HIGH-FLOW LIQUID-CHROMATOGRAPHY MASS-SPECTROMETRY INTERFACE USING A PARALLEL ION-SPRAY

By positioning the capillary of the ion spray parallel to the ion sampling orifice, several advantages have been found compared to the conventional perpendicular ion spray, e.g., higher sensitivity, stable operation, practically no contamination of the ion sampling orifice, and higher liquid Bow rates up to 4 mL/min. This is due to the fact that while the charged fine liquid droplets are deflected towards the ion sampling orifice, the larger liquid droplets with lower charge density are entrained in the nebulizer gas jet and they are carried away outside the ion sampling system. With higher liquid flow rates (e.g. greater than or equal to 500 mu L/min), the start of corona discharge does not result in a drastic decrease in the signal intensities of ions originating from sample solution. In electrospray experiments, it has also been found that the parallel spray gives better performance than the perpendicular one.