High speed analysis of paracetamol and its process impurities

Significance of the topic

Paracetamol is one of the most commonly used analgesic and antipyretic drugs worldwide. Ensuring rapid, sensitive, and high-resolution analysis of paracetamol and its process-related impurities is essential for pharmaceutical quality control and regulatory compliance.

Objectives and Study Overview

This study presents a high-speed UHPLC gradient method using sub-2 µm particle columns to separate paracetamol, nine process impurities, and one degradation product in under two minutes. The method aims to accelerate routine QC analysis while maintaining accuracy and reproducibility.

Methodology and Instrumentation

Sample Preparation:

• Homogenize 100 mg of drug formulation.
• Extract with 80 ml of 50% water-methanol under ultrasonication for 20 minutes.
• Cool, dilute to 100 ml with water, and filter through a 0.45 µm syringe filter.

Standard Solutions:

• Dissolve 0.2 g of each analyte in 10 ml methanol.
• Serially dilute to achieve 0.020 mg/ml in mobile phase.

Chromatographic Conditions:

• Column: BlueOrchid 120-1.8 C18, 100 × 2 mm.
• Mobile Phase: A = acetonitrile, B = phosphate buffer pH 3.7.
• Gradient: 0–0.30 min at 13% A; ramp to 70% A by 2.00 min; hold to 2.50 min.
• Flow Rate: 0.8 ml/min; Temperature: 50 °C; Injection: 1 µl; Pressure: ~870 bar.
• Detection: UV at 245 nm, 100 Hz, 0.005 s response.

Instrumentation:

• KNAUER PLATINblue UHPLC system with dual Pump P-1, Degasser M-1, SmartMix 100, Autosampler AS-1, Column Oven, Detector MW-1, and ChromGate software.

Results and Discussion

The UHPLC method achieved baseline separation of paracetamol and ten related compounds in under 2 minutes, outperforming conventional HPLC methods by 3–15× in speed. Key performance metrics:

• Retention time RSD: 0.1–0.7% (n=5).
• LOD: 0.01–0.08 µg/ml (S/N=3).
• Linearity: r2 = 0.999885–0.99993 over 0.1–100 ng.
• Solvent consumption reduced by >80% per run.

The method detected the degradation product 4-aminophenol at 0.02% w/w in a formulation, demonstrating high sensitivity and selectivity.

Benefits and Practical Applications

• Ultra-fast throughput for QA/QC laboratories.
• Enhanced resolution and sensitivity for impurity profiling.
• Significant reduction in analysis time, sample volume, and solvent usage.
• Robust reproducibility suitable for routine process monitoring.

Future Trends and Opportunities

Integration of sub-2 µm UHPLC columns with mass spectrometric detection could broaden impurity characterization. Online sampling and advanced data analytics promise real-time process control. Ongoing miniaturization and greener solvent systems may further accelerate and sustainable analytical workflows.

Conclusion

The described UHPLC method combining a BlueOrchid sub-2 µm column with a PLATINblue system delivers ultra-fast, reliable separation of paracetamol and its impurities. This approach supports high-throughput pharmaceutical QC with improved performance and reduced operational costs.

References

1. Nageswara Rao R.; Narasaraju A. Analytical Science, Vol. 22, 287–292 (2006)
2. Nageralli B.S.; Seetharamappa J.; Gowda B.G.; Melwanki M. Journal of Chromatography B, Vol. 798, No. 1, 49–54 (2003)
3. European Pharmacopoeia Monograph Paracetamol 01/2005:0049
4. KNAUER, Applications Journal V7801, 07/2008, 79