Laser-Induced Breakdown Spectroscopy: A Closer Look at the Capabilities of LIBS, Part II

In part I of this interview (1), Dr. Richard R. Hark, a professor in the Department of Chemistry at Juniata College in Huntingdon, Pennsylvania, discussed his work with laser-induced breakdown spectroscopy (LIBS) in applications such as forensic science, conflict minerals, and geochemical fingerprinting. Here, Hark discusses his work using LIBS for emergency response to hazardous materials. We also spoke with Adam L. Miller, the director at the Huntingdon County Emergency Management Agency in Pennsylvania, about his work as a first responder and how he has been involved in Hark's research.

Your research has led you to work with emergency management teams such as the Huntingdon County Emergency Management Agency (EMA). How did you get involved in this area of LIBS research?

Hark: I was trained as a hazardous materials technician and have served as a volunteer with the Huntingdon County EMA for more than a decade. After I acquired a LIBS instrument, I recognized that this technique offered many significant benefits that could make it a valuable tool for hazmat operations. Through my association with the Army Research Laboratory (ARL), I became involved in a project to make this technology available to military and civilian first responders. I recommended that our EMA director, Adam Miller, join the project team and the two of us have been collaborating on the development of LIBS-based tools since that time.

In what ways can you apply LIBS to help in emergency situations?

Hark: First responders routinely need to rapidly and reliably distinguish genuine chemical, biological, radiological, nuclear, or explosive (CBRNE) threats from benign substances (for example, harmless white powders) in a wide range of field conditions. LIBS is a technique that can be configured as a field-portable standoff or close-contact instrument that requires no sample preparation, consumes only small amounts of material, and offers high-throughput analysis. The development of suitable LIBS instrumentation and useful spectral libraries of common hazards combined with chemometric processing of data in real time gives this approach several distinct advantages over existing methodology.

Have you been involved in real-world emergency situations in which LIBS was needed?

Hark: There have been multiple times when it would have been ideal to have a portable LIBS tool when presented with the need to identify an unknown substance quickly. However, such an instrument specifically designed for first responders is not yet commercially available. I have used a laboratory-based LIBS system to analyze materials collected from a hazmat scene, but only after the fact, to confirm an on-site assessment.

How will LIBS help first responders in the future? Do you expect the new handheld instruments to be a major breakthrough for this application of LIBS?

Hark: When first responders arrive at the scene of a hazmat incident they must quickly, yet safely, determine the threat level associated with the situation. To do this, they typically utilize several pieces of testing equipment that may have to be carried into the hot zone and operated while the responder is wearing restrictive personal protective equipment such as a Level A suit and a self-contained breathing apparatus (SCBA). If a single handheld LIBS unit could replace multiple pieces of gear and be amenable for use in harsh environments, it could serve as a real boon to hazmat operations.

LIBS: A First Responder's Perspective

Adam Miller gave us his perspective on how LIBS is being used by first responders and the potential for this technique in the future.

You have been a first responder for many years. What made you want to get involved in the scientific or research aspect of your field?

Miller: Since childhood, I have immersed myself in science and had an early background in the natural sciences. While I did not choose chemistry, for example, as an education or career path, I have always been comfortable working with Hark and other colleagues on the "analytical spoke" of a hazardous materials incident investigation. Akin to many of my colleagues whose career paths intersect with responsibilities for hazardous materials incident management, there's always an inclination to seeking out the best resources available to better clear these incidents safely. In the mid-2000s, a confluence of personal and professional events allowed Hark and me to work together on advancing LIBS for emergency responders, and we have remained friends and colleagues since. My hope was that by bringing an emergency responder into the research and development phases of a response instrument's development, the delivered instrument would be a piece of equipment that was fully relevant and purpose-built around responders' needs.

How did you get involved with Professor Hark's research on LIBS?

Miller: When our agency needed to grow its human asset capabilities, Hark stepped up and trained to become a volunteer with our agency. I became a sponge, learning everything I could from Hark about what LIBS (as one of a number of technologies) could potentially do to improve our response capabilities, and as a result used what laboratory-based equipment was available to seek out more information on samples using LIBS. It was exciting to be using a technology that, at the time (and perhaps still today), many in the emergency service sector had never heard of and that holds so much promise for our future. Since we worked very well as a self-balancing team, and from our numerous dialogues with Dr. Andrzej Miziolek at ARL, we were tapped to support additional work in this field.

As a first responder, you have a unique perspective on what LIBS can do in the field. What are the main benefits you see LIBS affording to first responders? Are there any limitations for its use in this area?

Miller: We have used this technology for a number of investigations and I most enjoy the speed at which information can be acquired from a sample. There is so much to learn about materials from their elemental constituency — you can rule in or rule out a number of results or threats very quickly by knowing what is or is not present. The greatest potential, I believe, is for a mature instrument (with useful libraries and the ability to work with other established field analysis technologies) to be deployed in the hands of knowledgeable responders whose mission is best served with high quality, fast throughput, and minimal-to-no sample preparation tools. I know from our work that powder analysis, for example, can be greatly improved with LIBS as one of the data input streams to the decision calculus.

There are some major limitations that exist, but for varying reasons. For our operations, using LIBS as a class 4 laser at standoff is simply not eye safe, and few situations allow any responder to take careless actions with such a powerful instrument; during our work, however, we were constantly impressed by the excellent data we could develop on residual and trace samples at a standoff distance. Also, when the sample is too small to risk destruction, LIBS is not the right answer currently. These limitations are intrinsic; however, the most important limitations are not. The greatest limitation that exists is the lack of a reliable, transferable library of materials of interest to the emergency service sector. Until a good library exists of CBRNE threats, among other things like toxic industrial chemicals and benign materials, LIBS will not have adequate utility in our sector. Another limiting factor is a series of configurations (handheld, robotic, and so on) that meet our needs in the field. Everything depends on size, weight, ergonomics, speed, and safety. Currently, LIBS cannot meet all of our requirements. Fortunately, these are not intrinsic limitations, and with adequate investment they can be overcome.

What analytical methods are currently used in emergency situations, such as a hazardous spill? How widespread is the use of LIBS for such applications?

Miller: Reagents, atmospheric monitors, Raman spectroscopy, Fourier transform-infrared (FT-IR) spectroscopy, gas chromatography–mass spectrometry (GC–MS), and ion-mobility spectrometry (IMS) are the major fieldable technologies. There are others, but the capabilities of a given responder or agency are greatly varied. Some agencies have next to nothing (the human nose) and others (Weapons of Mass Destruction Civil Support Teams) have mobile laboratories with everything that can be mobilized. To my knowledge, except for some academic institutions that have assisted investigations from their laboratories (such as Florida International University and Juniata College), there are no fielded instruments in any emergency service today. We were the closest that I know of to getting there, and still did not achieve the desired end result.

What is the response like in the first-responder community to the idea of using LIBS?

Miller: LIBS is not really out there —still. Most responders don't even know it exists, and for the few knowledgeable ones that do, the lack of a fielded instrument on the market has not resulted in the best impressions (and those are all subjective.) The bad news: LIBS, as a story for responders, may have "hit the wire" prematurely. The good (perhaps great) news: The story didn't make the mainstream news, so there is still room to develop a great story. For those that I have discussed it with, the possibilities and potential of LIBS is tantalizing and intriguing, but results speak louder than words. When the right instrument with the right capabilities hits the market (and makes a seriously positive impact on our operational capabilities), I do believe the story will be an impressive one.

In what specific scenarios do you foresee LIBS being a major asset to a first-response team?

Miller: The area that I have the most expectation is in the regime of powder and unknown materials calls. LIBS can be used on its own, or better yet in an orthogonal configuration with other molecular analysis instruments, to develop a compelling picture of how serious a threat may exist. We make decisions every day that can mean life or death, and every quality data point is worth considering in the decision matrix — especially from the analytical instruments we have in the field. The faster we can make a good decision, the better the odds that impact, injury, or death will be minimized. I foresee LIBS adding to the tools in our toolbox to more rapidly come to a presumptive (or confirmatory in some cases) conclusion that supports an incident commander in making a decision. From my experience, trace analysis of explosives (for security threat screening), powders and materials screening (drugs versus explosives versus benign), and identifying spread of threat (area and stratigraphic sampling) are some of the best applications for the emergency response sector.

Have you used LIBS in the field for any specific emergencies?

Miller: In July 2014, interestingly, we used LIBS in the lab to help screen an unknown threat from an individual who purported to be building a gas generator to kill himself with. We were able to make a pretty interesting find that allowed law enforcement personnel to adjust their actions and address the remaining threat material left behind in an effective manner. While I cannot discuss specifics because of the active investigation, suffice it to say that LIBS provided information that allowed us to make decisions about how to safely handle a two-site emergency with greater comfort and confidence than we could have otherwise.

Is there a need for a LIBS system in every town or city in the United States? Also, is the cost of a LIBS system realistic for most towns or cities?

Miller: I constantly refuse to talk cost, much to the frustration of many I work with. The bottom line is this: If it is your job to make a decision, you need to have the tools to make that decision accessible to you. If one response agency or jurisdiction feels comfortable working with others, or is in proximity to others who can assist, then there is no need to worry about it. If you are not, then you are most likely in search of resources to do that job better. We are very rural, yet I know that the support resources available to me (if not being used by someone else) are hours away and may take some substantial politicking to get them mobilized, depending on the situation. I have been in the shoes of the person who had to make serious decisions without all of the advantages required, and I vowed that would never happen again. Having LIBS, among other excellent technologies, within reach either on our own apparatus or at Juniata College's lab is not only comforting, it's absolutely necessary to meeting my needs. I can assure you that our community's budget has no room for the technologies we have — acquiring them became a matter of partnership, barter, grant-writing, and prioritizing available resources. In the end, I believe that with enough directed effort, those who need this resource will find a way to acquire it — so long as the cost is competitive with other capabilities needed. Grants and funds are reduced compared to the past, but when a good solution is available, it seems politics will eventually catch up to it.

Aside from cost savings, what benefits do you think a handheld LIBS system would add to a first-response team?

Miller: In addition to those mentioned before, a LIBS (or more likely a LIBS-fused sensor suite) can reduce the total number of instruments fielded downrange and expedite the analysis — potentially without even directly exposing the responder to the hazardous material (by operating in a standoff, stand-near, or robotic fashion). Once this technique has matured and been vetted for forensic use, I think you will see this become an indispensable instrument for law enforcement as well.

Is there anything else you would like to add about LIBS applications for emergency responders?

Miller: I like to frame LIBS, like other emerging technologies for the emergency service sector, in this light: If your child is contaminated or at risk, how fast is fast enough — or how accurate is accurate enough — for you to make a life or death decision about the health and safety of your child? How much ambiguity will you tolerate? Is the space that was contaminated, that you work in, "safe" enough to return to? I believe LIBS will help address these concerns, among many others, better than can be done today. When it comes down to ensuring the safety of a child, or our loved ones, there is no question that work furthering promising technologies such as LIBS is justified.

References

(1) R.R. Hark, Spectroscopy 29(7), 34–37 (2014).