Analytical system and method

An analytical system comprising

• a mass spectrometer and an ionization source coupled to the mass spectrometer,
• an analytical fluidic system connectable to the ionization source via a downstream valve for infusing samples into the mass spectrometer via the ionization source, wherein the downstream valve is located downstream with respect to the analytical fluidic system in a normal direction of flow through a fluidic stream towards the ionization source,
• a downstream pump fluidically connectable to the ionization source via the downstream valve, wherein the downstream pump is fluidically connected to a plurality of fluid containers comprising respective fluids, the fluids comprising at least one concentrated composition for calibrating the mass spectrometer and at least one diluent for diluting the at least one concentrated composition,
• a controller configured to control the downstream pump in order to obtain at least one diluted composition by automatically mixing at least one concentrated composition with at least one diluent with a predetermined dilution factor, to infuse the at least one diluted composition into the ionization source, to obtain a mass spectrum of the at least one diluted composition and to execute a calibration of the mass spectrometer based on an assessment of the mass spectrum.