Presumptive tests amphetamines

Having recorded all of the physical data, the items to be examined chemically should be chosen. At the time of writing, there is no agreed best-practice protocol for undertaking this and the analyst should work within the requirements of the judicial system in which he/she is operating. The theory applied to powdered amphetamines can be equally applied to amphetamine tablets. The latter should be sampled and presumptive tests, TLC and confirmatory tests then carried out. 

Although when using this combination of presumptive tests and TLC it is possible to discriminate within this group of compounds, due to the extremely large number of amphetamines available, it is necessary to carry out a confirmatory analytical technique. The foremost of these, for amphetamine identification, is gas chromatography-mass spectrometry (GC-MS). 

A number of difficulties are associated with colour tests on fresh and dried plant material, in addition to those associated with analysing a primary amine such as mescaline. These include the fact that the plant material itself may obscure the colour reaction that takes place. Furthermore, a wide range of primary phenethy-lamines and amphetamines may yield similar colour reactions. The presumptive test which can be satisfactorily used is the Marquis test (see Appendix 1). Positive and negative control tests should also be carried out. An orange-red colour will develop if mescaline is present. However, due to the difficulties associated with interpretation of such results, further confirmation of the presence of mescaline, by using chromatographic and spectroscopic techniques, is required. 

Several presumptive tests are available for barbiturates and benzodiazepines. These are not as general as those used for other drug classes (for example, the Marquis test for opiates and amphetamines (including ring-substituted species)), but have the disadvantage that they do not discriminate between the drugs within the specific class. These tests are described in the following sections. 

Mandalin tast A presumptive test for amphetamines and alkaloids. The Mandelin recent is a 1% solution of ammonium vanadate (NH4VO3) in concentrated sulphuric acid. Different substances j e different colours. Mescaline, for example, produces an orange colour, heroin abrown colour, and amphetamine ablue-green colour. 

The initial screening test for amphetamine and metham-phetamine is typically immunoassay. For confirmation of a presumptive positive test, a quantitative drug measurement is performed using GC-MS. 

Workplace drug testing typically involves the analysis of urine samples from job applicants and/or employees to determine whether they have recently used drugs of abuse such as heroin, marijuana, amphetamines or cocaine. Test samples are normally screened by a relatively inexpensive immunoassay, and all presumptively positive samples are submitted for mass spectral analysis to confirm the presence of the drug or drugs. Similarly, for determination of... 

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