Easy transfer of an EP method for chlorhexidine impurity analysis from a Shimadzu Nexera-i system to a Vanquish Core HPLC system

Significance of the topic

Liquid chromatographic method transfers are critical in regulated laboratories to ensure consistent and reliable impurity profiling across different instruments and sites. The transfer of compendial methods, such as the European Pharmacopoeia monograph for chlorhexidine impurity analysis, supports workload distribution, inter-laboratory harmonization, and replacement of legacy systems with modern HPLC platforms.

Objectives and Overview of the study

This work demonstrates the straightforward transfer of an EP monograph HPLC method for chlorhexidine digluconate impurity analysis from a Shimadzu Nexera-i system to a Thermo Scientific Vanquish Core Quaternary HPLC system. The focus is on achieving equivalent chromatographic results and exploiting the Vanquish Core’s adaptable gradient delay volume (GDV) features for retention time fine-tuning.

Methodology and Instrumentation

The chlorhexidine system suitability test (SST) standard (5 mg in 1 mL mobile phase A) was injected seven times on each instrument under identical conditions. Key reagents included 18.2 MΩ·cm water, Optima LC/MS acetonitrile, and LC-MS grade trifluoroacetic acid. Chromatographic separation employed a Hypersil GOLD C18 column (4.6×250 mm, 5 µm, 175 Å) with mobile phases A (0.1% TFA in water/acetonitrile 80/20 v/v) and B (0.1% TFA in water/acetonitrile 10/90 v/v). The gradient ran from 0% to 30% B over 54 min at 1 mL/min, column at 30 °C, autosampler at 8 °C, detection at 254 nm, 5 Hz (Vanquish) or 4.17 Hz (Nexera-i), and 7 µL injection. Data were acquired and processed with Chromeleon CDS 7.3.

Results and Discussion

Both systems produced very similar chromatograms with all specified impurities and unknown peaks meeting EP SST criteria (resolution > 8 for impurity pair L/G, peak-to-valley ratio > 6 for impurity B). The Vanquish Core system delivered improved precision: retention time RSD ≤ 0.05% vs ≤ 0.09% on the Nexera-i, and peak area RSD < 0.5% for all peaks. Slight absolute shifts in retention times (0.08–0.26 min earlier on Vanquish) were attributed to a smaller default GDV. Adjusting the Vanquish Core autosampler idle volume from 25 µL to 125 µL reduced the average retention time deviation from 0.132 min to 0.051 min. The optional 200 µL transfer kit loop further extends GDV up to 430 µL for fine tuning.

Benefits and Practical Applications of the Method

• Compliant and fully trackable method transfer without fluidic modifications.
• Improved system precision on the Vanquish Core platform.
• Flexible GDV adjustment enables rapid retention time alignment between instruments.
• Facilitates inter-instrument and inter-laboratory distribution of compendial methods.

Future Trends and Potential Applications

Development of software-driven GDV prediction tools could automate gradient delay compensation. Integration of AI for in silico method transfer and optimization may further streamline cross-platform harmonization. The approach can be extended to other EP and USP monographs and adapted for ultra-high-pressure systems.

Conclusion

The EP monograph method for chlorhexidine impurity analysis was successfully transferred from a Shimadzu Nexera-i to a Thermo Scientific Vanquish Core HPLC system. Equivalent chromatographic performance and superior precision were achieved. The Vanquish Core’s tunable GDV features enable rapid and compliant retention time matching, simplifying method transfer workflows.

Reference

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