Free radicals are involved in a wide variety of ageing diseases such as cancer, cardiovascular diseases and arteriosclerosis: these are known effects that have driven us to want to radically decrease the free radical contents in cigarette smoke. However the nature of free radicals in smoke is still the object of many controversies. Free radicals are usually analyzed by ESR after trapping by a spin-trap, but this lead to many pitfalls; so we decided to develop a new methodology based on mass spectrometry for the identification and quantification of free radicals.We first tested different scavengers to assess their compatibility with ESI-MS as well as their deuterated analogues. We first established the reference MS and MS/MS spectra for adducts formed with several radicals OH°, CH₃°, OCH₃°, EtS°. Actually, the free radical amount in cigarette smoke is too low and the background due to tars too important to allow for their identification using molecular peak alone. Samples must be analyzed by ESI-MS/MS and the resulting fragmentation spectrum is used to determine the nature of the free radicals in the cigarette smoke. With this methodology, we successfully identified two free radicals in the cigarette smoke, the OH° and the CH₃° radicals, and we hypothesized the presence of O₂°^- radical. Finally, when coupled to LC techniques, MS analyses allow not only for radical identification, but also for their quantification. We have applied this new method to characterize and optimize a new filter based on rosemary extracts which scavenge efficiently free-radicals in cigarette smoke¹. The relative efficiency in the removal of the various free radicals which are present in cigarette smoke (C centered, O centered) will be discussed.
¹ Iman EMAMI, Utilisation de composés polyphénoliques ou de leurs dérivés comme capteurs de radicaux libres dans les filtres de cigarette, Brevet WO9933365, 08.07.1999.