The Formation of Ions from Sample through Gas Phase Chemical Reactions

3 The Formation of Ions from Sample through Gas Phase Chemical Reactions 

Should the vapor concentration of M in the reaction region increase further, a second product ion can be formed as another sample neutral attaches to the protonated monomer, displacing a water molecule and yielding a proton-bound dimer A/2H+-(H20) r 

Protonated monomer + Sample Proton bound dimer + water 

While formation of proton-bound trimers and tetramers may occur in the vapor-rich region of the ion source, these ions have short lifetimes when extracted into the purified atmosphere of a drift region and are rarely observed in mobility spectra at ambient tanperatures or above. 

Product ions are formed in negative polarity by association of a molecule and an oxygen anion as in Equation 1.6  

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