Electrospray Emitters In Amster lab, we are often given samples that are only 10 uL and have nanograms of samples, so we manufacture our own borosilicate glass nanoESI emitters that allow us to spray these small samples into a mass spectrometer for up to an hour. These emitters typically have an inner diameter at the tip of about 1 um. Capillaries for Capillary Zone Electrophoresis Many of our projects involve the use of Capillary Zone Electrophoresis coupled to Mass Spectrometry (CZE-MS). We customize our capillaries with covalent modifications which help increase performance in negative polarity CZE separations. and can make dimethylsilane (DMS), aminomethyltriethoxysilane (AHS) and linear poly-acrylamide (LPA) coatings. Pictured below (left) is a fused silica capillary that has been etched from an initial outer diameter of 360 um to a diameter of 60 um. In order to interface CZE with a mass spectrometer, we use an electrokinetically pumped sheath flow interface (DOI). This requires us to etch the tip of the separation capillary to a smaller diameter to fit inside a glass electrospray emitter and minimize the mixing volume to enhance signal to noise. Pictured below (left) is a CZE-MS sheath flow interface consisting of a glass CE emitter with an etched fused silica capillary inserted inside. Pictured on the right is a diagram of the same interface. The Sheath liquid is shown in blue and the capillary buffer liquid is shown in blue. As analytes elute from the end of the capillary, they are mixed with the solvent in the CE emitter and sprayed into the mass spectrometer.
