Abstract: [Problem] To provide a mass spectrometry method that uses a chromatography-mass spectrometry device, wherein mass spectrometry can be performed with a convenient method at low cost. [Solution] A mass spectrometry method for a target object, using a chromatography-mass spectrometry device that includes, in order, a chromatograph, an ionization unit, a first mass separation unit, a collision cell, a second mass separation unit, and an ion detection unit, wherein an ion pair agent and Hünig's base are added to a mobile phase of the chromatograph, and the absolute value of an applied voltage of the collision cell is 20V to 250V.

Abstract: A liquid chromatograph mass spectrometer includes a liquid chromatograph unit for performing liquid chromatography, an atomizer having a controllable temperature for heating and atomizing a liquid flowing out of the liquid chromatograph unit during liquid chromatography to produce an atomized liquid, an ionizing device for ionizing the atomized liquid to produce an ionizing sample, a mass spectrometer for analyzing the ionized sample, a storage device for successively storing liquid chromatography conditions and respective atomizer temperatures used for the liquid chromatography conditions for past measurements performed with the liquid chromatograph mass spectrometer, an input device for inputting a current liquid chromatography condition for a current measurement, a retrieving device for retrieving from the storage device a liquid chromatography condition nearest to the current liquid chromatography condition among the liquid chromatography conditions stored in the storage device, and the atomizer temperatu