A method for multiple reaction monitoring using a
mass spectrometer (106) is proposed. The method comprises i) measuring (128), using a
mass spectrometer (106), multiple reaction monitoring transitions of both a quantifier and a qualifier of both an
internal standard and an
analyte using alternating multiple reaction monitoring, the alternating multiple reaction monitoring comprising at least three multiple reaction monitoring channel groups, one of the multiple reaction monitoring channel groups being measured at the respective theoretical m / z values of both the quantifier and the qualifier of both the
internal standard and the
analyte, and the two other multiple reaction monitoring channel groups being measured at respective m / z values shifted by a predetermined level higher and lower; ii) comparing (130), for at least two of the groups, at least two of the quantifier / qualifier ratios of the multiple reaction monitoring transitions of the
internal standard with reference values from a
database (126) using at least one
processing device (120), the comparing including determining a deviation between the quantifier / qualifier ratio and the reference value; iii) determining (132), if at least one deviation of the quantifier / qualifier ratio is within at least one predetermined tolerance range, using a
processing device (120), a measurement result from the measured multiple reaction monitoring transitions of the
analyte and the internal standard, and, if not, rejecting (136) the measured multiple reaction monitoring transitions; and including.