Patent ID: 9076638
Filing Date: 2015-07-07
Classification: H01J

Abstract:
1. A mass spectrometric method comprising: ionizing a sample and an internal standard having a known concentration in an ion source; introducing sample ions and internal standard ions into an ion trap; accumulating the sample ions and the internal standard ions in the ion trap at the same time; mass-selectively ejecting and detecting the internal standard ions from the ion trap for each accumulating step of a measurement sequence of the ion trap, where the sample ions have been accumulated in the ion trap; and thereafter, isolating precursor ions from the sample ions in the ion trap; dissociating the precursor ions to generate fragment ions; mass-selectively ejecting and detecting the fragment ions from the ion trap for each accumulating step of the measurement sequence of the ion trap; and calculating a concentration of the sample on the basis of an intensity of the detected internal standard ions and an intensity of the dissociated fragment ions of the sample, where the internal standard ions and the sample ions are accumulated at the same accumulating step of the measurement sequence of the ion trap.