Interface-free two-dimensional heart-cutting capillary electrophoresis for the separation and stacking of anionic and neutral analytes

Interface-free two-dimensional heart-cutting capillary electrophoresis for two different classes of analytes (anionic and neutral) in a single capillary is presented. Simultaneous sample stacking and orthogonal separation were demonstrated. The anionic species were first analyzed by capillary zone electrophoresis in the first dimension. Then, the neutral compounds were separated in the second dimension by micellar electrokinetic chromatography using the common anionic surfactant sodium dodecyl sulfate. The first and second dimensions occurred automatically without changing the electrolyte and without polarity switching. Artificial mixtures (five anions and four neutral compounds) were successfully analyzed with sensitivity enhancement factors from 7 to 28. The orthogonal separation was complete within 8 min. Some analytical features and application to a spiked real river water sample were also studied.