Abstract

The continuous emergence of NPS over the last years poses a series of novel challenges for
forensic analysts. Most of those new compounds are synthesized with minimal chemical
modifications to the structure of already known chemicals in order to avoid regulations. Some
of these new compounds may undergo chemical changes during analysis leading to
misidentification and detrimental legal consequences. GC–MS is one of the most widely used
analytical techniques employed by forensic laboratories all over the world for drug analysis.
Nevertheless, thermolabile NPS, such as 25I-NBOH can generate artefacts in the traditional GCMS
analysis. In this paper, we describe the fragmentation mechanism of the 25I-NBOH into a
major peak corresponding to 2C-I and a minor one corresponding to the associated orthophenolic
benzyl ether (o-PBE), which exact identity is directly linked with the solvent used for
the analysis. Also, a series of method adjustments is displayed, encompassing variation on the
injector temperature, split ratio and flow ratio, although with no success to prevent 25I-NBOH
thermo degradation in the GC injector. Furthermore, differential scanning calorimetry and
thermogravimetric analysis demonstrated that 25I-NBOH´s thermal stability is due to a smaller
temperature window between fusion and decomposition points. Finally, we perform
derivatization experiments and demonstrate how to overcome 25I-NBOH degradation in the
GC/MS analysis.