Apparatus for mass spectrometry on an ion-trap method

An ion trap type mass spectrometer comprising:

• a ring electrode;
• a pair of end cap electrodes arranged facing one another so as to arrange said ring electrode between said end cap electrodes,
• a radio-frequency power supply for applying to said ring electrode and said end cap electrodes a radio-frequency voltage that generates a radio-frequency electric field in the space formed between said ring electrode and said end cap electrodes,
• an ion generator for creating ions inside said inter-electrode space or creating ions outside said space and introducing the ions thereinto,
• a trapper for trapping created ions in said inter-electrode space where said radio frequency electric field is formed,
• an alternating-current (AC) electric field generator for generating in said space wideband auxiliary AC electric fields which comprise plural different frequency components, the frequency range of which are corresponding to the mass-to-change ratio range of undesired ions to eject the undesired ions by resonant ejection;
• and
• a detector for sequentially separating the ions trapped in said space in terms of mass according to the particular mass-to-charge ratio of the ion and detecting the mass of these ions after the trapped ions have been emitted from said space;
• an electric field changer for varying the strength of wideband auxiliary AC electric fields comprising the frequency components within the required frequency range according to the strength of the radio-frequency electric field generated in said space;
• wherein said electric field varies said wideband auxiliary AC voltages according to the strength level of the radio-frequency electric field generated in said inter-electrode space;
• wherein said electric field varies the amplitude values of individual auxiliary AC voltages of the different frequencies within the required frequency range according to the particular frequencies of each frequency component at said wideband auxiliary AC voltages;
• and
• wherein the amplitude values of the auxiliary AC voltages of frequency components having frequencies near the ends of the required frequency range of said auxiliary AC voltages are set to be equal to, or less than, the amplitudes of said auxiliary AC voltages of frequency components having the frequencies corresponding to the median region of the required frequency range.

An ion trap mass spectrometer comprising:

• a ring electrode;
• a pair of end cap electrodes arranged facing one another so as to arrange said ring electrode between said end cap electrodes,
• a radio-frequency power supply for applying to said ring electrode and said end cap electrodes a radio-frequency voltage that generates a radio-frequency electric field in the space formed between said ring electrode and end cap electrodes,
• an ion generator for creating ions inside said inter-electrode space or creating ions outside said space and introducing the ions thereinto,
• a trapper for trapping created ions in said inter-electrode space where said radio frequency electric field is formed,
• an alternating current (AC) electric field generator for generating in said space a wideband auxiliary AC electric fields which comprise plural different frequency components, the frequency range of which are corresponding to the mass-to-change ratio range of undesired ions to eject the undesired ions by resonant ejection;
• and
• a detector for sequentially separating the ions trapped in said space in terms of mass according to the particular mass-to-charge ratio of the ion and detecting the mass of these ions after the trapped ions have been emitted from said space;
• the strength of wideband auxiliary AC electric fields comprising the frequency components within the required frequency range is varied according to the strength of the radio-frequency electric field generated in said space;
• wherein the changer for changing the strength of said wideband auxiliary AC electric fields according to the strength of the radio-frequency electric field generated in said space applies, between said ring electrode and end cap electrodes, wideband auxiliary AC voltages comprising the different frequency components within the required frequency range, and varies said wideband auxiliary AC voltages according to the strength level of the radio-frequency electric field generated in said inter-electrode space, and
• wherein the change for changing the wideband auxiliary AC voltages consisting of the different frequency components within the required frequency range varies the differences of frequency between the adjoining frequency components of each auxiliary AC voltage of the different frequencies within the required frequency range according to the frequencies of each frequency component at said wideband auxiliary AC voltages.