A Rapid and Reproducible Immuno-MS Platform from Sample Collection to Quantitation of IgG

Importance of the Topic

Quantitative analysis of Immunoglobulin G (IgG) in biological samples is critical for clinical diagnostics, therapeutic monitoring, and immunological research.
The development of a rapid, sensitive, and reproducible Immuno-MS workflow addresses challenges in sample stability, hematocrit variability, and throughput, enabling reliable IgG measurements from minimally invasive dried plasma spots.

Objectives and Study Overview

This work aimed to integrate next-generation plasma separator cards with automated immunoaffinity enrichment and high-speed LC-MS/MS to establish a streamlined platform for IgG quantitation.
Key objectives included:

• Evaluating the speed and reproducibility of sample processing from whole blood to peptide measurement.
• Assessing calibration linearity, accuracy, and carryover.
• Demonstrating applicability for routine clinical or research workflows.

Methodology and Instrumentation

Whole blood samples spiked with defined IgG standards were applied to Noviplex™ cards to generate dried plasma spots (DPS). The workflow consisted of:

• Rapid plasma extraction (≈18 min total): 2.5 µL plasma collection, 15 min air-drying, disc excision, and solvent extraction.
• Automated immunoaffinity selection of IgG via Protein G on the Perfinity workstation.
• On-line trypsin digestion (1–8 min) and desalting, followed by ultra-fast reversed-phase LC.
• MRM-based detection on the LCMS-8050 triple quadrupole MS with heated electrospray, polarity switching (5 ms), and scan speeds up to 30 000 u/sec.

Main Results and Discussion

The platform delivered:

• High reproducibility (CV < 10%) for retention time and peak area across multiple replicates.
• Linear calibration curves over 22.5–465 µg/mL with r² > 0.97 for signature IgG peptides TTPPVLDSDGSFFLYSK and VVSVLTVLHQDWLNGK.
• Accuracy in QC samples between 87% and 117% across concentration levels.
• Negligible carryover in blank injections following high-level standards.

Chromatographic profiles and optimized collision energies ensured robust peptide detection within a total run time under 10 minutes.

Benefits and Practical Applications

This Immuno-MS platform offers:

• Minimal sample volume requirement (≈50 µL whole blood).
• Fully automated workflow reducing hands-on time and variability.
• Rapid throughput suited for high-volume clinical or research laboratories.
• Scalability to other protein/peptide targets via affinity selection.

It supports applications in therapeutic antibody monitoring, immunodeficiency screening, and biomarker quantitation.

Future Trends and Potential Applications

Emerging directions include:

• Expansion to multiplexed protein panels for broader immunophenotyping.
• Integration with advanced data analysis software (e.g., Skyline/LabSolutions) for automated reporting.
• Adoption of ambient sampling and microfluidic interfaces to further reduce sample preparation time.
• Application to other biofluids and dried matrix formats for decentralized testing.

Conclusion

The combination of Noviplex plasma cards, Perfinity immunoaffinity robotics, and the LCMS-8050 instrument establishes a fast, reproducible Immuno-MS platform for IgG quantitation.
Its performance meets rigorous accuracy and precision criteria, making it a promising solution for clinical and industrial analytics.

References

• Lieberman R., Colquhoun D., Post J., et al. A Rapid and Reproducible Immuno-MS Platform from Sample Collection to Quantitation of IgG. ASMS 2014 ThP766.