WhereAst, is the analyte peak area, in area units, in the chromatogram of the standard; Bst is the slope of the calibration curve;mst is the mass, in nanograms, of analyte in the standard;cst is the ordinate intersect of the calibration curve- if the calibration curve passes through the origin, cst=O.The mass of analyte, mA, in nanograms, present in the sample is calculated from the detector peak area using the response factor of the analyte: