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Microcrystal Tests

المؤلف:  Max M. Houck، Jay A. Siegel

المصدر:  Fundamentals of Forensic Science

الجزء والصفحة:  p345-346

2026-08-09

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Microcrystal Tests

In this test, a reagent or series of reagents are added to a suspected drug under carefully controlled conditions so that the drug forms a complex with the reagent(s) and is allowed to slowly recrystallize. The appearance, color, shape, and speed of crystallization are characteristic of particular types of drugs. Not all drug laboratories use microcrystal tests—their use has been declining over the past 25 years. In some parts of the country, especially in certain laboratories in California, microcrystal tests are used as confirmatory tests for a few selected drugs. In these situations, at least two different microcrystal tests are run along with other presumptive tests before a confirmation is declared. A certain percentage of these cases are also checked by another confirmatory test to make sure that the microcrystal tests are working properly. In other laboratories where micro crystal tests are used, they are considered to be presumptive tests that require further testing for confirmation. SWGDRUG considers microcrystal tests to be presumptive.

FIGURE 1 A field test kit. There are a number of different types of kits. In the type pictured here, a sample of suspected marihuana leaf is put into the thick, plastic envelope. There are three vials in the envelope. The envelope is squeezed so that each vial breaks. The contents are then shaken and, if marihuana is present, will turn purple. The vials on the left of the figure are single vial tests for different types of drugs.