Reversed-phase high-performance liquid chromatography-electrospray mass spectrometry profiling of transgenic and non-transgenic maize for cultivar characterization.

A reversed-phase high-performance liquid chromatography-electrospray mass spectrometry (RP-HPLC-ESI-MS (ion trap)) method is developed, for the first time, for profiling transgenic and non-transgenic maize with the aim of cultivar characterization. To optimize chromatographic conditions the following parameters were studied: column, gradient, and ion-pairing reagent. Moreover, the influence in the MS signal of the variation of the capillary voltage and the accumulated ions in the trap was also studied. The developed method was applied to the profiling of different protein fractions (albumin, globulin, prolamin, and glutelin) isolated from Bt transgenic and non-transgenic maize cultivars. Moreover, different maize samples, namely, maize cultivars from different geographical origins (USA, Canada, France, and Spain), transgenic maize samples with certified GMO content, and three transgenic Bt maize cultivars with their isogenic non-transgenic counterparts (Aristis Bt vs. Aristis, PR33P67 vs. PR33P66, and DKC6575 vs. Tietar) were profiled by the developed method. Mass spectra obtained for certain peaks in the maize cultivars studied resulted, in some occasions, useful for cultivar characterization and differentiation. The comparison of UV and MS profiles and mass spectra corresponding to the protein fractions with those of the whole seeds enabled the assignment of some peaks.