Reference features are updated based on a previous scan during each mass spectrometry scan of a sample. Reference features with reference feature confidence values are generated from a plurality of initial scans. For each subsequent scan of a sample, sample features and sample feature confidence values are calculated. The reference features and sample features are aligned to determine common features. Constants are determined for an equation of mass of the mass spectrometer using confidence weighted regression of the common features. The constants and the equation of mass are used to calculate new mass values for the sample features. The reference features are updated using the sample features and the reference feature confidence values are recalculated in order to maintain the accuracy of reference features for calibration.