Presumptive and Confirmatory Drug Tests

Tests for illegal drugs were performed on unknown, white powder substances obtained from over-the-counter cold medicines such as Sudafed and Contac. Both presumptive tests and confirmatory tests were conducted. It was shown that substances that tested positive for the qualitative Marquis color test were found to be false positives for illegal substances such as heroin or methamphetamine when samples were subjected to GC–MS analysis. The samples that contained dextromethorphan hydrobromide or pseudoephedrine hydrochloride were first extracted from the white powders as free base amines. Scopolamine hydrochloride, the identification of which can be confirmed by infrared spectroscopy, shows a false positive for cocaine hydrochloride with the cobalt thiocyanate reagent.