Characterisation of illicit ecstasy and diazepam tablets by colorant identification

Ecstasy and diazepam are two commonly abused drugs with a high potential for dependence. They are typically available as oral tablets that contain both the drug and other bulk components (excipients). Compositional knowledge of individual tablets offers a method of identification that can be used for profiling. Established analytical methods such as high performance liquid chromatography (HPLC) and liquid chromatography-mass spectrometry (LC-MS) are used to verify the nature and quantity of active components while differential scanning calorimetry (DSC) has proved valuable in providing unique thermal signatures' for the bulk composition. Analysis of the colorants commonly used in tablet aesthetics, however, has received very little attention so the aim of this work was to develop and validate such a method. HPLC-DAD was successfully used to characterise thirteen common colorants from five key classes of dyestuffs. Calibration data (R-2 0.999) was used to identify and quantify specific colorants in 63 out of 64 individual tablet cases with >98% success.