An alternative method to sweeping masses with a quadrupole mass filter of. constant U/V is suggested. It consists in keeping the relative values of 27 and V such that the absolute resolution ΔA equals 1. The resulting transmission and allowable injection voltages are thereby kept maximum throughout the spectrum, while the resolution obtained is ideally suited for most kinds of mass spectrometric work in atmospheric research. The circuit modifications required can easily be applied to all existing amplitude-swept quadrupole mass filters.