Electrospray mass spectrum infused

Figure 4. Electrospray mass spectrum of infused pigmented tannin. (Reproducedfrom reference 16, with permission from the Australian Society of Viticulture and Oenology)...

FIGURE 47.5 Representative mass spectrum of leucine-enkephalin obtained using chip with open channel emitter (a) and porous polymer monolith-assisted electrospray process from a microdevice at a constant infusion (b). (Reprinted with permission from Koerner, T. and Oleschuk, R. D Rapid Comm. Mass Spectr., 19, 3279, 2005. Copyright 2005 J. Wiley.) Conditions peptide solution 1.0 p-mol/L in 50% aqueous acetonitrile with 0.5% acetic acid, flow rate of 100 nL/min, applied voltage of 3.5 and 3.0 kV, respectively. 

To summarise, a fractionation step allows the isolation of the compounds of interest from the other molecular constituents, particularly from the fatty acids that are well-ionised. To compensate for the low ionisation yield of some compounds, such as TAGs, the solutions may be doped with a cation. Samples are then directly infused into the ion electrospray source of the mass spectrometer. A first spectrum provides an overview of the main molecular compounds present in the solution based on the peaks related to molecular cations. The MS/MS experiment is then performed to elucidate the structure of each high molecular compound. Table 4.2 shows the different methods of sample preparation and analysis of nonvolatile compounds as esters and TAGs from reference beeswax, animal fats and archaeological samples. 

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