Composition profiling of seized ecstasy tablets by Raman spectroscopy

Raman spectroscopy with far-red excitation has been investigated as a simpl e and rapid technique for composition profiling of seized ecstasy (MDMA, N- methyl-3,4-methylenedioxyamphetamine) tablets. The spectra obtained are ric h in vibrational bands and allow the active drug and excipient used to bulk the tablets to be identified. Relative band heights can be used to determi ne drug/excipient ratios and the degree of hydration of the drug while the fact that 50 tablets per hour can be analysed allows large numbers of spect ra to be recorded. The ability of Raman spectroscopy to distinguish between ecstasy tablets on the basis of their chemical composition is illustrated here by a sample set of 400 tablets taken from a large seizure of > 50000 t ablets that were found in eight large bags. The tablets are all similar in appearance and carry the same logo. Conventional analysis by GC-MS showed t hey contained MDMA. Initial Raman studies of samples from each of the eight bags showed that despite some tablet-to-tablet variation within each bag t he contents could be classified on the basis of the excipients used. The ta blets in five of the bags were sorbitol-based, two were cellulose-based and one bag contained tablets with a glucose excipient. More extensive analysi s of 50 tablets from each of a representative series of sample bags gave di stribution profiles that showed the contents of each bag were approximately normally distributed about a mean value, rather than being mixtures of sev eral discrete types. Two of the sorbitol-containing sample sets were indist inguishable while a third was similar but not identical to these, in that i t contained the same excipient and MDMA with the same degree of hydration b ut had a slightly different MDMA/sorbitol ratio. The cellulose-based sample s were badly manufactured and showed considerable tablet-to-tablet variatio n in their drug/excipient ratio while the glucose-based tablets had a tight distribution in their drug/excipient ratios. The degree of hydration in th e MDMA feedstocks used to manufacture the cellulose-, glucose- and sorbitol -based tablets were all different from each other. This study, because it c entres on a single seizure of physically similar tablets with the same acti ve drug, highlights the fact that simple physical descriptions coupled with active drug content do not in themselves fully characterize the nature of the seized materials. There is considerable variation in the composition of the tablets within this single seizure and the fact that this variation ca n be detected from Raman spectra demonstrates that the potential benefits o f obtaining highly detailed spectra can indeed translate into information t hat is not readily available from other methods but would be useful for tra cing of drug distribution networks.