Forensic Research & Technology

Biography

Biography: Pierrick Nun

Abstract

Isotopic quantitative NMR (iqNMR) has been successfully applied to ²H since the 80’s (SNIF-NMR). Recently, EBSI team has been able to extend it to ¹³C.¹ It is now possible to measure with a precision as low as 1‰, the ¹³C/¹²C ratio on each carbon (δ¹³C_i), giving a lot more information than the global ¹³C/¹²C ratio on the whole molecule (δ¹³C_g) obtained from isotope ratio measurement by mass spectrometry (irm-MS). Indeed, only knowing the mean δ¹³C_g could be misleading. If the measured value is null, is it because there is no fractionation or because there is counteractive normal and inverse isotopic effects on different positions? Quantitative ¹³C NMR has already been successfully applied to a range of molecules including glucose, vanillin, paracetamol and aspirin and used to show the position-dependent isotopic fractionation occurring during reactions or purifications. We developed new applications of this powerful technique. In environmental studies, ¹³C iqNMR can be used to study the fate of pollutants. As an example, oxidation of a fuel additive, Methyl tert-butyl ether has been done. MTBE was oxidized by potassium permanganate and the eventuality of a position-specific fractionation has been investigated. In the actual debate around the origin of Tramadol, natural or anthropogenic, mean values cannot give a clear answer and ¹³C iqNMR can help to establish a possible biosynthetic pathway. The isotopic fingerprint could provide a unique tool for the authentication of drugs, depending of their synthesis, manufacturer or the origin of reactants