Process analysis of the acetone-butanol fermentation by quadrupole mass spectrometry

Mass spectrometry: a tool for on-line monitoring of animal cell cultures

The magnetic sector mass spectrometer is able to detect oxygen uptake and carbon dioxide production rates from animal cell cultivations performed in 101 bioreactors. Such data have not been available with the use of classic exhaust gas analysis applying paramagnetic analyzers and infra-red sensors due to the insensitivity of the apparatus available. In the course of the present work we were able to demonstrate, that the oxygen uptake rate correlates to the number of viable cells. Additionally oxygen uptake rates supplied on-line information about the actual physiology of the cells: When the rates changed during the cultivation process, this immediately indicated the occurrence of limitations of components in the medium. The information could be useful in timing key events, such as performing splits or harvesting the bioreactor.

Present and potential applications of mass spectrometry for bioprocess research and control

For on-line monitoring of bioprocesses present applications are mainly restricted to gas analysis, but several techniques have been improved recently: membrane probes, the application of MS/MS techniques, methods of correlating available on-line data like gas reaction rates with bioprocess characteristics using stoichiometric models and other empirical correlations. New ionization and ion separation methods for biomolecules are developing dramatically. Most striking developments in this area are improved desorption techniques, electrospray, the renaissance of time-of-flight instruments and new challenges in ion trap techniques. Enormous progress is made in the analysis of peptides and other biopolymers. Combinations with new separation techniques like capillary electrophoresis and capillary HPLC show new horizons in biomolecule analysis.

Process dynamics, instrumentation and control

A total of 77 references pertaining to the subject were consulted to compose the present review. In addition to their years of publication (1981-1983), the references were selected primarily for their practicality and ability to provide experimental results and confirmation. First, a generalized model illustrating the biochemical reaction engineering considerations is presented. Here the knowledge of reactor and reaction kinetics is emphasized and the need for process instrumentation identified. Recent developments in key process sensors are then discussed in detail along with their utilities in various process situations. Finally, application of control principles and on-line computers to biochemical process operation is given a realistic evaluation by considering the process dynamics and instrumentation capabilities. Future challenges and opportunities from both the reaction engineering and system engineering points of view are carefully assessed. The most recent review relevant to the subject is that by Bull (1983).