Monoclonal Antibody-Based Immunoassay is our preliminary drug detection technique to selectively detect levels of specific drugs in biological fluid specimens. Immunoassay is based on the binding reaction of a target substance, known as an antigen, with its respective antibody. These antibodies identify and bind to specific natural and synthetic antigens present in the body including drugs. This mechanism is similar to a single key being specifically made to open a single lock. The immunoassay used to detect preliminary drug contents is based on the principle of competitive binding. Prior to the test, a fixed antibody is bound by a substitute molecule known as a conjugate. If the presence of a drug is detected, the drug antigen in the sample will displace the substitute molecule as it has competed for binding with its specific antibody; this event produces a detectable signal.
Mass Spectrometry (MS) is a technique that measures the mass-to-charge ratio of charged molecules to determine mass, composition, and structure of chemical compounds. It has gained popularity as a diagnostic tool in the field of clinical biochemistry due to the ease of assay development, small sample quantity required and the ability to measure multiple analytes at once. It is a powerful analytical technique for the identification of drug metabolites in biological specimens such as urine, blood, and saliva.
Gas Chromatography - Mass Spectrometry (GC-MS) has historically been the gold standard for analyzing biochemical compounds such as lipids, proteins and drug metabolites. It is composed of two main components: Gas Chromatography (GC) and Mass Spectrometry (MS). Gas chromatography is technique used for separating compounds that can easily be vaporized without decomposition. Once separated, the coupled mass spectrometer identifies the different separated and eluted substances based on the MS principle described above. One of the advantages of GC-MS is the reproducible fragmentation pattern for each metabolite which allows for easy identification based on known metabolite patterns stored in a database.