Validation of twelve chemical spot tests for the detection of drugs of abuse

Validation procedures are described for 12 chemical spot tests including cobalt thiocyanate, Dille–Koppanyi, Duquenois–Levine, Mandelin, Marquis, nitric acid, para-dimethylaminobenzaldehyde, ferric chloride, Froehde, Mecke, Zwikker and Simon’s (nitroprusside). The validation procedures include specificity and limit of detection. Depending on the specificity of each color test, between 28 to 45 drugs or chemicals were tested in triplicate with each of the 12 chemical spot tests. For each chemical test, the final colors resulting from positive reactions with known amounts of analytes were compared to two reference color charts. For the identification of unknown drugs, reference colors from the Inter-Society Color Council and the National Bureau of Standards (ISCC-NBS) and Munsell charts are included along with a description of each final color. These chemical spot tests were found to be very sensitive with limits of detection typically 1 to 50 μg depending on the test and the analyte.