The MS Engine mass spectrometer (Hewlett Packard) consists of electron impact ionization (EI) and positive and negative chemical ionization (PCI and NCI) modes and a single quadrupole mass analyzer. The system is interfaced with a capillary gas chromatograph (Hewlett Packard) and is capable of 0.13 amu mass accuracy, m/z range of 10 to 1,000, positive and negative detection modes. The system is suitable for identification and quantitation of small compounds such as lipids, steroids, drugs and metabolites.