ATMOSPHERIC PRESSURE IONIZATION MASS SPECTROGRAPH

PURPOSE:To enable highly sensitive measurement with easier setting of a probe to a maximum sensitivity point by arranging a tip of a probe for atomizing a sample or a mobile phase to be movable horizontally, vertically and longitudinally with respect to an ion sampling fine hole. CONSTITUTION:A sample injected into a liquid chromatography LC reaches an electrospray ion (ESI) probe 3 passing through a sample pipe 2 to be ionized and a peak intensity thereof increases gradually. At this point, a knob of a holder 10 is lifted to turn the holder 10 so that the tip of the probe 3 is decentered from the center axis of an ion sampling fine hole 6 vertically or horizontally and moreover, the tip is moved longitudinally with respect to the fine hole 6 to be set to a point at which a liquid drop flying from the tip of the probe 3 causes an ion evaporation most efficiently, namely, a highest sensitivity position. Here, the tip can be set to the highest sensitivity point checking the application of a high voltage the probe 3 being insulated, namely the peak intensity of the actual sample or the peak intensity of a background with a monitor thereby facilitating the setting.