Advancing Sensitivity and Efficiency in Released N-Linked Glycan Analysis With the ACQUITY™ QDa™ II Mass Detector

Importance of the Topic

Glycosylation is a critical post-translational modification influencing protein folding, stability, efficacy, and immunogenicity of therapeutic monoclonal antibodies. Consistent glycan profiling is essential for process control and quality monitoring in biopharmaceutical manufacturing, as variations can affect safety and therapeutic performance.

Study Objectives and Overview

This application note evaluates the performance of the ACQUITY QDa II single quadrupole mass detector in released N-linked glycan analysis.

• Assess sensitivity and specificity improvements compared to fluorescence detection
• Demonstrate generation and reproducibility of glucose unit calibration curves for retention time standardization
• Illustrate detection and quantitation of low-abundance impurities, notably high mannose species such as Man-5
• Showcase integration with Empower software for streamlined QC workflows

Methodology and Instrumentation

Glycans were enzymatically released from monoclonal antibodies, labeled using the RapiFluor-MS kit, and separated by HILIC on an ACQUITY Premier Glycan BEH Amide column. Dual detection employed:

• Fluorescence detector at excitation 265 nm and emission 425 nm
• ACQUITY QDa II single quadrupole mass detector operating in positive ESI mode with an acquisition range of 350–1500 m/z, capillary voltage 1.5 kV, cone voltage 20 V, and probe temperature 500 °C

Key Results and Discussion

Glucose unit (GU) Calibration
• A dextran ladder calibrated GU values with a cubic spline fit, covering GU 4–12 for broad glycan coverage
• Experimental GU values matched expected values within 0.1 GU and historical data within 0.05 GU, demonstrating high reproducibility

Extended Mass Range and Charge State Simplification
• The QDa II detector’s extended m/z range up to 1500 enabled analysis of 19 glycan species in a single [M+2H]2 charge state
• This uniform charge state simplified data interpretation and improved sensitivity for larger glycans

High Mannose Impurity Monitoring
• Retention time and mass of Man-5 glycans were established using a high mannose test standard
• In a representative mAb sample, fluorescence detection showed a coeluted unknown species at the Man-5 retention time
• Selected ion recording at m/z 774.21 enhanced specificity, revealing low-level Man-5 impurity undetectable by fluorescence alone

Benefits and Practical Applications

• Enhanced sensitivity and specificity for routine glycan profiling in QC laboratories
• Seamless integration with existing Empower software for compliant data acquisition and reporting
• Compact and energy-efficient detector design supports sustainable lab practices and cost savings
• Improved monitoring of critical quality attributes such as high mannose glycans to ensure therapeutic consistency

Future Trends and Potential Applications

As biopharmaceutical characterization evolves, single quadrupole detectors like the ACQUITY QDa II will play a greater role in:

• Automated, high-throughput glycan screening during early-stage development
• Integration with orthogonal analytical techniques for comprehensive glycoform profiling
• Real-time release testing in continuous manufacturing environments
• Expanded applications to other biotherapeutics, including fusion proteins and glycoengineered molecules

Conclusion

The ACQUITY QDa II Mass Detector delivers robust, reproducible, and sensitive glycan analysis for mAb quality control. Its extended mass range, ease of use, and Empower integration enable accurate identification and quantitation of glycans, including low-abundance impurities, supporting regulatory compliance and ensuring consistent product quality.

References

1. Luo S, Zhang B. Benchmark Glycan Profile of Therapeutic Monoclonal Antibodies Produced by Mammalian Cell Expression Systems. Pharmaceutical Research. 2024;41:29–37.
2. Lauber MA, Koza SM, Turner JE, Iraneta PC, Fountain KJ. Amide-Bonded BEH HILIC Columns for High Resolution, HPLC-Compatible Separations of N-Glycans. Waters Application Note. 2013;720004857.
3. Birdsall RE, Kellett J, Zhang X, Yu YQ. Increasing Consistency Across Biopharmaceutical Labs with the ACQUITY Premier LC Platform. Waters Application Note. 2021;720007415.
4. Goetze AM, Liu YD, Zhang Z, et al. High-mannose glycans on the Fc region of therapeutic IgG antibodies increase serum clearance in humans. Glycobiology. 2011;21(7):949–59.
5. Yu M, Brown D, Reed C, et al. Production, characterization, and pharmacokinetic properties of antibodies with N-linked mannose-5 glycans. mAbs. 2012;4(4):475–87.