Development of LIBS soils quality indicators for explosives contamination

J. VOROBIOFF; N. BOGGIO; C. TORO; E. MARTORELLA; C. RINALDI; F. PEREYRA; J. CANALE; F. ALVIRA

Kyoto

Conferencia; LIBS2020 Kyoto - 11th International Conference on Laser Induced Breakdown Spectroscopy; 2020

Tokushima University

Energetic materials, like explosives are often associated with armed conflicts, and do not usually talk about the long-term effects of these toxic compounds on the environment due to their manufacturing and disposal process, both for the armed forces and security and for its use in mining. Nevertheless, the explosives present in the soils are toxic compounds; TNT and RDX are classified by the United States Environmental Protection Agency (EPA) as a possible Carcinogen (for humans) and toxic to all tested organisms and difficult degradation in the environment. In certain contexts in which the subject is brought to public knowledge, they exist not only for monitoring but also for specific remediation solutions in several countries, such as the US, and the European community or in Argentina (Demilitarization Plan currently carried out by CITEDEF). Explosives are generally rich in nitro molecules and present remarkably similar spectral profiles with emission lines between which nitrogen, carbon, hydrogen, and oxygen are used. In these cases, advanced chemometric analysis can be used for explosive discrimination.On the other hand, the LIBS technique has been used to characterize different types of soils that is suitable for the qualitative analysis of heavy metals in solid samples, including environmental ones. The choice of this method to developed soils quality indicators in general, and contaminated in particular, is mainly due to the benefits presented, such as: rapid analysis, no sample preparation, portability, remote detection, the elements of high and low atomic number can be detected simultaneously. Nevertheless, LIBS, as it is the case for any spectroscopic technique, is strongly influenced by the signal fluctuations. In this sense, the application and combination of multivariate chemometric methods to LIBS data sets has allowed the extraction of information and has been used successfully to identify them in metal matrices but remains as an open question. In this work will be presented results of measurements with LIBS of energetic materials (EM) in metal matrices and in soils with the objective of finding soil quality indicators with a LIBS instrument using the picks of Ca and Zn. To develop the quality indicators with LIBS technology, the spectrum of the calibration patterns (in different matrix) will be showed and discussed. The possibility of identifying EM from their matrix, the first achievement to accomplish the intent for finding soil quality indicators with LIBS instrumentation, encourage to us to continue our investigation on detection limits lowering concentration, too.