This application note describes how to use the Agilent 1200 Series Rapid Resolution LC system and Agilent ZORBAX Rapid Resolution High Throughput columns to separate compounds in complex samples, how to calculate the empirical formula of unknown compounds from high mass accuracy data acquired with the Agilent 6210 time-of-flight and teh Agilent 6510 Q-TOF mass spectrometer, how to use the Agilent MassHunter Profiling software to quickly and computer-assistedly analyze complex mass spectrometry data, and how to use the Agilent MassHunter Profiling software to analyze the differences in related samples in different applications.