QUADRUPOLE MASS-SPECTROMETER SYSTEM FOR FERMENTATION MONITORING

Membrane inlet mass spectrometry is used for the continuous measurement of gases and volatiles in the headspace gas of fermenters and for components dissolved in the fermentation liquid. For the monitoring of dissolved gases individual QMS units are interfaced to each fermenter in the FQ-64 system to facilitate the shortest connection pipeline to the QMS. Off-gases from 13 fermenters are sampled through a multiway-valve to another QMS. The latter unit and the dissolved gas monitors are controlled by a common computer. One unit of the FQ-64 monitoring system complete with electronics and diffusion pump is small enough to be portable (0.125 m). The mass range of the QMS is 1-64 u. A pre-filter and closed ion source increase the sensitivity and stability: less than 0.02 vol% changes of gas concentration can be measured.