Fig. 4.

Total ion chromatograms of bacterial headspace samples. For pre-concentration, VOCs of 2 L headspace volume have been adsorbed to Tenax GR. Total ion chromatograms are shown from 7 to 28 min. Identity of VOCs is summarized in Table 2. Cyclohexanol Rt = 12.17 min, styrene Rt = 12.35 min, cyclohexanone Rt = 12.45 min, benzaldehyde Rt = 14.14 min, 2-ethyl-1-hexanol Rt = 15.61 min and acetophenone Rt = 16.68 min have been detected as main volatile compounds over Columbia sheep blood agar. Benzothiazole—a contaminant of the operation gas—has been detected in every headspace sample at Rt = 20.37 min