Thin layer chromatographic screening for methaqualone, phenothiazines, opiates and benzodiazepines

A method is described which permits the simultaneous detection of methaqualone, phenothiazines, opiates and benzodiazepines in urine. Its diagnostic application is discussed. After cleavage of conjugates with hydrochloric acid, the substances are extracted and identified by thin-layer chromatography. In most cases analysis can be carried out using 2 solvent systems, phenothiazines, methaqualone and opiates being visualised using a three stage spray sequence. Since phenothiazines can interfere with the detection of methaqualone, a specific eluant is used to ensure reliable detection of the latter. Methaqualone can be positively identified by its characteristic metabolite pattern, whereas phenothiazines can only be detected as a group.