Process mass spectrometry in pharmaceutical and cell culture processes

Importance of the Topic

Gas analysis mass spectrometry (MS) offers non-invasive, real-time measurement of gas and solvent concentrations in bioprocessing and pharmaceutical manufacturing. Precise monitoring of fermentation off-gas and drying headspace supports optimal culture health, process control, product quality, and regulatory compliance under the process analytical technology (PAT) framework.

Objectives and Study Overview

This study reviews two key process applications of gas analysis MS:

• Monitoring of microbial and mammalian cell fermentations via inlet and outlet gas streams
• Online tracking of solvent removal during active pharmaceutical ingredient (API) drying in vacuum, tray, or rotary dryers

The article compares magnetic sector and quadrupole MS platforms, illustrates representative data on oxygen/carbon dioxide changes and solvent profiles, and evaluates performance metrics such as precision, stability, and selectivity.

Applied Instrumentation

A magnetic sector mass spectrometer was employed for its high precision, long-term stability, and resistance to contamination. Key features include:

• Vacuum sampling pressures of 10⁻⁵ to 10⁻⁶ mbar
• Rapid cycle times (typically 5 seconds per measurement)
• Capability to analyze multiple species (e.g., N₂, O₂, Ar, CO₂, and various solvents) without frequent recalibration
• Calibration via certified gas mixtures or economical liquid standards

A quadrupole MS option is also available but the magnetic sector analyzer demonstrated superior accuracy and minimal drift over extended continuous operation.

Key Results and Discussion

In fermentation monitoring, MS data revealed consistent increases in CO₂ and decreases in O₂ between inlet and outlet streams, correlating closely with viable cell count (VCC) trends in mammalian cultures. Magnetic sector MS achieved day-to-day variation below 0.005 % mol for N₂ and O₂, and less than 1 ppm for CO₂ over a seven-day uninterrupted run.

During API drying, the MS selectively detected ethanol, methanol, tetrahydrofuran, cyclohexane, and ethyl acetate in mixed-solvent systems. One dryer containing five solvents showed distinct signals for each compound, while a second dryer with a single solvent exhibited zero cross-interference, demonstrating excellent analytical specificity.

Benefits and Practical Applications

Integration of MS into bioprocess and drying operations delivers:

• Real-time process control and early detection of contamination
• Optimized harvest and drying endpoints to maximize yield and prevent over-drying
• Reduced cycle times and improved throughput
• Lower operating costs through minimized offline sampling and laboratory analysis

Future Trends and Opportunities

Emerging developments in gas analysis MS include:

• Integration with digital twins and advanced process control systems
• Miniaturization and deployment of compact, field-portable MS units
• AI-driven data analytics for predictive process optimization
• Expanded multi-omics integration combining gas analysis with biochemical markers

Conclusion

Magnetic sector gas analysis MS represents a robust PAT tool for both fermentation monitoring and solvent drying in pharmaceutical manufacturing. Its high precision, selectivity, and long-term stability enable real-time decision making, improved product quality, and cost-effective operations. Wider adoption of this technology can drive process intensification and regulatory alignment across the industry.