A microfabricated micropillar liquid chromatographic chip monolithically integrated with an electrospray ionization tip

We present the first monolithically integrated silicon/glass liquid chromatography-electrospray ionization microchip for mass spectrometry. The microchip is fabricated by bonding a silicon wafer, which has deep reactive ion etched micropillar-filled channels, together with a glass lid. Both the silicon channel and the glass lid have a through-wafer etched sharp tip that produces a stable electrospray. The microchip is also compatible with laser induced fluorescence (LIF) detection, due to the glass lid. Separation of drugs in less than 5 minutes using either SiO2 (normal phase) or C-18 coated (reversedphase) pillars with good sensitivity was demonstrated with mass spectrometric detection as well as separation of fluorescent compounds with LIF detection.