The Liquid Chromatograph Tandem Mass Spectrometer (LC-MS/MS) operates in a similar manner to the GC-MS with a few exceptions. Instead of using a gas mobile phase, the chromatograph uses a liquid mobile phase and the tandem mass spectrometers provide a greater sensitivity to trace amounts of compound. Like GC-MS, the LC-MS/MS is used to confirm the presence of the drugs that were found in the initial screening process. The liquid chromatograph tandem mass spectrometer has the advantage of the ability to look at a wider range of organic compounds in a sample, does not need the extra derivatization step and generally has improved sensitivity over a GC-MS.