2D Analysis of Protein Therapeutics and Amino Acid Excipients with Combined UV and Charged Aerosol Detection

Importance of 2D Analysis of Protein Therapeutics and Amino Acid Excipients

Therapeutic protein formulations can undergo aggregation-driven phase transitions influenced by pH, temperature and concentration. Inclusion of select amino acid excipients such as arginine, histidine and methionine enhances stability by buffering, bulking or antioxidant action. A robust analytical method is essential to monitor both proteins and amino acid excipients in a single workflow.

Objectives and Study Overview

The study aimed to develop a two-dimensional liquid chromatography method for simultaneous separation of underivatized therapeutic proteins and common amino acid excipients. A mock formulation containing surfactant, protein, amino acids and ions was used to demonstrate proof of concept.

Methodology and Instrumentation

The integrated UHPLC platform combined:

• Dimension 1: reversed-phase separation on Thermo Scientific Accucore 150 C4 column (2.6 µm, 3.0×50 mm) with UV detection (DAD)
• Dimension 2: mixed-mode HILIC separation on Thermo Scientific Acclaim Trinity P1 column (3.0 µm, 3.0×100 mm) with Charged Aerosol Detection (CAD)
• Thermo Scientific UltiMate 3000 Dual Gradient system: DGP-3600RS pump, WPS-3000TRS autosampler, TCC-3000RS column oven, 6-port switching valve, Veo RS CAD

Results and Discussion

Precision for underivatized amino acids (proline, methionine, glycine, glutamic acid, aspartic acid, histidine, lysine, arginine) ranged 0.45–2.91 % RSD (n=6). CAD calibration curves over 0.1–1 µg on column achieved R2>0.985. In the mock formulation, DAD detected only the protein while CAD captured surfactant-free ions and amino acids across a broad dynamic range (ng to µg levels) in a single 20 min 2D run.

Benefits and Practical Applications

• Comprehensive monitoring of both chromophoric proteins and non-chromophoric excipients
• High sensitivity and wide dynamic range via CAD without derivatization
• Improved formulation screening and quality control for biotherapeutics

Future Trends and Potential Applications

Ongoing development may integrate higher-throughput 2D workflows, miniaturized columns and advanced detectors to screen a broader range of excipients and degradation products. Coupling with mass spectrometry and automated sample preparation will expand capabilities for detailed formulation characterization and stability testing.

Conclusion

The validated 2D UHPLC method with complementary UV and CAD detection enables simultaneous, precise analysis of therapeutic proteins and amino acid excipients. It offers a powerful tool for formulation development, QC and accelerated biopharmaceutical research.

Reference

Bailey B, Acworth I, Sneekes E-J, et al. 2D Analysis of Protein Therapeutics and Amino Acid Excipients with Combined UV and Charged Aerosol Detection. Thermo Fisher Scientific Application Note. 2015.