Taking the Time out of Testing with Paper Spray Mass Spectrometry

Even non-scientific folks may be familiar with mass spectrometry as it seems to be frequently referenced on television shows. The tension builds as we're waiting on the "mass spec" to determine the exact results so the heroes can save the day. Unfortunately for the writers, but arguably great for everyone else, the drama of waiting for the "mass spec results" may be coming to an end as new research shows combining paper spray ionization with the power of mass spectrometry analysis, a technique known as Paper Spray Mass Spectrometry (PS-MS), could deliver reliable results in what feels like real-time.

The PS-MS process offers wide-ranging benefits, as it eliminates burdensome sample preparation, delivers results in seconds, and directly analyzes complex biological and/or environmental samples like soil, water, and aerosols, as well as whole biofluids like blood, urine, and saliva. PS-MS is able to analyze a complex matrix without sample preparation, so blood or urine can be tested directly.

One expert on this technique, Dr. Trevor Glaros, researcher in the BioDefense Branch at the US Army CCDC Chemical Biological Center in Aberdeen, Maryland, has published two different research papers within recent years demonstrating ways in which PS-MS could provide groundbreaking results for a wide range of applications, including the detection of chemical warfare agents, pesticides, and intoxicating nerve agents (among others) in on-the-ground warfare settings, traditional clinical settings, and everything in between.

In 2017, Glaros and his coauthors published a paper titled Detection of chemical warfare agent simulants and hydrolysis products in biological samples by paper spray mass spectrometry in the journal Analyst. This paper was featured on the cover of that issue, and went on to become the most downloaded research paper in the journal for all of 2017.  (http://doi.org/10.1039/c7an00144d)

In this research, Glaros and the team demonstrate that PS-MS improves upon existing low/no prep ionization techniques (partly because it eliminates the need for purified ionizing gas). Furthermore, with the industry developing new technology like plug-and-play paper spray cartridges and MS miniaturization, it's becoming increasingly possible to think about developing "on the ground" PS-MS applications to rapidly analyze samples in a wide range of situations, including active warfighters.

The researchers looked specifically at the effectiveness of analyzing five different known chemical warfare agents (CWAs), as well as their hydrolysis products, in human blood and human urine samples (procured by Innovative Research, Inc.) using paper spray ionization coupled to a high-resolution tandem mass spectrometer. They successfully demonstrated that PS-MS will analyze these biofluids using a method that requires no sample preparation, even when the CWA is in a complex matrix like blood or urine.

Their research concluded that PS-MS is able to analyze CWA parent simulants as well as hydrolysis products in linear and reproducible ways. Not only are these results robust and reproducible, but the analysis can take as little as one minute (whereas alternate methods currently take as long as 24 hours), and this analysis is more easily performed outside of traditional laboratory settings than other methods.

With the goal of broadening the use of paper spray mass spectrometry, Glaros and his colleagues turned to another potential application of PS-MS: identifying the original toxicant/agent in blood samples exposed to poisons like organophosphate pesticides or nerve agents like VX while simultaneously determining the inhibition of a critical enzyme, acetylcholinesterase (AChE), responsible for the regulation of neurological function. Without identifying the intoxicant, administering appropriate and timely countermeasures can be challenging.

Generally speaking, AChE catalyzes the hydrolysis of acetylcholine. When this function is interrupted by powerful inhibitors like pesticides and other poisons (including the nerve agent VX), it leads to disruptions in nerve signal transmission. Life-threatening, acute exposure will usually impact the respiratory centers in the brain stem, which often leads to fatal outcomes. The associated signs and symptoms of poisoning can vary greatly, depending on factors like the specific compound, the exact dosing, and the length of exposure.

The team's results were documented in the paper On-substrate Enzymatic Reaction to Determine Acetylcholinesterase Activity in Whole Blood by Paper Spray Mass Spectrometry that was published in Journal of the American Society for Mass Spectrometry in the December 2018 issue. (http://doi.org/10.1007/s13361-018-2072-1)

Glaros and his colleagues used a novel paper spray-based assay to not only measure the relative AChE activity in blood samples (procured by Innovative Research, Inc), but did so in a way that is also able to successfully identify the intoxicating nerve agent. In this work, they treated the paper surface to make it hydrophobic (water-repellent), which contained the reaction in-solution as a droplet on the surface during incubation. This research serves as an innovative example of an enzymatic reaction occurring directly on the surface of a paper spray ionization ticket, which could dramatically increase the applications of paper spray ionization-based diagnostic assays.

Additionally, PS-MS techniques can be expanded upon to screen samples quickly and easily with quantitative results to help solve issues like the backlog of samples in the criminal justice system. These techniques also have promising potential for use in clinical settings, with applications like bedside testing to monitor the effectiveness of therapeutic drug regimens within minutes. Not only that, but there are also various PS-MS tests in development for rapidly identifying microbial pathogens quickly and easily, without the delay of waiting hours or days for traditional test results before starting a patient on antibiotics. The possibilities for building upon this research and finding innovative ways to solve existing problems are nearly endless.

We would like to warmly thank Trevor Glaros for sharing his research and expertise with us, and we look forward to watching for further developments in the many uses and applications of paper spray mass spectrometry.

Trevor Glaros, Ph.D. is a Principal Investigator in the BioSciences Division, BioDefense Branch, of the US Army Edgewood Chemical Biological Center in Maryland. He is an experienced researcher and classically-trained molecular biologist skilled in mass spectrometry. He received his Ph.D. in Biology from the Virginia Polytechnic Institute and State University and has done work with Virginia Tech, Frederick National Laboratory, and the Oak Ridge Institute for Science and Education before joining CCDC Chemical Biological Center. You can get in touch with Trevor at trevor.g.glaros.civ@mail.mil or connect with him on LinkedIn at https://www.linkedin.com/in/trevor-glaros-b6b961a/.

Innovative Research, Inc was established in 1998 after the realization that dependable, high-quality, and affordable research materials were hard to come by. Beginning with core products like human plasma and serum, Innovative Research, Inc has grown to be a trusted global supplier of all laboratory reagents, including human and animal biofluids, proteins, antibodies, and ELISA Kits. Today we provide top researchers and institutions with access to thousands of consistent, reliable research reagents. You can get in touch with Innovative Research at sales@innov-resarch.com, and follow us on LinkedIn at https://www.linkedin.com/company/innov-research.