Real-time update of calibration model for better monitoring of batch processes using spectroscopy.
In order to reduce the large calibration matrix usually required for calibrating multiwavelength optical sensors, a simple algorithm based on the addition in process of new standards is proposed. A small calibration model, based on 14 standards, is periodically updated by spectra collected on-line during fermentation operation. Concentrations related to these spectra are reconciled into best-estimated values, by considering carbon and oxygen balances. Using this method, fructose, acetate, and gluconacetan were monitored during batch fermentations of Gluconacetobacter xylinus 12281 using mid-infrared spectroscopy. It is shown that this algorithm compensates for noncalibrated events such as production or consumption of by-products. The standard error of prediction (SEP) values were 0.99, 0.10, and 0.90 g/L for fructose, acetate, and gluconacetan, respectively. By contrast, without an updating of the calibration model, the SEP values were 2.46, 0.92, and 1.04 g/L for fructose, acetate, and gluconacetan, respectively. Using only 14 standards, it was therefore possible to approach the performance of an 88-standard-based calibration model having SEP values of 1.11, 0.37, and 0.79 g/L for fructose, acetate, and gluconacetan, respectively. Therefore, the proposed algorithm is a valuable approach to reduce the calibration time of multiwavelength optical sensors.
Kornmann
Henri
H
Laboratory of Chemical and Biochemical Engineering, Swiss Federal Institute of Technology (EPFL), CH-1015 Lausanne, Switzerland.
Valentinotti
Sergio
S
Marison
Ian
I
von Stockar
Urs
U
D000085:Acetates / Q000032:analysis; D000465:Algorithms; D019149:Bioreactors; D002138:Calibration; D018929:Cell Culture Techniques; D003470:Culture Media; D005285:Fermentation; D005632:Fructose / Q000032:analysis; D041822:Gluconacetobacter xylinus / Q000254:growth & development / Q000378:metabolism*; D008954:Models, Biological; D009862:Online Systems; D013055:Spectrophotometry, Infrared / Q000295:instrumentation / Q000379:methods*; D013997:Time Factors
D000085:Acetates; D003470:Culture Media; D005632:Fructose