Validatibility of a capillary isoelectric focusing method for impurity quantitation

Area of Science:

• Analytical Chemistry
• Biopharmaceutical Analysis
• Method Validation

Background:

• Quantifying product-related impurities is crucial for protein drug substance quality.
• Capillary isoelectric focusing (cIEF) is a potential technique for impurity analysis.
• International Council for Harmonisation (ICH) guidelines provide a framework for analytical method validation.

Purpose of the Study:

• To examine the validatability of a capillary isoelectric focusing (cIEF) method for quantifying protein drug impurities.
• To demonstrate the suitability of cIEF for analyzing specific impurities like deamidated and aggregated forms.
• To apply International Council for Harmonisation (ICH) validation guidelines to the cIEF method.

Main Methods:

• Generated impurity standards by spiking deamidated and aggregated protein impurities into a drug substance.
• Analyzed six impurity spike levels (0.5-12% and 0.5-8%) in triplicate.
• Calculated specificity, accuracy, precision, linearity, and limit of quantitation (LOQ) based on impurity peak area percent.

Main Results:

• Demonstrated high accuracy (85-97%) and linearity (r²=0.9994, 0.9827) for both impurity types.
• Achieved low relative standard deviation (RSD) for precision (<6% repeatability, <20% intermediate precision/reproducibility).
• Established the limit of quantitation (LOQ) at 0.5% for both deamidated and aggregated impurities.

Conclusions:

• The cIEF method is validated and suitable for quantifying product-related impurities in protein drug substances according to ICH guidelines.
• cIEF proves to be a reliable analytical technique for impurity quantitation in biopharmaceuticals.
• This strategy successfully applies ICH validation principles to cIEF impurity analysis.