Capillary electrophoresis (CE) is widely used for the impurity profiling of drugs that contain stereochemical centers in their structures, analysis of biomolecules, and characterization of biopharmaceuticals. It skillfully separates, identifies, and quantifies various compounds, offering advantages over conventional methods. The allure lies in its proficiency in drug impurity profiling and handling complex mixtures.
Fig. 1 Instrumentation of CE (Shah M, Patel N, Tripathi N, Vyas VK)
CE is a chromatographic technique that separates ions based on their charge and size. It utilizes a fused silica capillary as the separation column, where an electric field is applied across the capillary to drive the charged species through a buffer-filled capillary. As the analytes migrate through the capillary, they separate based on their electrophoretic mobility and reach the detector at different times. The detector records the separation peaks, and the data are then analyzed to identify and quantify the analytes.
Types of Capillary Electrophoresis
Following are several types of capillary electrophoresis methods, each catering to specific separation needs:
Capillary Zone Electrophoresis (CZE): CZE stands as the ideal choice when it comes to analyzing small, charged molecules, and ions.
Capillary Gel Electrophoresis (CGE): CGE is a choice for distinguishing large biomolecules like proteins and nucleic acids. This ingenious approach involves a gel-filled capillary, ingeniously creating a sieving effect that sorts analytes based on both their charge and size, unveiling a comprehensive and precise separation.
Capillary Isotachophoresis (CITP): CITP proves highly advantageous for samples spanning a wide range of concentrations. It employs a stacking technique that effectively concentrates analytes into distinct zones, improving sensitivity and resolution.
Capillary Isoelectric Focusing (CIEF): CIEF boasts the remarkable ability to segregate analytes according to their isoelectric points, making it a valuable technique for scrutinizing intricate protein mixtures.
Applications of Capillary Electrophoresis for Impurity Profiling of Drugs
In the vast realm of pharmaceutical applications, CE shines as a versatile tool, particularly in the arena of drug impurity profiling, some key applications include:
Identification of Impurities: The remarkable capabilities of CE shine brightest in its ability to accurately identify and quantify impurities within drug formulations, ensuring compliance with regulatory standards and pharmacopeial monographs.
Chiral Separation: CE reigns supreme in its unmatched efficacy at resolving enantiomers (mirror-image isomers) of chiral drugs, which is crucial because enantiomers often exhibit different pharmacological activities.
Stability Studies: CE proves to be a valuable tool in the stability studies, it allows for the thorough examination of drug formulations' stability and enables the monitoring of degradation product formation over time, ensuring the longevity and reliability of pharmaceutical products
Comparison of Capillary Electrophoresis with Liquid Chromatography for Drug Impurity Profiling
Within the realm of drug impurity profiling, liquid chromatography (LC) stands as another widely employed technique. LC boasts impressive attributes such as high resolution and sensitivity. However, in this grand arena, CE emerges as a strong contender, bringing forth several advantages that set it apart:
Analysis Time: CE typically demands shorter analysis times, Analysis Time: CE typically requires shorter analysis times, leading to increased efficiency and reduced operational costs.
Sample Size: In the realm of capillary electrophoresis, smaller sample volumes become pivotal, particularly when handling limited or precious samples.
Automation: CE offers effortless automation, paving the way for elevated sample throughput and diminished human errors.
Versatility: CE exhibits a vast analytical prowess, capable of scrutinizing a diverse spectrum of analytes encompassing small ions, large biomolecules, and chiral compounds. This remarkable versatility often exceeds the capabilities of LC, offering a comprehensive and all-encompassing analytical approach.
Reference
- Shah M, Patel N, Tripathi N, Vyas VK. Capillary electrophoresis methods for impurity profiling of drugs: A review of the past decade. J Pharm Anal. 2022, 12(1):15-28
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