Ionization Method for Weakly Polar Molecules Using Ion Association Reaction in Nonpolar Solvent

Ionization methods for mass spectroscopy have been developed, and selected depending on the analyte species or experiment conditions. There still remains a problem for detecting some weakly polar molecules using the conventional methods. We developed a novel method to enable us to ionize a lot of weakly polar molecules softly. This method has two important features using a nonpolar solvent and a cationization reagent. First, cations of the cationization reagents are such strong Lewis acid that they attach to weakly polar molecules in nonpolar solvents. Second, the cations associated with the analyte molecules form stable ion pairs with the counter ions. In this paper, we demonstrate the utility of this method for some of weakly polar molecules by using cation(Li,Ag)-tetrakis[3,5-bis(trifluoromethyl-phenyl]borate [Cation (Li,Ag)-TFPB].