Protonation of Caff eine; Theoretical and Experimental Study

Caffeine or trimethylxanth ine is a cen tral nervou s system and metabolic stimulant [۱]which i s widely c onsumed as tea, coffee and additive in drinks. The d etection an dmeasure ment of ca ffeine have attracted the interest of num erous researchers. Mass spectrom etric analysis of caffein e with coro na discharge ionization source showed only o ne major pe ak at m/z ۱۹۵ corresp onding to M H+ ion [۲]. However, our experim ental studies using an ion mobilit y spectrometer (IMS) with corona discharge as ionization source showe d that the caffeine spectrum included two dis tinct produ ct ion peaks. Here, we report a joint theoretical and experimental in vestigation of caffeine related ions. Consideri ng theoretical calculati on and experimental evidences we conclude that there is more tha n one stable protonat ed caffeine which are not distinguis hable in mass spectrometer, but sepa rated in IM S.

کلیدواژه ها:

thermodynamic ، calc ulation ، proton affinity ، ion mobility spectrometry ،