Effect of high pH mobile phase on the sensitivity of multiple drugs by LC positive electrospray ionization MS/MS

In this study, the postcolumn addition approach was used to evaluate the impact of high pH modifiers on the sensitivity of 25 compounds by LC-MS/MS under positive ESI (ESI+).

None of the compounds were significantly suppressed by the use of high pH modifiers. Most of them showed a signal enhancement by at least twofold compared with acidic modifiers. The sensitivity gained under high pH mobile phase was used to develop a bioassay for the quantification of candesartan. The use of high pH mobile phase allowed for fast sample preparation that would have been impossible under typical low pH chromatography.

We have shown that high pH modifiers are sufficient to induce a signal enhancement for the majority of compounds detected under LC-ESI+-MS/MS.