving structural isomers due to similar molecular weights.
• Capillary electrophoresis provided high separation efficiency, complementing HPLC's capabilities.
• Orthogonal CE methods successfully addressed the specificity challenges unmet by LC-MS, particularly for isomer separation.

Conclusions:

• Capillary electrophoresis serves as a valuable orthogonal tool to enhance the specificity assessment of HPLC methods in pharmaceutical development.
• Integrating CE significantly improves the ability to unequivocally identify main compounds and impurities, including difficult-to-separate isomers.
• The combined approach of HPLC and CE offers a more robust strategy for ensuring drug quality and safety.