Determination of Fragrance Allergens by Ultraviolet Femtosecond Laser Ionization Mass Spectrometry

The allergenic compounds listed in the Cosmetics Directive by the Scientific Committee for Consumer Safety were analyzed by gas chromatography combined with multiphoton ionization mass spectrometry using a femtosecond laser emitting at 200 and 267 nm as the ionization source. The limits of detection were less than 100 pg/μL for all of the compounds, permitting them to be measured in actual samples that were simply prepared by a 100-fold dilution of the original sample. The ionization process was investigated for the 26 allergens, some of which had no absorption band, even in the far-UV region. As a result, nonresonant two-photon ionization was found to be the most sensitive and universal method for the trace analysis of these compounds, because of the short pulse width, i.e., a high peak power, of the femtosecond laser used. It should be noted that the excess energy can be reduced by using a laser emitting at longer wavelengths (267 nm) and that fragmentation can be suppressed, especially for a molecule that contains a long side chain. Three commercially available perfumes were measured, and more than 10 allergenic compounds were determined.