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Interpretation of colour tests Colour descriptions

المؤلف:  Sue Jickells , Adam Negrusz (Editors)

المصدر:  Clarkes Analytical Forensic Toxicology

الجزء والصفحة:  340

2026-11-01

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Interpretation of colour tests

Colour descriptions

Colours exhibited by these tests cannot be described with any accuracy. They may vary in intensity or tincture with the concentration of compounds in the test samples and the presence of extraneous material. In addition, their assess ment is always a subjective one, even in people with normal colour vision. For example, the Marquis test is stated to give a black or blue-black colour with MDMA and a green-black with lysergide. Even in the pure form these colours may not be readily distinguishable; add this to the fact that most drugs of abuse are more routinely encountered diluted with a variety of other substances, and one can begin to appreciate the difficulties that can arise in the real world with colour tests. Some of the complexes formed are unstable, so that the colour changes or fades with time.