DIRECT ANALYSIS OF ODORS EMITTED BY FRESHLY CUT ALLIUM USING COMBINEDHIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY AND MASS-SPECTROMETRY

Allium odors were re-examined to determine whether or not they contain degradation compounds of thiosulfinates. Garlic (Allium sativum), lee k (Allium porrum) and onion (Allium cepa) were investigated using cryo trapping and direct injection of aqueous solutions of the samples into a high-performance liquid chromatograph (HPLC), with a diode-array de tector, coupled to a mass spectrometer (MS). Various commercial system s which couple HPLC to tandem MS, but using different ionization syste ms, were compared, Best results were obtained with atmospheric pressur e chemical ionization although degradation of certain thiosulfinates w as observed. Depending on the HPLC/MS interface, thiosulfinates formed dimers in variable quantity and this reaction could be used to differ entiate isomeric 1-propenyl and 2-propenyl thiosulfinates. Some unreso lved isomers were identified by their fragment ions. No disulfides or other rearrangement products were observed and it was concluded that A llium odors contain only thiopropanal S-oxide and thiosulfinates as su lfur volatiles.