In-source dissociation

Yan Z, Caldwell GC, Jones WJ, Masucci JA (2006) Cone voltage induced in-source dissociation of glucuronides in electrospray and implications in biological analyses. Rapid Commun Mass Spectrom 17 1433-1442... 

K. Sannes-Lowery, R.H. Griffey, G.H. Krappa, J.P. Spier, S.A. T ofA.aA e.r, Multipole storage assisted dissociation, a novel in-source dissociation technique for ESI generated ions. Rapid Commun. Mass Spectrom., 12 (1998) 1957. 

Note In particular the MALDI-TOF community has coined some sort of an own terminology, e.g., in-source decay (ISD) for all fragmentations occurring within the ion source, post-source decay (PSD) instead of metastable ion dissociation and fragment analysis and structural TOF (FAST) for the specific mode of operation of a ReTOF to detect metastable ions. 

Similar analysis strategies are applied for the peptide mapping of glycoproteins (Medzihradszky et al., 1994 Reinhold et al., 1995 Hancock et al., 1996). Carr and co-workers combined in-source col-lisionally induced dissociation (CID) with LC/MS/MS to identify sites of N- and O-linked glycosylation (Carr et al., 1993). This novel approach uses a series of LC/MS and LC/MS/MS experiments to generate peptide maps and to selectively screen for glycoproteins. 

Examples of the latter two sources of the channel phase are illustrated in Fig. 11. From an independent knowledge that the channel phase for ionization of H2S is zero (or 7i), it is deduced that the phase lags A8(I, H2S+) and A8(HI+, H2S+) are equal, respectively, to the channel phases (modulo tv) for the dissociation (< [3) and ionization (< /+) of HI. The nearly flat, nonzero values of 8[3 (triangles in Fig. 11a) is indicative of coupling in the dissociation continuum, whereas the peak in 8(diamonds)... 

According to the Arrhenius theory, acids increase the concentration of H+ in aqueous solutions. Thus, an Arrhenius acid must contain hydrogen as the source of H+. You can see this in the dissociation reactions for acids on the previous page. 

The on-line coupling of CE with electrospray ionization mass spectrometry (CE-ESI-MS) allows high separation efficiency together with high sensitivity and selectivity as well as molecular structural information. A CE-UV-ESI-MS method was developed for the analysis of hoscyamine, scopolamine, and other tropane derivatives [131]. The differentiation of hyoscyamine from littorine, commonly encountered in plant material, was demonstrated using in-source collision-induced dissociation. The developed method was applied to the analysis of these alkaloids in Belladonna leaf extract and in Datura Candida x D. awreahairy root extract. Recently, CE coupled with electrochemiluminescence detection has been used for the determination of atropine and scopolamine in Flos daturae [132]. 

Two mechanisms can be distinguished depending on whether the compound is chemisorbed in a dissociative [Eqs. (20) and (21)] or associative [Eqs. (22) and (23)] manner. If heavy water is used as source of isotope, it supplies deuterium to the catalyst surface through dissociative adsorption [Eq. (24)]. 

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