SIMULTANEOUS MEASUREMENT OF GLUCOSE AND GLUTAMINE IN INSECT-CELL CULTURE MEDIA BY NEAR-INFRARED SPECTROSCOPY

The purpose of this study was to develop noninvasive techniques to mon itor the composition of cell culture media in insect cell bioreactors. Such a monitor could be used in conjunction with a fed-batch feeding scheme to ensure that cells are maintained in an optimal environment f or growth and protein production. Glucose and glutamine concentrations in an insect cell culture bioreactor were determined off-line with ne ar-infrared (NIR) absorption spectroscopy. Spectra were collected from 5000 to 4000 cm(-1) with a 1.5-mm optical path length. Partial least squares (PLS) regression was applied to correlate the collected spectr a with the concentration of the desired analytes. Under the culture co nditions evaluated here, glucose and glutamine concentrations ranged f rom 38 to 55 mM and from 3 to 13 mM, respectively. Accurate measuremen ts of glucose and glutamine in insect cell culture samples were possib le over these entire ranges. The standard error of prediction (SEP) an d mean percent error (MPE) for glutamine were 0.52 mM and 5.3%, respec tively. Glucose could be measured with an SEP of 1.30 mM and an MPE of 2.3%. These levels of error are quite low considering the changing co mplexity of the growth media due to the shifting levels of amino acids , carbohydrates, yeastolate, proteins, and cell debris. This study rep resents an important step in the development of noninvasive on-line mo nitoring devices for cell culture bioreactors. (C) 1997 John Wiley & S ons, Inc.