Abstract: The present invention aims to provide a liquid chromatograph, an analysis system, and a gradient elution method, which are designed to permit a gradient change of eluent with higher precision and also permit a high sensitive detection or analysis.

Abstract: A problem is to provide a microspray column capable of increasing the ionization efficiency, and a high sensitive mass spectrometer and a mass spectrometric method using such a microspray column. For solving this problem, we provide a column for introducing a sample in an ionization source of a mass spectrometer (ESI/MS) being designed to ionize a sample molecule with electrospray and introduce it into an analyzer, has structural features of: (1) 0.5 ?m or less in an inner diameter of a tip opening of the column; (2) 0.5 ?m or more and 5 ?m or less in a particle size of a column filler; and (3) fritless, a microspray column having the above (1) to (3), a mass spectrometer having such a microspray column in an ionization source, and a mass spectrometric method capable of performing a nonoflow electrospray with the microspray column.