Analyses of gibberellins by capillary electrophoresis–mass spectrometry combined with solid-phase extraction

A new, simple and rapid capillary electrophoresis–mass spectrometry (CE–MS) method, using a cationic polymer-coated capillary to reverse electroosmotic flow, is proposed and validated for the separation and simultaneous quantification of 11 gibberellins (GAs). Under optimum conditions, a baseline separation of 11 GAs, including GA1, GA3, GA4, GA5, GA6, GA7, GA13, GA19, GA20, GA24 and GA53 was accomplished within 25 min using 70 mM ammonium formate/formic acid buffer (pH 3.8) and 2% (v/v) acetonitrile with −25 kV as the separation voltage. Satisfactory results were obtained in terms of linearity (R2 between 0.984 and 0.995), precision (RSD of migration time below 0.8%) and sensitivity (LOD between 0.31 and 1.02 μM). Furthermore, a novel solid-phase extraction (SPE) procedure was developed for the pre-concentration and purification of GAs using Oasis MAX cartridges. The combination of SPE and CE–MS approach was applied to screen for endogenous GAs present in coconut (Cocos nucifera L.) water sample. To illustrate the applicability of the method, GA1 and GA3 were successfully detected and quantified in coconut water. Finally, the GA1 and GA3 identities were further unequivocally confirmed by CE-tandem MS experiments operating in the multiple reaction monitoring mode.