Insights From Industry

You Also Conduct Work With Coffee. Why Is Coffee Another Important Product in the Food Industry That Must Be Authenticated?

The coffee supply chain is very long. Coffee only grows in tropical countries, but it is processed and consumed worldwide. Because of this, highly valued Arabica coffee is susceptible to fraud because once the beans have been roasted and ground, it is practically impossible to detect differences solely by visual inspection. A form of analytical test is necessary, so we wanted to find out if benchtop NMR could address this problem.

A proton NMR spectrum of the lipophilic phase taken from a ground roast coffee includes a range of signals, from primary metabolites, breakdown products, and minor compounds from the roasting process. At 60 MHz, a large number of these peaks overlap, and so it is only possible to pick out the more major compounds.

Conversely, caffeine gives us some clear, easy to recognize signals. And critically, a small isolated peak can also be seen from a compound called 16-O-methylcafestol, or 16-OMC, which is noteworthy because it seems to be present in extracts from Robusta yet not Arabica coffees.

This could potentially offer a pathway to a rapid, easy, and cost-effective authenticity test.

Can You Tell Us About Using Benchtop NMR to Identify Psychoactive Drugs?

This work began a couple of years ago. We had been asked to develop a benchtop NMR test capable of rapidly identifying novel psychoactive drugs, also known as designer drugs or legal highs.

Since then we have expanded this work to examine small-molecule pharmaceuticals, alongside investigating controlled substances more widely. This work has been undertaken in collaboration with Manchester Metropolitan University, an organization which holds one of a handful of UK licenses for the synthesis and storage of these substances.

My work within this particular project has been focused on automated data analysis. The challenges with this area, especially with seized drug samples, have included factors such as degradation of samples from uncontrolled storage, unknown concentrations of active ingredients, and samples that have been mixed with other substances. Thankfully, we now have a working routine that is able to identify a completely unknown sample, for example, a single compound, or even a mixture with excipients or other active substances. This routine is achieving very high accuracy.

The approach uses pattern matching against a database of reference compounds, working based on the identification of several nearest neighbours with some extra manipulations that help it work with mixtures. A patent application for this method is currently in progress.

We begin with a spectrum of the unknown sample, pre-processing it to extract only the regions of interest that we want to look at. So, for example, we could exclude peaks from the solvent.

The next step in the process is a comparison of the sample spectrum using a database of known compounds. This database includes controlled substances, pharmaceuticals, and a series of excipients - several hundred reference spectra overall. The closest matches are then ranked in order of similarity.

If a close match is not found, this could indicate a mixture. In these cases, combinations of the top single compound matches would be used to synthesize a further collection of mixture spectra via spectral addition. Finally, the sample spectrum will be compared against these mixtures, identifying the best overall match.

This method and work were recently published in an open-access paper. We looked at more than 400 seized samples in total, throughout the study. Our work allowed us to conclude that benchtop NMR, working alongside pattern recognition technology, offers a highly effective tool for the rapid screening of seized street drugs. In fact, throughout the study, we were able to successfully identify controlled substances in 99 % of the samples that we analysed.