Expert View: Beyond API monitoring: in‑line Raman spectroscopy for bioprocess monitoring and control

Posted: 19 December 2018 | | No comments yet

The FDA’s Quality by Design (QbD) initiative brought a paradigm shift to pharmaceutical manufacturing and leading manufacturers have realised improved processes after adopting QbD. Raman spectroscopy is an established Process Analytical Technology (PAT), enabling QbD and continuous approaches to pharmaceutical manufacturing.1

Raman spectroscopy is used for a variety of active pharmaceutical ingredient (API) applications, including polymorph identification, quantitative analysis, in situ crystallisation monitoring, real-time release testing, unit operations monitoring, process‑induced transformations and continuous tableting.2-6 The diverse API structures and formulations that have been quantified by Raman show that Raman methods can reliably provide quantitative data. The successes of in-line Raman spectroscopy in API crystallisation and drug product formulation establishes an application basis for in situ bioprocess monitoring.

QbD and PAT initiatives support bioprocessing and emphasise the importance of real-time analysis in biopharmaceutical manufacturing. The extension of Raman spectroscopy to bioprocessing has been successfully demonstrated for upstream and downstream applications.7 Similar to API applications, Kaiser’s in-line Raman analysers for bioprocessing provide chemically-specific data, demonstrate excellent model transferability8 and can be performed continuously and directly in the bioreactor. Raman has been successfully applied to biopharmaceutical development in industrial settings, from process development to GMP manufacturing. Customers have reported benefits of in situ Raman for both cell culture and fermentation bioprocesses. Application benefits of Raman in upstream biopharmaceutical manufacturing include the ability to simultaneously measure nutrients, metabolites and cell viability, cross-scale method transfer without significant method rework, and the ability to implement advanced process control.7-10 Bioprocess‑optimised in situ Raman probes enable CIP/SIP and are compatible with glass, stainless steel and single-use bioreactors. Recent studies demonstrate that Raman‑based feedback control of glucose or lactate in cell cultures enables longer culture duration, improves monoclonal antibody (mAb) quality and improves titre up to 85 percent.11-13 Advanced process control and adaptive feeding are possible even in highly fluorescing bioprocesses, with the use of 993nm excitation Raman systems.14

In a representative example, Berry et al reported that a Raman-based feedback control system was highly successful in minimising glycation of the mAb product, lowering the glycation from 9 to 4 percent relative to a traditional bolus feed.12 Raman‑based glucose control was achieved after only two calibration steps and eight concurrent bioreactor runs. The analytical model was quickly integrated into process development work and shown to successfully control a protein product attribute. Raman supported a targeted concentration condition or a stepwise condition, demonstrating Raman as a robust method to integrate into a controller of an industrially-relevant bioprocess. Since the Raman-based feed control was introduced early in process development, unintended process changes could be identified and quickly corrected before the process was scaled to manufacturing. One example of a process change was that the replacement rate for the complex nutrient feed was moved to four days in order to avoid precipitation.



Raman is a proven PAT for small molecule manufacturing and bioprocessing. Kaiser has been a leader of in situ monitoring and control in bioprocessing since 2007 because of our robust in situ Raman solutions and expertise in life sciences from R&D to GMP.



  1. Esmonde-White K, Cuellar M, Uerpmann C, Lenain B, Lewis I. Raman spectroscopy as a process analytical technology for pharmaceutical manufacturing and bioprocessing. Anal. Bioanal. Chem. 2016; 409: 637–649
  2. Hédoux A, Guinet Y, Descamps M. The contribution of Raman spectroscopy to the analysis of phase transformations in pharmaceutical compounds. Int. J. Pharm. 2011; 417: 17–31
  3. DeBeer T, et al. Near infrared and Raman spectroscopy for the in-process monitoring of pharmaceutical production processes. Int. J. Pharm. 2011; 417: 32–47
  4. Knop K, Kleinebudde P. PAT-tools for process control in pharmaceutical film coating applications. Int. J. Pharm. 2013; 457: 527–536
  5. Müller J, Knop K, Wirges M, Kleinebudde P. Validation of Raman spectroscopic procedures in agreement with ICH guideline Q2 with considering the transfer to real time monitoring of an active coating process. J. Pharm. Biomed. Anal. 2010; 53: 884–894
  6. Nagy B, et al. In-line Raman spectroscopic monitoring and feedback control of a continuous twin-screw pharmaceutical powder blending and tableting process. Int. J. Pharm. 2017: 530; 21–29
  7. Abu-Absi N, et al. Real time monitoring of multiple parameters in mammalian cell culture bioreactors using an in-line Raman spectroscopy probe. Biotechnol. Bioeng. 2011: 108; 1215–1221
  8. Berry B, Moretto J, Matthews T, Smelko J, Wiltberger K. Cross-scale predictive modeling of CHO cell culture growth and metabolites using Raman spectroscopy and multivariate analysis. Biotechnol. Prog. 2015: 31; 566–577
  9. Mehdizadeh H, et al. Generic Raman-based calibration models enabling real-time monitoring of cell culture bioreactors. Biotechnol. Prog. 2015: 31; 1004–1013
  10. Whelan J, Craven S, Glennon B. In situ Raman spectroscopy for simultaneous monitoring of multiple process parameters in mammalian cell culture bioreactors. Biotechnol. Prog. 2012: 28; 1355–1362
  11. Craven S, Whelan J, Glennon B. Glucose concentration control of a fed-batch mammalian cell bioprocess using a nonlinear model predictive controller. J. Process Control 2014: 24; 344–357
  12. Berry B, et al. Quick generation of Raman spectroscopy based in-process glucose control to influence biopharmaceutical protein product quality during mammalian cell culture. Biotechnol. Prog. 2016: 32; 224–234
  13. Matthews T, et al. Closed loop control of lactate concentration in mammalian cell culture by Raman spectroscopy leads to improved cell density, viability and biopharmaceutical protein production. Biotechnol. Bioeng. 2016: 113; 2416–2424
  14. Matthews T, et al. Glucose Monitoring and Adaptive Feeding of Mammalian Cell Culture in the Presence of Strong Autofluorescence by near Infrared Raman Spectroscopy. Biotechnol. Prog. 2018 doi:10.1002/btpr.2711