Patent ID: 7161141

Claim:
An ion trap/time-of-flight mass spectrometer including a liquid chromatograph having a column for separating a sample, an ion source for ionizing the sample eluted from said liquid chromatograph, an ion trap capable of temporarily trapping ions, a time-of-flight mass spectrometer, and a data processing unit for collecting detection results of said time-of-flight mass spectrometer, said ion trap/time-of-flight mass spectrometer comprising: means for introducing a reference sample having a known mass value to said ion source in match with elution of the sample from said liquid chromatograph, wherein said data processing unit collects data detected by said time-of-flight mass spectrometer through the steps of causing a precursor ion to be selectively left from among ions of the sample as a measurement target, exciting and fragmenting the precursor ion to produce a product ion, introducing ions of the reference sample to said ion trap, and expelling, out of said ion trap, the product ion and the reference sample ions both trapped in said ion trap, thereby correcting an accurate mass of the product ion based on the measured reference sample ions.