Methods and apparatus for mass filtering based on a-priori biomarker knowledge and elution time intervals for selected ion species from a separation device. A sample may be screened for biomarker patterns based on distinct elutions times for selected ions or peptides. A mass spectrum for species of interest can be tailored by filtering out undesired ions by measuring corresponding elution times and determining a priori selected elution time intervals for desired ion species only. The invention assists in the identification of biomarkers having known mass spectral peaks corresponding to known proteins or ions of interest that are known to elute from a separation device within a pre-defined elution time window.
A method of controlling the population of ions in a mass spectrometer in which a first sample of ions is provided in the mass spectrometer, a measure of abundance of a species of interest in the first sample of ions is determined, the measure of abundance comprising an intensity value, and a second sample of ions is introduced into the mass spectrometer. The second sample of ions is introduced in an amount determined at least in part on the measure of abundance of the species of interest in the first sample of ions.
Systems and methods for analyzing compounds in a sample. In one embodiment, a mass spectrometer includes an ion source for emitting a plurality of ions from a sample together with a detector positioned downstream of said ion source and configured to detect the impact of emitted ions on the detector. The mass spectrometer also includes a controller operatively coupled to the detector and to the ion source and configured to calculate the m/z for each detected ion. The controller comprises a mass defect filter configured to determine if the m/z for each detected ion falls within a pre-determined mass defect range. The mass spectrometer also includes data storage coupled to the controller, wherein the data storage is configured to store detected ion m/z data corresponding to the m/z for a detected ion if the m/z falls within the mass defect range. The mass spectrometer may also include an ion mass filter positioned downstream of the ion source and operatively coupled to the controller. The ion mass filter is configured to selectively filter for ions substantially corresponding to the stored detected ion m/z data. The spectrometer may also include a fragmentor operatively coupled to the ion mass filter, wherein the fragmentor is configured to fragment each selected ion and to emit each fragment towards the detector. The controller is operatively coupled to the fragmentor and configured to calculated the m/z for each fragment detected by the detector. The data storage is preferably further configured to store fragment m/z data corresponding to the m/z for each detected fragment.
