19F and 1H quantitative-NMR spectroscopic analysis of fluorinated third-generation synthetic cannabinoids

Abstract

Quantitative nuclear magnetic resonance (q-NMR) spectroscopy is a robust and reliable analytical method that possesses many advantages over conventional chromatographic techniques used in drug analysis. In this paper, the application of ¹⁹F and ¹H NMR spectroscopy to quantify the amounts of synthetic cannabinoids (SCs), AM-694 and 5F-ADB, in herbal incense packages is discussed. These SC samples, seized in the South West of England in the summers of 2016 and 2017, are part of a growing illicit drug problem in the UK. For accurate quantitative analysis using ¹⁹F observe, the data acquisition and the NMR processing parameters, such as spectral width, the centre point of the spectrum, nuclear Overhauser effect (NOE) enhancement and relaxation delay, are discussed together with cross-method validation. The reproducibility, simplicity, high speed, and non-destructive nature provide reliable quantitative analysis and, by using ¹⁹F NMR, there is essentially no background interference. This quantitation is without resorting to the use of (often unavailable) standards as reference materials or to lengthy sample preparation, which are the norm in many analytical chromatographic techniques. The NMR methods allowed a direct comparison between ¹H and ¹⁹F NMR, revealing the robustness and the effectiveness of ¹⁹F NMR for application as a rapid (∼8 min), quantitative analytical method for fluorinated SCs which are now being seized with an increasing frequency and are highly toxic.