Few studies have reported effective means to increase ESI-charging beyond that measured under normal experimental conditions. Increasing the charge carried by analytes is desirable, because higher charged molecules are more effectively dissociated by tandem MS and because they reduce analyzer m/z requirements. Recently, we demonstrated that multiple charging of native proteins and noncovalent protein complexes could be increased in ESI-MS when spectra are obtained from no denaturing protein solutions containing up to 1percent (v/v) mnitrobenzyl alcohol (m-NBA). (Lomeli et al, JASMS 2009) Charge increased by +8percent to +48percent for the native proteins measured. Now we present other compounds as potent as m-NBA for supercharging under both native and denaturing conditions, and discuss possible physical and chemical properties impacting multiple charging behavior.
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