A system for extending the dynamic range of a quantitation calculation of a known compound of interest by combining two or more product ion extracted ion chromatograms (XICs) for the same product ion produced from two or more different precursor ions of the known compound of interest using a data independent acquisition method, comprising: (a) a sample introduction device configured to introduce a sample that includes one or more compounds of interest over time; (b) an ion source device configured to ionize the sample to transform the sample into an ion beam; (c) a tandem mass spectrometer configured to divide a precursor ion mass range of interest into a plurality of precursor ion mass selection windows for a DIA method and configured to perform the DIA method on the ion beam by, at each acquisition time of a plurality of acquisition times, for each precursor mass selection window of the plurality of precursor ion mass selection windows, to fragment precursor ions in the window producing product ions and to mass analyze the product ions produced, to produce a plurality of product ion spectra for each window of the plurality of precursor ion mass selection over the plurality of acquisition times; and (d) a processor in communication with the tandem mass spectrometer configured to (d)(i) receive a plurality of product ion spectra for each window of the plurality of precursor ion mass selection windows from the tandem mass spectrometer, (d)(ii) select a mass-to-charge ratio (m/z) value for at least one known product ion of a compound of interest of the one or more compounds of interest; (d)(iii) calculate an XIC for the m/z value from a plurality of product ion spectra for each of two or more different windows of the plurality of precursor ion mass selection windows, producing two or more XICs, (d)(iv) combine the two or more XICs into a single XIC that has a larger dynamic range, and (d)(v) calculate a quantity for the compound of interest using the single XIC. (a) a sample introduction device configured to introduce a sample that includes one or more compounds of interest over time; (b) an ion source device configured to ionize the sample to transform the sample into an ion beam; (c) a tandem mass spectrometer configured to divide a precursor ion mass range of interest into a plurality of precursor ion mass selection windows for a DIA method and configured to perform the DIA method on the ion beam by, at each acquisition time of a plurality of acquisition times, for each precursor mass selection window of the plurality of precursor ion mass selection windows, to fragment precursor ions in the window producing product ions and to mass analyze the product ions produced, to produce a plurality of product ion spectra for each window of the plurality of precursor ion mass selection over the plurality of acquisition times; and (d) a processor in communication with the tandem mass spectrometer configured to (d)(i) receive a plurality of product ion spectra for each window of the plurality of precursor ion mass selection windows from the tandem mass spectrometer, (d)(ii) select a mass-to-charge ratio (m/z) value for at least one known product ion of a compound of interest of the one or more compounds of interest; (d)(iii) calculate an XIC for the m/z value from a plurality of product ion spectra for each of two or more different windows of the plurality of precursor ion mass selection windows, producing two or more XICs, (d)(iv) combine the two or more XICs into a single XIC that has a larger dynamic range, and (d)(v) calculate a quantity for the compound of interest using the single XIC. (d)(i) receive a plurality of product ion spectra for each window of the plurality of precursor ion mass selection windows from the tandem mass spectrometer, (d)(ii) select a mass-to-charge ratio (m/z) value for at least one known product ion of a compound of interest of the one or more compounds of interest; (d)(iii) calculate an XIC for the m/z value from a plurality of product ion spectra for each of two or more different windows of the plurality of precursor ion mass selection windows, producing two or more XICs, (d)(iv) combine the two or more XICs into a single XIC that has a larger dynamic range, and (d)(v) calculate a quantity for the compound of interest using the single XIC.