Conventional Confirmatory methods

The conventional or traditional methods of confirmation of drug testing didn’t use mass spectrometers. Rather, they were reliable of other techniques and some chemical tests which confirmed and identified the compound. These methods and techniques were insufficient as they were dependent on many tests to confirm the compound. Later, colorimetric tests, immunoassays and chromatography started. GC and LC i.e. Gas and Liquid chromatography is one of the best means to identify the drugs and their metabolites. This is so because GC has variety of detectors which improve the selectivity and the sensitivity of this method. NPD – Nitrogenous Phosphate Detectors also provide increased sensitivity as many illegal drugs contain plant derivatives having nitrogen. Drugs which have halogens like benzodiazepines are detected at lower concentrations using ECD – Electron Capture Detector. The LC utilizes a UV-visible spectrometer which identifies and detects the presence of drugs in liquids by absorbing their UV rays. These along with other techniques greatly limited the possibility of false positive results.

Presently, the conventional method used is the GC-MS technique which is mandatory in the workplace drug testing regimes in the US. A drug test of greater sensitivity, the GC-MS uses two coupled instruments for analyzing. The GC divides the compound from interfering compounds while the MS structurally recognizes the compound. Together, they identify the drug just like ‘fingerprints’. This method is very commonly used and is accepted all over the world. More than 4.4 million samples were identified in 2007 in the urine testing program of Department of Defense which used GC-MS as their confirmatory test technique.

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