Patent ID: 7989764

Claim:
A method of ion trap spectrometry comprising the steps of: ionizing a sample using an ion source; trapping ions generated by the ion source using an ion trap part; applying a main high frequency voltage to the ion trap part using a main high frequency power source; applying an auxiliary high frequency voltage to the ion trap part using an auxiliary high frequency power source; detecting ions ejected from the ion trap part using a detector; accumulating desired ions into the ion trap part by ejecting undesired ions while accumulating ions into the ion trap part; ejecting undesired ions that remain in the ion trap part and leaving the desired ions in the ion trap part, wherein the accumulating and ejecting steps are repeated alternately; breaking ions by carrying out a collision induced dissociation to the desired ions to break the ions after the accumulation step and the undesired ion ejection step are repeated; and mass-separating for ejecting broken ions on the basis of each mass and for detecting the same in the detector, wherein: the quantity of desired ions is adjusted to a predetermined value that is optimal for MS/MS measurement by calculating the number of times the accumulating step should be repeated to achieve the predetermined value and repeating the accumulating step and the ejecting step the calculated number of times.