Abstract: A mass spectrometer comprising an ionization means for ionizing sample compounds to be analyzed mass spectro-scopically in an atmospheric pressure, a sample solution supply means for supplying a solution containing the sample compounds to the ionization means, means for feeding the ions formed by the ionization means through an aperture disposed in an electrode into a vacuum region and a ion trap type mass spectroscopic means for mass spectroscopically analyzing ions entered through the aperture into the vacuum region, in which an ion decelerating electric field forming means is disposed between the electrode disposed with the aperture and an electrode disposed with an ion entrance opening for entering the ions into the ion trap type mass spectroscopic means for forming an electric field for decelerating the ions, and the ions injected to the ion trap mass spectroscopic means is lowered.

Abstract: A method in which cutting of small droplets, neutral particles or photons through to a slit provided between a differential pumping portion and a mass analysis portion is combined with slight deflection of ions just before introduction of the ions into the mass analysis portion so that noises are greatly reduced without reduction of signals to thereby improve the signal-to-noise ratio which is an index of detecting sensitivity or lower limit.

Abstract: A mass spectrometry apparatus which includes an ion source which ionizes a sample under atmospheric pressure and outputs the ionized sample, a differential pumping region, provided with apertures, for receiving under vacuum ions in the ionized sample from the ion source and outputting the ions and an ion accelerating and focusing region, having a plurality of ion accelerating electrodes each having applied thereto a voltage, for accelerating and focusing under vacuum the ions from the differential pumping region. The ions from the accelerating and focusing region are introduced under vacuum to a mass spectrometer which detects and analyzes the ions.

Abstract: A mass spectrometer comprising an ionization region for ionizing a sample under atmospheric pressure, an ion sampling aperture for introducing ions generated by the ionization region into a vacuum, and a mass analysis region for mass analyzing the ions on the basis of a high-frequency electric field, wherein: an electrostatic lens for deflecting the direction of the movement of the ion from the center axis of the ion sampling aperture is disposed between the ionization region and the mass analysis region; the center axis of an aperture for introducing ions into the mass analysis region and the center axis of the ion sampling aperture are disposed so as to be shifted in parallel from each other; and the center axis of the ion sampling aperture and the center axis of a cylindrical inner electrode constituting the electrostatic lens are disposed so as to be shifted in parallel from each other to thereby prevent charged droplets or droplets without charge from flowing into the mass analysis region.

Abstract: A mass spectrometer which comprises an ion source for ionizing a sample and a mass analyzing region for introducing the thus formed ions into a vacuum and mass analyzing the ions, the ion source being provided with a spray ion source comprising a heatable capillary working at least under the atmospheric pressure, the center axis of the capillary being aligned along the center of an aperture for withdrawing the ions and the tip end of the capillary being positioned close to the aperture ionizes a sample from a liquid chromatograph by both atmospheric pressure ionization mode and a thermospray ionization mode and mass analyze the ions, thereby obtaining more exact analytical information on the sample.

Abstract: An interface for liquid chromatograph/mass spectrometer (LC/MS) comprises a liquid chromatograph, an atomizing means for successively atomizing an effluent from the liquid chromatograph, and a mass spectrometer for mass-analyzing samples from the atomizing means, where the atomizing means comprises a conical horn and an ultrasonic vibrator. The conical horn has, along its center line, a perforation for passing the effluent. The ultrasonic vibrator is of a doughnut type and is provided around the conical horn and partly in close contact with the conical horn. Mists generated at the end of the conical horn are carried into the ion source of the mass spectrometer together with a carrier gas.