Determination of ‘common-batch’ members in a set of confiscated 3,4-(methylendioxy)-methylamphetamine samples by measuring the natural isotope abundances: a preliminary study

C/'3C natural isotopic abundances have been measured in a randomly chosen set of con- fiscated 3,4-(methylenedioxy)methylamphetamine (MDMA, XTC, Ecstacy) tablets using on- line gas chromatography isotope ratio mass spectrometry. The high precision obtained with this method allowed the discrimination of at least four different groups of MDMA tablets according to variations in their natural 13C/'2C isotopic ratio. It is shown that further discrimination can be obtained by using the "N/14N isotopic ratios in MDMA.