Benchtop NMR spectroscopy in the analysis of substandard and falsified medicines as well as illegal drugs.

Substandard and falsified medical products may cause harm to patients and fail to treat the diseases or conditions for which they were intended. It is therefore required to have analytical methods available to assess medical product quality. Benchtop NMR spectroscopy provides a generic, inherently quantitative, analytical method capable of separating specific signals from those of a matrix. We have developed an analytical method for the analysis of active ingredients in pharmaceutical products and illegal drugs, based on benchtop NMR spectroscopy. Within its resolution limits, benchtop NMR spectroscopy is useful in determining the identity of the active ingredients in products containing acetaminophen, aspirin, caffeine, diclofenac, ibuprofen, naproxen, sildenafil, tadalafil and sibutramine, cocaine, and gamma hydroxybutyric acid, with a limit of detection of about 1 mg/mL. Furthermore, the content of the active ingredient can be determined with an error of 10%. Additionally, a chemometrics approach is shown to be useful to classify spectra in order to identify the active substances present in the sample, reducing the need for expert interpretation of the spectra acquired.