Surface-activated-chemical-ionisation

Sensitivity 45 Sieve-based-device 39 Single-focusing mass spectrometers 49 Surface-Activated Chemical Ionisation 35... 

For the non-ideal behaviour of a system which contains a single component able to exist in different states, the rigorous thermodynamic expressions are far more complicated than those given above. The relevant mathematical formalism becomes yet more involved if the contributions of ionisation to the surface pressure of the adsorption layer and the chemical potentials of surface active ions located in the diffuse region of the double electric layer are taken into account. Therefore, to describe the adsorption behaviour of a protein/surfactant mixture, some assumptions have to be introduced which simplify the problem significantly. 

These sputtering techniques suffer from two main drawbacks, discrimination and irreproducibility. Highly surface-active species may dominate the spectra as a result of their suppression of other components of the sample at the surface of the matrix. This discrimination may result in poor sensitivity for certain species and makes quantitation difficult (see section 12.6.2). Ionisation of the matrix gives rise to chemical noise, and the spectra may be further complicated by the formation of sample-matrix adduct ions. These effects prevent the use of libraries in the interpretation of FAB and LSIMS spectra. 

An electromagnetic field at high energy ionises the air in the enviromnent and this generates chemically active species. Corona pretreatment provides a limited activation of the substrate surface to achieve an optimal bonding. 

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