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

Nov 01, 2014
By Spectroscopy Editors
Volume 29, Issue 11

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.

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