Département de chimie moléculaire

The internal energy of ions and the timescale play fundamental roles in mass spectrometry. The main objective of this study is to est. and compare the internal energy distributions of different ions (different nature, degree of freedom DOF and fragmentations) produced in an electrospray source (ESI) of a triple-quadrupole instrument (Quattro I Micromass). These measurements were performed using both the Survival Yield method (as proposed by De Pauw) and the MassKinetics software (kinetic model introduced by Vekey). The internal energy calibration is the preliminary step for ESI and collision-induced dissocn. (CID) spectra calcn. Meta-Methylbenzylpyridinium ion and 4 protonated peptides (YGGFL, LDIFSDF, LDIFSDFR and RLDIFSDF) were produced using an electrospray source. These ions were used as thermometer probe compds. Cone voltages (Vc) were linearly correlated with the mean internal energy values ({\textless} Eint {\textgreater}) carried by desolvated ions. These mean internal energy values seem to be slightly dependent on the size of the studied ion. ESI mass spectra and CID spectra were then simulated using the MassKinetics software to propose an empirical equation for the mean internal energy ({\textless} Eint {\textgreater}) vs. cone voltage (Vc) for different source temps. (T): {\textless} Eint {\textgreater} = [405 × 10-6 - 480 × 10-9 (DOF)] VcT + Etherm(T). In this equation, the Etherm(T) parameter is the mean internal energy due to the source temp. at 0 Vc. [on SciFinder(R)]