Transfer of a compendial LC method for impurity analysis of chlorhexidine from a Waters Alliance HPLC system to a Vanquish Core HPLC system

Significance of the topic

Instrument-to-instrument transfer of compendial HPLC methods is a critical challenge in pharmaceutical and analytical laboratories, where consistency, regulatory compliance, and efficient workload distribution are essential. Chlorhexidine digluconate is a widely used antiseptic listed on the WHO Model List of Essential Medicines. Reliable impurity profiling according to the European Pharmacopoeia (EP) monograph ensures product safety and quality in medical, dental, and hygiene applications.

Objectives and overview

This study demonstrates the seamless transfer of an EP monograph method for chlorhexidine impurity analysis from a Waters Alliance quaternary HPLC system to a Thermo Scientific Vanquish Core HPLC system. The goal is to achieve equivalent chromatographic performance, meet EP system suitability criteria without method modification, and highlight any benefits in resolution and repeatability afforded by the modern instrumentation.

Methodology

The EP method employs a Hypersil GOLD C18 column (4.6 × 250 mm, 5 µm, 175 Å) with a binary gradient of 0.1 % trifluoroacetic acid in water/acetonitrile (80/20, v/v) to 0.1 % TFA in water/acetonitrile (10/90, v/v). The flow rate is 1 mL/min, column temperature 30 °C, and detection at 254 nm with a 6 nm bandwidth. Sample preparation follows the monograph: 5 mg of chlorhexidine impurity standard dissolved in 1 mL mobile phase A, with a 10 µL injection volume.

Instrumentation

• Waters Alliance Quaternary HPLC: Separation Module 2695, PDA Detector 2996, 10 mm flow cell.
• Thermo Scientific Vanquish Core HPLC: Quaternary Pump C, Split Sampler CT, Column Compartment C with passive pre-heater, Diode Array Detector CG, 11 µL flow cell.
• Thermo Scientific Chromeleon 7.3 software for data acquisition and analysis.

Main results and discussion

Chromatograms obtained on both systems under EP conditions show equivalent profiling of chlorhexidine and all specified impurities, with retention time deviations below 4 % and relative retention times matching EP values. The Vanquish Core system delivered sharper peaks and higher resolution due to reduced system dispersion volume. Resolution between critical pairs exceeded EP requirements (R > 8 vs. minimum 3), and peak-to-valley ratios surpassed 5 (EP threshold 2). Repeatability improved significantly: retention time RSDs ≤ 0.04 % on Vanquish Core versus up to 0.15 % on Alliance; area RSDs ≤ 0.5 % versus up to 2.8 %, respectively.

Benefits and practical applications

• Successful inter-instrument transfer without method modification or extensive revalidation.
• Maintained compliance with EP system suitability criteria.
• Enhanced resolution and precision using modern UHPLC-style hardware.
• Streamlined workflow for labs migrating from legacy systems or distributing assays across multiple instruments.

Future trends and applications

Advances in low-dispersion system architecture, automation kits for method transfer, and integration with advanced data systems will further simplify LC method migration. Adoption of UHPLC and core-shell column technologies will drive improvements in throughput and sensitivity. Emerging software tools and AI-driven chromatographic optimization promise to reduce transfer times and method development effort.

Conclusion

The EP monograph HPLC method for chlorhexidine impurity analysis was successfully transferred from a Waters Alliance system to a Thermo Scientific Vanquish Core system. Equivalent chromatographic performance was achieved, with notable gains in resolution and analytical repeatability on the Vanquish Core platform, supporting robust quality control and method portability.

Reference

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