Agilent Technologies Gas Chromatograph/Mass Spectrometer: Mass Spectrometry is used to identify unknown compounds and quantify known compounds. It is sensitive and selective and is used in combination with a separation technique, Gas Chromatography, to analyze complex mixtures. In our laboratory, we use this technique to test body fluids (e.g.: serum, urine) for the presence of drugs of abuse as well as prescription drugs, which are also commonly abused.