Application of Laser-Induced Breakdown Spectroscopy (LIBS) for the Effective Management of Hazardous Materials Incidents

First Responders are routinely faced with the challenge of rapidly and reliably identifying unknown substances encountered in a wide range of field conditions. An extensive array of field tests and portable instrumentation have been developed and/or adapted for the purpose of detecting the presence of substances commonly encountered during First Responder operations including:

• chemical, biological, radiological, nuclear, or explosive (CBRNE) threats

• toxic industrial materials (TIM’s)• pharmaceuticals• illegal drugs• benign substances (e.g., harmless white powders)

Laser-induced breakdown spectroscopy (LIBS) is a sensor technology that could allow First Responders to manage hazardous materials incidents more efficiently, effectively, and economically than previously possible using multiple pieces of equipment. The technique provides nearly instantaneous elemental analysis of solids, liquids and gases, does not require any sample preparation, and is amenable for use as a robust, man-portable device in the field in either stand-off or stand-near modes. LIBS utilizes a broadband spectrometer to collect the light emitted by a microplasma which is formed when a pulsed laser is used to interrogate a target. The data obtained can be subjected to chemometric analysis and comparison against a spectral library. This will facilitate rapid identification of the material and provides the First Responder with the information vital for making crucial decisions in a timely manner.

LIBS systems that are designed specifically for use by the First Responder community are currently under development. This presentation will explore some of the issues related to the development of suitable instrumentation and spectral libraries, as well as incorporation of the technique into existing First Responder protocols.

Adam L. Miller, Director, Huntingdon County Emergency Management Agency, Huntingdon, PA 16652, USARichard R. Hark, Department of Chemistry, Juniata College, Huntingdon, PA 16652, USA

A comprehensive response to an unknown hazard requires the First Responder to don protective apparel that is appropriate for the threat, up to and including level A vapor / flash fire combination protective suits, and carry all tools and instruments necessary to identify / classify the threat from the unknown material.

A variety of sensory and analytical instruments are needed to assess a hazard and operate in a hazardous environment. Other than standard tools for access and mitigation, a typical reconnaissance mission for the responder would require the following instruments to properly assess a hazard and protect the responders (examples shown in Figure 2):

• multi-gas meter (containing sensors for the lower explosive limit of combustible vapors, oxygen content in atmosphere by percentage, carbon monoxide content in atmosphere by ppm, and other toxic gas sensors)

• photo-ionization detector (PID)• radiation detector (varies)• vapor (and liquid if applicable)

identification / classification strips• specialty detection / classification

instruments for specific threats as anticipated (e.g. ion-mobility spectrometers for explosives, Raman spectrometers for liquid mixtures, etc.)

• sample collection / storage containers• audio/visual documentation / transmission

equipment.

Figure 2. Examples of First Responder sampling and monitoring equipment used for first-response operations at hazardous materials incidents.

Figure 4. A3 Technologies Man Portable LIBS/Raman instrument being fielded by a responder in a Level A Vapor Protective Suit.

Figure 3. A hazardous materials emergency involving fire and freight railcars..

Introduction

Today’s First Responder Environment

First Responders must be able to quickly and correctly assess the nature and magnitude of risk from an unknown substance in a field response environment. In order to accomplish this mission, responders must raise funds to purchase a wide variety of analytical equipment to address threats in each of the CBRNE categories, as well as TIM‘s and non-hazardous materials. The cost burden to accomplish this task is significant.

Figure 1. Responders working at a decontamination line.

LIBS and Tomorrow’s First Responder Environment

First Responders need to increase the efficiency of a materials recognition and identification mission. The concept of reducing the volume of instruments used to gather needed information by crossing disciplinary boundaries of detection instruments holds great interest in the First Responder market.

With so many instruments needed to be operated and transported using chemical protective clothing (shown below) there is a marked need for a technology (such as LIBS) which can be used to identify materials in all of the CBRNE, TIM and other related threat categories without adding to the physical response burden of the responder.

Responders must gather information quickly in dynamic and threatening environments; within which threats in many hazard classes exist. LIBS has the demonstrated potential to effectively assist responders identify threats, and rule out benign materials as non-threatening, in each and every hazard category that they encounter. LIBS promises swift and accurate determination of threat to the trace level, expanding the capabilities of any first response organization exponentially while providing a potential platform to reduce the number and type of instruments required to obtain needed information for hazard identification. Key areas of developmental concern are the need for robust, uniform libraries in all hazard classes, ergonomic compatibility and decontamination readiness. Units with complementary identification techniques (e.g., the LIBS / Raman unit shown in Figure 4) are also being developed.