How DART-MS hits the mark for point-of-need applications
Jeff Zonderman | | 4 min read | Opinion
The need for increasingly detailed and precise analytical information – in real-time and at the point-of-need – is accelerating. Consider the example of medics and organizers faced with the challenge of responding to extensive drug use at large scale events. Minimizing harm relies on rapid and reliable in-the-field substance identification, potentially involving new psychoactive substances (NPSs), polydrug mixtures, and an array of drug contaminants. Sending samples back to a lab is neither practical nor sufficiently quick. A better analytical solution is needed.
And there are many other examples – from security screening for explosives, food ingredient checking for harmful contaminants, routine medical testing, and evidence sifting for crime-related substances.
Mass spectrometry (MS) is the gold standard analytical measurement technique in many fields, prized for its ability to deliver chemical signatures for an analyte. Direct Analysis in Real-Time (DART) enables rapid desorption and ionization of an incredibly broad array of sample types. Together, they are able to meet requirements for point-of-need analysis, in airports, clinics, and mailrooms, on factory floors, and, quite literally, out in the field. How powerful could this combination be?
Point-of-need applications necessarily prioritize speed, size, ease-of-use, and reliability. These are all increasingly desirable in lab settings too, but the bar is set higher out in the field. In some cases, equipment and critical ancillaries must be mobile. Screening is often a 24/7 activity with delays and downtime equating to unacceptable log jams. Crucially, users of point-of-need systems are not analysts. They may have only minimal understanding of the technique/technology and limited time or ability to troubleshoot. Often, the end user simply demands a red or green light answer – other applications are far more involved.
DART-MS is an inherently simple approach that uses a charged gas pulse to deliver non-contact surface sampling and requires little-to-no sample preparation (a far cry from conventional LC and GC techniques). In a DART system, a corona discharge converts a flowing inert gas – helium or nitrogen – into a plasma. Electrostatic filtration refines this plasma to a stream of excited atoms or molecules that initiate a cascade of gas phase reactions, ionizing the sample, at the entry to the MS system.
DART works at atmospheric pressure, requires little to no sample prep, nor the high level of organic solvent most conventional chromatography uses today, and is very fast. Solids, liquids, and gases can all be analyzed in their native form. The user simply swabs, spots, dips or scans and detects. DART-MS systems can analyze a single sample in seconds or 384 well plates in less than 25 minutes. Such features make the technology inherently amenable to point-of-need applications and, in many instances, set it apart from chromatographic techniques.
However, for DART-MS to deliver its full potential outside of the lab, I believe we need a shift in focus – away from flexibility and towards commoditization. For MS, a primary focus is simplification and the development of systems that are more mobile. Complex LC and GC interfaces inhibit this work. In contrast, the flexibility and simplicity of DART is a defining attraction. These features make DART an easy bolt on to any MS system which is, and will continue to be, important for lab applications. But out of lab applications are going to be better served by fully integrated DART-MS systems, rigorously optimized for point-of-need use.
Going forward, integrating DART with a defined, miniature MS system will make further refinement easier. We’ll be able to shrink the technology, optimize the DART-MS interface, streamline support and maintenance, and maximize reliability.
In addition, we’ll be able to generate large amounts of strictly comparable data providing a foundation for improved data analysis and application. Currently, DART is used with many different mass spectrometers including single and triple quadrupole systems, iontrap, TOF, Orbitrap and other MS detector techniques. I believe this compromises the development of a single unified data library. A degree of standardization will address this issue and generate wider, larger datasets than are available in the more fragmented landscape that currently prevails.
In my view, now is the right time for DART-MS to launch confidently from the lab to provide better solutions for food, forensics, and security – already big users of this technology – and to tackle previously unmet needs in other sectors, such as clinical, pharmaceutical and environmental.
Returning to that original example of minimizing harm from drug use, a recent study of discarded drug packaging by researchers at the University of Melbourne (1) illustrates just how well DART-MS answers this requirement. As someone working at the forefront of this powerful technology (in case you missed the news, Bruker acquired IonSense, the innovator of ambient DART ionization technology, in April 2022), I look forward to seeing more applications materialize over the coming decade. I expect DART-MS will ultimately evolve into a workhorse tool, taken for granted by non-expert users in all walks of life – perhaps the best accolade for any analytical technique.
- H West et al., “Early Warning System for Illicit Drug Use at Large Public Events: Trace Residue Analysis of Discarded Drug Packaging Samples,” J of Am Soc for Mass Spectrometry, 32, 10, 2604-2614 (2021). DOI: 10.1021/jasms.1c00232