Abstract: Instrument for analysing compounds, comprising an ion source, an adjacent drift tube and a mass spectrometer including an ion detector for separation and detection of product ions, wherein instrumental parameters of the instrument can be altered by actuating elements for actuating variables of at least one of the group consisting of ion source, adjacent drift tube, mass spectrometer and ion detector, characterized by a controlling unit which is connectable to a storage device, wherein the storage device comprises a specification for certain compounds, the specification for each compound comprising a set of data comprising at least two different instrumental parameters and corresponding intensity signals for product ions detected with the ion detector, wherein the controlling unit alters the actuating elements in accordance with the specification for each compound, wherein a correspondence signal is displayed on a display unit if the detected intensity signal for the product ion corresponds with the stored int