A method for determining in a sample, by mass spectrometry, the presence, absence, or amount of one or more analytes is described herein. The run time is less than six minutes. The method includes subjecting the sample to an ionization source under conditions suitable to produce one or more ions detectable by mass spectrometry from each of the one or more analytes, wherein the one or more analytes are derivatized prior to ionization; measuring, in a single injection, by mass spectrometry, the amount of the one or more ions from each of the one or more analytes; and using the measured amount of the one or more ions to determine the amount of each of the one or more analytes in the sample.