Schematic representation of the GC/DMS instrument setup. The volatile compounds collected from headspace of EBC are introduced into gas chromatograph (GC) column for chromatographic separation. The sample eluting from GC column is ionized with 63Ni ion source prior to entering the DMS sensor. The filtered ions are detected at their corresponding compensation voltage values. El:, low-field electric field strength, tl: duration of the low-field portion of the waveform ; Eh:, high-field electric field strength; th: duration of the high-field portion of the waveform Rf, radiofrequency waveform; Vc, compensation voltage