Development of LIBS quality soils indicators for explosives contamination: initial results

TORO CINTHYA; MARTORELLA EVANGELINA; ALVIRA, F. C.; RINALDI CARLOS

Congreso; LIBS2020; 2020

Energetic materials,like explosives are often associated with armed conflicts, and do not usuallytalk about the long-term effects of these toxic compounds on the environmentdue to their manufacturing and disposal process, both for the armed forces andsecurity and for its use in mining. Nevertheless, the explosives present in thesoils are toxic compounds; TNT and RDX are classified by the United StatesEnvironmental Protection Agency (EPA) as a possible Carcinogen (for humans) andtoxic to all tested organisms and difficult degradation in the environment [1].In certain contexts in which the subject is brought to public knowledge, theyexist not only for monitoring but also for specific remediation solutions inseveral countries, such as the US, and the European community or in Argentina(Demilitarization Plan currently carried out by CITEDEF). Explosives aregenerally rich in nitro molecules and present remarkably similar spectralprofiles with emission lines between which nitrogen, carbon, hydrogen, andoxygen are used. In these cases, advanced chemometric analysis can be used forexplosive discrimination [2, 3].On the other hand,the LIBS technique has been used to characterize different types of soils thatis suitable for the qualitative analysis of heavy metals in solid samples,including environmental ones [3, 4]. The choice of this method to developed soilsquality indicators in general, and contaminated in particular, is mainly due tothe benefits presented, such as: rapid analysis, no sample preparation, portability,remote detection, the elements of high and low atomic number can be detectedsimultaneously [3-6]. Nevertheless, LIBS, as it is the case for anyspectroscopic technique, is strongly influenced by the signal fluctuations. Inthis sense, the application and combination of multivariate chemometric methodsto LIBS data sets has allowed the extraction of information and has been usedsuccessfully to identify them in metal matrices [7-8] but remains as an openquestion. In this work willbe presented results of measurements with LIBS of energetic materials (EM) inmetal matrices and in soils with the objective of finding soil qualityindicators with a LIBS instrument using the picks of Ca and Zn. To develop thequality indicators with LIBS technology, the spectrum of the calibration patterns(in different matrix) will be showed and discussed. The possibility ofidentifying EM from their matrix, the first achievement to accomplish theintent for finding soil quality indicators with LIBS instrumentation, encourageto us to continue our investigation on detection limits lowering concentration,too.