The Feedstock Forensic Analysis was developed to give a compositional analysis of feedstock materials used for biodiesel production (fats and oils). This method uses standard gas chromatography at higher temperatures to give an approximation of diglyceride and triglyceride content, followed by mass spectroscopy (limited to a lower temperature) to give a breakdown of the free fatty acids, sterols, tocopherols, and any other compounds that may be present.