Analysis of cefprozil and related impurities by reversed-phase liquid chromatography with UV detection

Importance of the Topic

Analysis of drug substance impurities is a critical component of pharmaceutical quality control and regulatory compliance. For β-lactam antibiotics like cefprozil, monitoring trace-level impurities ensures safety, efficacy, and consistency in manufacturing. Implementing a robust, pharmacopeia-compliant method supports batch release and stability testing of active pharmaceutical ingredients.

Aims and Overview of the Study

• Evaluate the European Pharmacopeia monograph procedure for quantifying cefprozil impurities.
• Demonstrate performance of the Thermo Scientific Vanquish Core HPLC system coupled with a Hypersil GOLD aQ column.
• Assess system suitability, sensitivity, repeatability, and method robustness for impurity profiling.

Methodology and Instrumentation

Sample preparation followed Ph. Eur. guidelines, generating a set of reference and test solutions in acidic phosphate buffer. Reversed-phase gradient chromatography was carried out on a Hypersil GOLD aQ (4.6×250 mm, 5 µm) column at 40 °C. Mobile phase A was 0.1 M ammonium dihydrogen phosphate (pH 4.4), B a 50/50 v/v mixture of phase A and acetonitrile. The gradient ramped from 19% to 64% B over 20 minutes and returned to initial conditions at 25 minutes. Detection occurred at 230 nm with a diode array detector.

Instrumentation Used:

• Vanquish Core HPLC system (quaternary pump, split sampler, column compartment, diode array detector)
• Thermo Scientific Chromeleon 7.3 CDS for data acquisition

Main Results and Discussion

System suitability testing with a mixed-impurity standard demonstrated baseline resolution (Rs >4.2) between cefprozil Z-isomer and impurity F, surpassing Ph. Eur. criteria. Peak asymmetries ranged 0.87–1.02. In standard test solutions, 26 total impurities were detected; six exceeded the 0.05% reporting threshold. Two impurities above 0.1% were identified as Impurity A and B by comparison with specific reference solutions. Repeatability studies yielded retention time RSD <0.1% and area RSD <0.4% for isomers and major impurities.

Benefits and Practical Applications

• Fully meets European Pharmacopeia monograph requirements without method adjustments.
• High resolution and precision support reliable impurity quantitation at regulatory thresholds.
• Suitable for routine batch-release and stability studies in pharmaceutical development.

Future Trends and Potential Applications

• Integration with mass spectrometry for structural confirmation of unknown impurities.
• Adoption of ultrahigh-performance LC to reduce analysis time and solvent consumption.
• Automation and digitalization for high-throughput impurity screening.
• Implementation of greener solvents and bufferless methods to improve sustainability.

Conclusion

The reversed-phase HPLC method based on the Ph. Eur. monograph was successfully implemented on the Vanquish Core system with Hypersil GOLD aQ column. The method delivered excellent resolution, sensitivity, and repeatability for cefprozil and its related impurities, ensuring compliance with regulatory purity limits.

Reference

1. Rai BP et al. Org. Process Res. Dev. 2014, 18, 662–664
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4. Barriere SL. Antimicrob. Newsletter 1992, 8, 21–24
5. ICH Q3A(R2): Impurities in New Drug Substances, 2008
6. Ph. Eur. Monograph 2342: Cefprozil Monohydrate, 9th edition, 2018