Influence of the BGE composition on analyte response in CD-mediated NACE-MS

The influence of the BGE composition, including the addition of a single-isomer sulfated
beta-CD derivative, on the ionization performance of the model compound carvedilol in
NACE-ESI-MS was studied using an alternative infusion method. This approach employs
voltage-induced infusion of the BGE containing the analyte, and takes into account the
effects of variations in EOF and effective analyte mobility on the ESI-MS intensity. First,
the optimal composition of the sheath liquid for CE-MS in terms of signal abundance
and stability was determined. The BGE ammonium formate, acetate, and camphorsulfonate
were found to have similar effects on analyte ionization. Addition of single-isomer
sulfated beta-CD derivatives (available as sodium salt) to the BGE revealed that the
anionic CD derivatives did not give rise to the same ionization suppression effect. This
result can be attributed to differences in the dissociation state of these sodium salts.
Finally, it is shown that information about chiral selectivity can also be obtained with the
applied infusion method.