A recent Microgram Journal paper by Casale and Hays at the US Department of Justice Drug Enforcement Administration (Volume 9, Number 2) reported the characterization and differentiation of 11 commonly encountered N-BOMe derivatives via mass spectrometry and infrared spectroscopy. The authors noted that the NBOMe classes of compounds are high boiling late eluting compounds with respect to gas chromatography. The NBOMe’s exhibit very low molecular ion abundance ranging from 0.05 to 1% and also exhibit a very strong base peak at 121.

The ratio of 150 m/z to 226m/z has been reported as a differentiating factor between the n-propylthio (T7) and isopropylthio (T4) isomers. We found no consistency of the 150/226 ratio when comparing the data reported in the Microgram Journal with the data provided by Cayman Chemical, or with the GC/ MS data obtained on our sample. The 150/226 ratio is dependent on the tuning of each mass spectrometer which may explain the lack of consistency between laboratories. The differentiation of NBOMe’s and related isomers is readily accomplished in the Infrared spectra.

In this application note we compare the infrared spectra of the available standards of the 2’methoxy benzyl compounds where the R group in the structure above is n-propylthio, or isopropylthio. The N-BOMe compounds are highly potent, with dosage typically in the microgram range. Distribution on tabs of blotter paper has been observed (similar to LSD cases). The low dosage may require microgram sensitivity for detection with casework samples. The DiscovIR-GC® system provides high quality Infrared spectra from Nano grams of sample.

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