Did SPME Make It into the Clinic?

Looking back to our 2013 article, we can say that our SPME predictions were broadly correct – at least at the research level. For example, we designed an automated 96-coated-blades system that is compatible with multi-well plates, which we have used in a number of different applications, including biological fluid analysis for range of target metabolites and drugs, as well in LC-MS- based metabolomics.

We have also designed medical devices based on coated fibers for both in-vivo SPME metabolomics and targeted determinations in various organs, involving both animal models as well as human tissues. Initial human trials involving several hospital surgery teams have already been published. And we’re confident transplant surgery and oncology both stand to benefit.

In addition, the combination of high throughput and miniaturization has proved powerful in biotechnology – enabling different in vitro analyses, including targeted and untargeted cell line studies cultured as three-dimensional models.

In terms of surprises, we have been pleased to see (when using SPME with matrix compatible coating) a balanced coverage of analytes and low matrix effects compared with solvent extraction approaches. This observation led to developments in the in-vivo metabolomics area, as well as direct mass spectrometry applications, which are very powerful. One such technique, Coated Blade Spray (CBS), has been recently commercialized by Restek.

These observations also made us realize that the structure and performance of SPME is closer to typical sensor technology, rather than a traditional extraction technique – because the objective of SPME is to equilibrate with the system under investigation, rather than dissolving and/or precipitating sample components to quantitatively remove compounds of interest. But unlike ordinary sensors, SPME has high capacity, which opens the door to applications involving GC-MS, LC-MS, and direct MS readout, which facilitates multicomponent quantification – as opposed to electrochemical or spectroscopic determinations.

Another surprise is the number of ideas regarding new applications of SPME that have come up during our meetings with clinicians – either during projects or at conferences. These conversations highlight the importance of exchanging information and involving end-users as technology evolves.

Reflecting on where we’re at today, given the continuously growing number of citations and publications over the past decade – indeed since its inception in 1990 – SPME is still a “hot topic” of research. There are a number of scientists exploring the flexible format of the technology by proposing different types of devices, while others look into new material developments to design high-performance coatings. These efforts have resulted in further fundamental developments and applications addressing critical societal needs. 

Perhaps more notably today than 10 years ago (at least for some), SPME is very attractive as a “green” and sustainable tool; it eliminates the use of solvents, it consumes few materials, it uses little energy, it can be used multiple times in high throughput modes, and it facilitates on-site and in-vivo investigation. 

Our prediction for the next decade? Well, all these advantages should result in a range of SPME formats becoming available for a range of applications – alongside corresponding method development facilitating broader acceptance among the next generation of analytical chemists who are rightly concerned with sustainability.