A system for rapidly screening samples, the system comprising: a tandem mass spectrometer that includes a quadrupole mass filter that allows independent control of both the radio frequency voltages and direct current voltages; a sample introduction device that is non-chromatographic and that is configured to supply the tandem mass spectrometer with a sample of a plurality of samples; and a processor in communication with the tandem mass spectrometer and the sample introduction device that is configured to: instruct the tandem mass spectrometer to perform a survey scan of the sample supplied by the sample introduction device to obtain a precursor mass spectrum, determine a mass distribution of precursor ions in the sample from the precursor mass spectrum to define two or more precursor mass selection windows across an entire mass range of interest of the sample, wherein at least two of the two or more precursor mass selection windows have different window widths, wherein the different window widths are set to values based on complexities of the plurality of samples, such that wider windows widths are used where the plurality of samples have a sparse number of ions, and narrower window widths are used where the plurality of samples have a large number of ions; and instruct the tandem mass spectrometer to perform fragmentation scans at the two or more precursor mass selection windows across the entire mass range of interest of the sample by independently controlling the RF voltages and DC voltages of the quadrupole mass filter of the tandem mass spectrometer. a tandem mass spectrometer that includes a quadrupole mass filter that allows independent control of both the radio frequency voltages and direct current voltages; a sample introduction device that is non-chromatographic and that is configured to supply the tandem mass spectrometer with a sample of a plurality of samples; and a processor in communication with the tandem mass spectrometer and the sample introduction device that is configured to: instruct the tandem mass spectrometer to perform a survey scan of the sample supplied by the sample introduction device to obtain a precursor mass spectrum, determine a mass distribution of precursor ions in the sample from the precursor mass spectrum to define two or more precursor mass selection windows across an entire mass range of interest of the sample, wherein at least two of the two or more precursor mass selection windows have different window widths, wherein the different window widths are set to values based on complexities of the plurality of samples, such that wider windows widths are used where the plurality of samples have a sparse number of ions, and narrower window widths are used where the plurality of samples have a large number of ions; and instruct the tandem mass spectrometer to perform fragmentation scans at the two or more precursor mass selection windows across the entire mass range of interest of the sample by independently controlling the RF voltages and DC voltages of the quadrupole mass filter of the tandem mass spectrometer. instruct the tandem mass spectrometer to perform a survey scan of the sample supplied by the sample introduction device to obtain a precursor mass spectrum, determine a mass distribution of precursor ions in the sample from the precursor mass spectrum to define two or more precursor mass selection windows across an entire mass range of interest of the sample, wherein at least two of the two or more precursor mass selection windows have different window widths, wherein the different window widths are set to values based on complexities of the plurality of samples, such that wider windows widths are used where the plurality of samples have a sparse number of ions, and narrower window widths are used where the plurality of samples have a large number of ions; and instruct the tandem mass spectrometer to perform fragmentation scans at the two or more precursor mass selection windows across the entire mass range of interest of the sample by independently controlling the RF voltages and DC voltages of the quadrupole mass filter of the tandem mass spectrometer.