Deoxycholic acid method transfer from the Corona ultra RS Charged Aerosol Detector to the Corona Veo (or Vanquish) Charged Aerosol Detector

Significance of the Topic

The accurate measurement of deoxycholic acid and its impurities is critical in pharmaceutical quality control to ensure drug safety and compliance with compendial standards. Charged aerosol detection (CAD) has become a preferred universal detector for nonvolatile and semi-volatile analytes in HPLC, but newer detector models require clear guidance for method transfer to maintain performance and regulatory compliance.

Objectives and Study Overview

This study aimed to transfer the United States Pharmacopeia monograph method for deoxycholic acid (USP 40-NF 35) from the Thermo Scientific Corona ultra RS CAD to the newer Corona Veo or Vanquish CAD (VCAD). The goal was to optimize detector settings, confirm system suitability, and validate quantitative performance for both content and impurity determinations.

Methodology and Instrumentation

Reagents and standards were prepared using LC-MS grade acetonitrile, 0.1% formic acid in water and acetonitrile, and ultrapure water. USP reference standards of cholic acid and deoxycholic acid were used.

• Chromatographic system: Thermo Scientific Vanquish Flex UHPLC with quaternary pump, split sampler, column compartment, and Chromeleon software.
• Column: Acclaim 120 C18, 4.6 × 150 mm, 3 µm particle size.
• Mobile phase: A = 0.1% formic acid in water, B = 0.1% formic acid in acetonitrile; gradient from 75:25 to 0:100 over 24 min, then reequilibration.
• Flow rate: 1.0 mL/min; column temperature: 30 °C; injection volume: 25 µL.
• Detectors: Corona ultra RS CAD (PFV 1.00, filter 3 s, nebulizer at 25 °C) and Corona Veo/Vanquish CAD (PFV 1.20, filter 5 s, evaporation at 50 °C).

Standard and working solutions were prepared by serial dilution to achieve calibration points from 0.0005 to 0.01 mg/mL for deoxycholic acid and cholic acid.

Main Results and Discussion

System suitability tests met USP criteria on both detectors: relative standard deviation of peak area below 1% and signal-to-noise ratio above 30 for 0.01 mg/mL solutions, and SNR above 40 at 0.0005 mg/mL on the Veo CAD. Optimization steps included:

• Power Function Value set to 1.20 for best calibration linearity (R² > 0.9997) with 1/area² weighting.
• Evaporation temperature of 50 °C selected as a compromise between sensitivity and noise.
• Digital filter of 5 s chosen to enhance signal-to-noise without distorting peak shape.

Robustness was confirmed by doubling injection volume without adverse effects. Quantification of a 98% pure deoxycholic acid sample showed total impurity levels below 2% on both detectors. Minor differences in specific impurity responses were observed but did not affect overall compliance.

Benefits and Practical Applications

The transferred method on the Veo/Vanquish CAD offers equal or improved sensitivity, better signal-to-noise ratios, and reliable quantitation of both active compound and impurities. Laboratories upgrading from older CAD models can maintain USP compliance with minimal method revalidation effort. The optimized settings provide a robust workflow for routine pharmaceutical QC and research applications.

Future Trends and Opportunities

Advances in charged aerosol detection will continue to expand its applicability to complex matrices and trace-level analyses. Future developments may include automated method transfer tools, improved data processing algorithms for enhanced quantitation, and integration with multidimensional chromatography to address increasingly stringent regulatory requirements.

Conclusion

Successful transfer of the USP monograph method for deoxycholic acid from the Corona ultra RS CAD to the Corona Veo/Vanquish CAD was achieved by optimizing PFV, evaporation temperature, and digital filtering. The new detector model met all USP system suitability and performance criteria, demonstrating its readiness for compendial and routine pharmaceutical analysis.

References

1. Bailey B, Gamache PH, Acworth IN. Guidelines for Method Transfer and Optimization – from Earlier Model Corona Detectors to Corona Veo Detectors. Thermo Fisher Scientific Technical Note 1571; 2014.
2. Bailey B, Plante M, Thomas D, Crafts C, Gamache PH. Practical Use of CAD – Achieving Optimal Performance. In: Charged Aerosol Detection for Liquid Chromatography and Related Separation Techniques. Wiley; 2017. p. 163–189.
3. FDA Guidance for Industry: Bioanalytical Method Validation. U.S. Food and Drug Administration; May 2001.
4. Gamache PH, Kaufman SL. Principles of Charged Aerosol Detection. In: Charged Aerosol Detection for Liquid Chromatography and Related Separation Techniques. Wiley; 2017. p. 3–65.