ONLINE MEMBRANE INLET MASS-SPECTROMETRY FOR FEEDBACK-CONTROL OF PRECURSOR CONCENTRATION IN PENICILLIN FERMENTATION

A sampling system which enables on-line measurements of the precursor phenoxyacetic acid (POAA) in penicillin fermentation by membrane inlet mass spectrometry is presented and its capacity for feed-back regulat ion of POAA to a low predefined concentration in a penicillin-V fermen tation over 150 hours is demonstrated. The system measures alternately filtered sample and standard solution in a measuring cycle which is s horter than the response time of membrane inlet mass spectrometry (MIM S) but sufficiently long to decide whether the concentration of POAA i n the sample is higher or lower than in the standard solution at set p oint concentration. The decision is used for on-off regulation of the addition of POAA.