Parallel analysis of drug product for assay and related substances determination

Importance of the Topic

The routine quality control of pharmaceuticals demands rapid and reliable methods for measuring both active ingredients and related impurities. Simultaneous determination of assay and impurity levels accelerates product release decisions, reduces resource consumption, and minimizes human error in high-throughput laboratories.

Study Objectives and Overview

This application note evaluates the performance of the Thermo Scientific Vanquish Duo for Dual LC system by conducting parallel analyses of metformin hydrochloride tablets. The study compares simultaneous assay and related substances testing against traditional single-channel (U)HPLC workflows to demonstrate improvements in throughput, bench space use, and operational efficiency.

Methodology

Sample Preparation and Chromatography Conditions:

• Assay and impurity methods used a Phenomenex HyperClone BDS C18 column (250 × 4.6 mm, 5 µm).
• Mobile phase was 90:10 phosphate buffer (pH 3.85)/acetonitrile, isocratic at 1.0 mL/min.
• Assay run time 15 min, related substances run time 30 min; UV detection at 218 nm.
• Standard and sample solutions were prepared at 125 µg/mL for assay and 1.25 mg/mL for impurity profiling.

Instrumental Setup

Vanquish Flex Duo for Dual LC system with:

• Two independent UHPLC flow paths (dual pump, dual sampler, dual detector).
• Vanquish Diode Array Detectors and Chromeleon 7.2.10 for data handling.
• Shared solvents and a single column compartment to optimize bench space.

Main Results and Discussion

Assay performance met system suitability criteria with tailing factor ≤1.61, theoretical plates >16 000, and RSD of peak area ≤0.05%. Metformin content in three tablet samples ranged from 97.1 to 98.2% (specification 95–105%).

Related substances analysis achieved LOD/LOQ of 0.02/0.04% for metformin and 0.004/0.008% for 1-cyanoguanidine. All unknown and known impurities remained below 0.1%, with total impurities below 0.2%, satisfying regulatory thresholds.

Simultaneous dual-channel operation doubled throughput without additional bench footprint or staff, reducing sample vial usage and solvent preparations.

Practical Benefits and Applications

Running assay and impurity tests in parallel on one instrument enables faster product release, lowers operational costs, and simplifies laboratory workflow. This approach is particularly beneficial for high-throughput QA/QC environments, method development, robustness testing, and mass balance studies requiring multiple detectors.

Future Trends and Potential Applications

Advancements may include integration of mass spectrometry or charged aerosol detection for broader impurity profiling, automated method optimization powered by AI, and miniaturized dual-flow systems for point-of-care or field testing. Expansion into multi-dimensional chromatography and real-time release testing could further streamline pharmaceutical analysis.

Conclusion

The Vanquish Duo for Dual LC system enables parallel assay and impurity analysis of metformin hydrochloride, doubling laboratory throughput while maintaining chromatographic performance and meeting all system suitability and regulatory criteria. This dual-channel concept enhances productivity and supports rapid decision-making in pharmaceutical quality control.

References

• Thermo Fisher Scientific. Vanquish Duo UHPLC Systems Brochure, BR72623, 2022.