Ion Chemistry in SIFT-MS

In SIFT-MS when the H30 ion is injected into the flow tube, clusters of water ions are also formed. These often react in the same way as the H3O+, ion does with the VOC providing an exoergic pathway for proton transfer exists. 

The predominant reaction of H30 reagent ions with VOCs is exothermic proton transfer 

When proton transfer is quite exothermic (more than about 1 eV), then dissociative proton transfer may occur from [AH+] as in some reactions with alcohols, aldehydes, and carboxylic acids leading to H2O eUmination [106], 

Another reaction of H3O, that does occur is association when H3O+ simply adds to the analyte molecule either as a single product or in conjunction with other product chaimels 

In some cases the weakly bound association complexes, H3O+.A, may switch out the H3O+, to water and if this happens the use of H3O as a diagnostic reagent ion is lost. 

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