General approach for the analysis of various alkaloid classes using capillary electrophoresis and capillary electrophoresis mass spectrometry

The analysis of various alkaloid classes employing capillary electrophoresis (CE) and on-line combined CE-mass spectrometry (CE-MS) is described. A CE method is presented for the analysis of alkaloids without derivatisation or purification. The separation of four different groups of alkaloids consisting of monoterpenoid indole alkaloids, protoberberines/benzophenanthridines, beta-carboline alkaloids, and isoquinolines from poppy by free zone capillary electrophoresis has been obtained using a 1:1 mixture of 100 mmol l(-1) ammonium acetate (pH 3.1) and acetonitrile. The influence of alkaloid structure on the electrophoretic mobility is discussed. The CE-MS reconstructed total ion current (RIC) of the indole- and the opium-type standard alkaloids shows a decreased signal-to-noise ratio compared to CE using only UV detection. As expected the single-ion traces (or individual mass traces) of the [M+H](+) ions show higher signal-to-noise ratios than the RIC. The electrospray MS data of the alkaloids are dominated by the protonated molecules and the Na+-, and K+-adducts. They display the typical pattern resulting from cluster formation or doubly charged species.