QUADRUPOLE MASS-SPECTROMETER SYSTEM FOR FERMENTATION MONITORING

Membrane inlet mass spectrometry is used for the continuous measuremen t of gases and volatiles in the headspace gas of fermenters and for co mponents dissolved in the fermentation liquid. For the monitoring of d issolved gases individual QMS units are interfaced to each fermenter i n the FQ-64 system to facilitate the shortest connection pipeline to t he QMS. Off-gases from 13 fermenters are sampled through a multiway-va lve to another QMS. The latter unit and the dissolved gas monitors are controlled by a common computer. One unit of the FQ-64 monitoring sys tem 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 th an 0.02 vol% changes of gas concentration can be measured.