Analysis of Omeprazole within USP Methods

Importance of the Topic

Omeprazole is a widely prescribed proton-pump inhibitor (PPI) used in the management of gastric acid disorders. Reliable quantification according to pharmacopeial standards ensures product quality and patient safety. Reversed-phase liquid chromatography (RP-LC) remains the benchmark for routine analysis in quality control laboratories.

Study Objectives and Overview

This application note compares the United States Pharmacopeia (USP) official “Original” and “Fast” methods for omeprazole assay using Shim-pack GIST C8 columns. Key aims include:

• Evaluating chromatographic performance of two column dimensions.
• Assessing method speed and resolution.
• Demonstrating suitability for routine QC environments.

Methodology and Instrumentation

Both methods employ a reversed-phase C8 stationary phase and UV detection at 280 nm. Instrumentation details:

Instrumentation Used

• High-performance LC system: Shimadzu Nexera™ i / Nexera™-i
• Columns:
  • Original method – Shim-pack GIST C8, 150 × 4.6 mm, 5 µm
  • Fast method – Shim-pack GIST C8, 50 × 3.0 mm, 2 µm
• Mobile phase: Acetonitrile / 0.01 M sodium phosphate buffer (pH 7.6) at 1 : 3 (v/v)
• Flow rate: 0.80 mL/min (Original), 0.85 mL/min (Fast)
• Column temperature: 40 °C
• Injection volume: 20 µL (Original), 8 µL (Fast)
• Detection: UV 280 nm, cell temperature 40 °C

Main Results and Discussion

Both methods achieved baseline separation of omeprazole with sharp, symmetric peaks. Key findings:

• The 150 mm column provided robust retention and resolution within 10–12 minutes.
• The 50 mm column reduced analysis time by more than half, delivering results in under 5 minutes without compromising peak quality.
• Reproducibility of retention time and peak area was within USP acceptance criteria for both approaches.

Benefits and Practical Applications

• The original method suits laboratories prioritizing method robustness and extensive validation history.
• The fast method offers significant time savings and increased sample throughput, ideal for high-volume QC settings.
• Both protocols adhere to USP monograph requirements and can be integrated into existing workflows with minimal adjustments.

Future Trends and Potential Applications

Advances in column technology and UHPLC systems may further shorten analysis times and lower solvent consumption. Emerging trends include:

• Use of sub-2 µm and core-shell packing materials for enhanced speed and efficiency.
• Integration with automated sample preparation and data analytics for fully automated QC processes.
• Extension of the method to combination drug products and stability-indicating assays.

Conclusion

Both the USP original and fast RP-LC methods deliver reliable quantification of omeprazole in compliance with pharmacopeial standards. The fast variant significantly improves throughput, supporting modern laboratory demands without sacrificing performance.

References

• Shimadzu Corporation. ERAS-1000-0103, Application News L494 (JP, ENG), First Edition: Dec. 2021.