Laser-induced Breakdown Spectroscopy Measurements Research Articles

Laser-induced breakdown spectroscopy and optical microscopy investigations of crowns on the Pietà from the parish church in Skrzatusz, Poland

Research into two crowns from the Pietà in the parish church in Skrzatusz, Poland, is presented. The aim was to authenticate the individual elements from these crowns and to investigate their composition. Laser-induced breakdown spectroscopy (LIBS), optical microscopy, and multivariate analysis were used. In the first half of the seventeenth century, open crowns were typical for the first Piastowski royal dynasty in Poland. In the following two centuries, specific flower-like bows, decorative finials, and precious stones in settings were added to the crowns. LIBS showed that the crowns were made of very thickly gilded silver. Stratigraphic distributions of alloy elements were determined for all structural components. Some differences between the concentrations of elements in distinct components were confirmed, while optical microscopy demonstrated the small craters caused by the LIBS measurements. Our results confirmed data obtained earlier by art historians, and helped to authenticate the crowns.

Development of an Automated LIBS Analytical Test System Integrated with Component Control and Spectrum Analysis Capabilities**supported by the National Major Scientific Instruments and Equipment Development Special Funds of China (No. 2011YQ030113)

The present paper proposes an automated Laser-Induced Breakdown Spectroscopy (LIBS) analytical test system, which consists of a LIBS measurement and control platform based on a modular design concept, and a LIBS qualitative spectrum analysis software and is developed in C#. The platform provides flexible interfacing and automated control; it is compatible with different manufacturer component models and is constructed in modularized form for easy expandability. During peak identification, a more robust peak identification method with improved stability in peak identification has been achieved by applying additional smoothing on the slope obtained by calculation before peak identification. For the purpose of element identification, an improved main lines analysis method, which detects all elements on the spectral peak to avoid omission of certain elements without strong spectral lines, is applied to element identification in the tested LIBS samples. This method also increases the identification speed. In this paper, actual applications have been carried out. According to tests, the analytical test system is compatible with components of various models made by different manufacturers. It can automatically control components to get experimental data and conduct filtering, peak identification and qualitative analysis, etc. on spectral data.

Laser-induced breakdown spectroscopy: Extending its application to soil pH measurements

Acid–base equilibria are involved in almost all the processes that occur in soil. The bioavailability of nutrients for plants, for instance, depends on the solubilization of mineral nutrients in the soil solution, which is a pH-dependent process. The determination of pH in soil solutions is usually carried out by potentiometry using a glass membrane electrode, after extracting some of the soil components with water or CaCl2 solution. The present work describes a simple method for determining the pH of soil, using laser-induced breakdown spectroscopy (LIBS). Sixty samples presenting different textural composition and pH (previously determined by potentiometry) were employed. The samples were divided into a calibration set with fifty samples and a validation set with ten samples. LIBS spectra were recorded for each pelleted sample using laser pulse energy of 115mJ. The intensities of thirty-two emission lines for Al, Ca, H, and O were used to fit a partial least squares (PLS) model. The model was validated by prediction of the pH of the validation set samples, which showed good agreement with the reference values. The prediction mean absolute error was 0.3 pH units and the root mean square error of the prediction was 0.4. These results highlight the potential of LIBS for use in other applications beyond elemental composition determinations. For soil analysis, the proposed method offers the possibility of determining pH, in addition to nutrients and contaminants, using a single LIBS measurement.

Direct determination of Ti content in sunscreens with laser-induced breakdown spectroscopy: Line selection method for high TiO2 nanoparticle concentration

Sunscreen represents a large variety of creams which, in the analytical point of view, exhibit a similar matrix. Such matrix corresponds to a semi-solid emulsion of mixture of oil and water. The formulation of a cream can include metal and nonmetal elements in different contents in order to realize specific pharmaceutical or cosmetic functions designed for the product. The complex matrix of these materials makes their analysis challenging for classical elemental analytical techniques with specific and complicated sample pretreatment procedures needed for reliable quantification. In this work we demonstrate and assess direct determination, without any pretreatment, of elemental content, especially for metallic element such as titanium, in a sunscreen using laser-induced breakdown spectroscopy (LIBS). The used configuration corresponds to that of indirect ablation of a thin film of cream applied on the surface of a pure aluminum target. We especially focused, in this work, on the case of high concentration of TiO2 nanoparticle in cream. Such choice was justified first by the fact that such concentration level is usually found in commercial sunscreens. On the other hand, titanium presents a large number of lines, neutral as well as singly ionized, in the spectral range from the near UV to the near IR. It provides therefore an ideal case to study line selection method to manage the effect of self-absorption, which becomes unavoidable at high concentration level, and to optimize measurement precision. Through such study, we try to deduce a quantifiable and generalizable line selection method for high performance LIBS measurements. More specifically, calibration curves were first established using 6 laboratory-prepared samples. The quadratic term of the curves was then studied as a function of the intensity of the used lines and their type (neutral or ion, resonant or non-resonant). The prediction performance of the lines was assessed with 2 validation samples with relatively low Ti content for one and higher Ti content for the second. The titanium content of 4 unknown samples was finally determined using a set of different selected lines.

Double pulse Laser Induced Breakdown Spectroscopy measurements on ITER-like samples

Laser Induced Breakdown Spectroscopy (LIBS) is an attractive analytical technique for the in situ analysis of the chemical composition of the components inside the vacuum vessel of ITER and for estimating the tritium content in the machine. To improve its sensitivity a dual pulse (DP) configuration, with two laser pulses delayed in the range of nanosecond to several microseconds can be used.In this work DP measurements carried out jointly by ENEA and IPPLM associations in the frame of EFDA task WP13-IPH-A01-P3-01 on samples resembling ITER in vessel components after material re-deposition (still including carbon) are presented. A DP Nd:YAG laser, operating at 1064nm, with delay between pulses ranging from 20ns to 80ms and pulse duration of 8–12ns was used to interact with tungsten sample coated with 3μm thick mixed layer of C/Al/W (Al was used instead of Be).An enhancement of the spectroscopic emission of the elements was observed compared to the standard LIBS measurements. A Calibration Free method was applied to the data for getting the concentration of each element. Results are in good agreement with the concentrations found by the post-mortem energy dispersive X-ray (EDX) analysis.

Influence of Flame Emission Spectroscopy on K measurement Using Laser Induced Breakdown Spectroscopy

During the combustion of coal or biomass, the inherent alkali metals in the fuel will be released to the gas phase. The released alkali species condensed during the cooling of the flue gas, which may subsequently cause problems with ash deposition and corrosion in thermal fuel conversion systems. Laser Induced Breakdown Spectroscopy (LIBS) is an effective technique to measure the alkali species in the plume of burning coal or biomass. In this study, an LIBS experimental system with a flat flame burner was set up, and the Flame Emission Spectroscopy (FES) and LIBS of K in the flat flame environment were measured using different ICCD gate-width times. The experimental results revealed that with the same ICCD gate-width time, the LIBS intensity of K was higher than the FES intensity of K in the flat flame. With the increase of the ICCD gate-width time, both intensities increased, but their increase rates were different: the increase rate of the LIBS intensity of K was firstly fast then became slow, but the increase rate of the FES intensity of K was constant. Furthermore, the intensity ratio of LIBS to FES of K increased monotonically with the ICCD gate-width time in the range of 0-8 µs, until reaching approximately 4. Then, further increasing the ICCD gate-width time, such ratio decreased slowly with an asymptote value of 1. After analyzing the influences of the FES on the LIBS measurement of K in a flame condition, it is proposed that to minimize such influence, the optimization of the ICCD gate-width time was necessary, which maximized the intensity ratio of LIBS to FES-of K and facilitated the measurement accuracy of K in the flame environment using LIBS.

Overview of the FTU results

Since the 2012 IAEA-FEC Conference, FTU operations have been largely devoted to runaway electrons generation and control, to the exploitation of the 140 GHz electron cyclotron (EC) system and to liquid metal limiter elements. Experiments on runaway electrons have shown that the measured threshold electric field for their generation is larger than predicted by collisional theory and can be justified considering synchrotron radiation losses. A new runaway electrons control algorithm was developed and tested in presence of a runaway current plateau, allowing to minimize the interactions with plasma facing components and safely shut down the discharges. The experimental sessions with 140 GHz EC system have been mainly devoted to experiments on real-time control of magnetohydrodynamic (MHD) instabilities using the new EC launcher with fast steering capability. Experiments with central EC injection have shown the onset of 3/2 and 2/1 tearing modes, while EC assisted breakdown experiments have been focused on ITER start-up issues, exploring the polarization conversion at reflection from inner wall and the capability to assure plasma start-up even in presence of a large stray magnetic field. A new actively cooled lithium limiter has been installed and tested. The lithium limiter was inserted in the scrape-off layer, without any damage to the limiter surface. First elongated FTU plasmas with EC additional heating were obtained with the new cooled limiter. Density peaking and controlled MHD activity driven by neon injection were investigated at different plasma parameters. A full real-time algorithm for disruption prediction, based on MHD activity signals from Mirnov coils, was developed exploiting a large database of disruptions. Reciprocating Langmuir probes were used to measure the heat flux e-folding length in the scrape-off layer, with the plasma kept to lay on thea internal limiter to resemble the ITER start-up phase. New diagnostics were successfully installed and tested, as a diamond probe to detect Cherenkov radiation produced by fast electrons and a gamma camera for runaway electrons studies. Laser induced breakdown spectroscopy measurements were performed under vacuum and with toroidal magnetic field, so demonstrating their capability to provide useful information on the surface elemental composition and fuel retention in present and future tokamaks, such as ITER.

Detection and Identification of Amino Acids in Ficoll Solutions with Femtosecond Laser-Induced Breakdown Spectroscopy

We report femtosecond Laser-induced Breakdown Spectroscopy (fs-LIBS) measurements on several amino acids (Serine, Glutamine, and Cysteine) and Albumin protein solutions mixed with ficoll at different concentrations. The goal is to assess the effects of a host matrix on the identification and spectral characterization of amino acids by fs-LIBS. fs-LIBS utilizes an intense short laser pulse to obliterate a sample into basic constituents and to record the emission spectrum of atoms, ions, and molecules in the cooling down of the plasma plume. Several spectral peaks associated primarily with elemental composition of a sample were observed in the fs-LIBS spectra in a range from 200 to 950 nm. In addition, some molecular information associated with diatomic vibrational modes in certain molecules such as C-C and C-N were also obtained. The presence of ficoll affects the relative intensity and broadening of the C-N band, which is a signature of the amino acids. The influence of ambient gas on the fs-LIBS measurements was also analyzed under helium and argon environments, and a different behavior of peaks associated with He and Ar as a function of amino acids and ficoll mixture composition was observed. The fs-LIBS data and their analysis compare favorably with those derived from Fourier Transform Infrared Spectroscopy (FTIR). Interpretation of the spectral information enclosed in the emission of the diatomic molecules during laser ablation may lead to a better understanding of plume chemistry with a direct consequence on chemical analysis of complex samples such as amino acids. Altogether, the results demonstrate the potential of fs-LIBS technique as a detection method of biomolecules and for probing interactions of these biomolecules with a host matrix.

Pasture Vegetation Elemental Analysis by Laser-Induced Breakdown Spectroscopy

Laser-induced breakdown spectroscopy (LIBS) is a new technique for the analysis of plant material. This study investigates the application of LIBS to pasture-based plant samples. The LIBS measurements were obtained from pelletized pasture samples (100 samples) that had been also analyzed by inductively coupled plasma–optical emission spectroscopy (ICP-OES) following microwave digestion for calibration and comparison purposes. Comparisons for elements sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), boron (B), phosphorus (P), and sulfur (S) showed that LIBS could be used for almost all the standard profile total elements with concentrations down to low mg/kg levels (observed error of Na: 0.024 percent, K: 0.18 percent, Mg: 0.016 percent, Ca: 0.073 percent, P: 0.017 percent, Mn: 31 mg/kg, Fe: 150 mg/kg, Zn: 6.6 mg/kg, and B: 1.1 mg/kg). Elemental analysis at less than mg/kg levels was not possible using LIBS. The elements S and Cu were particularly difficult to analyze with reliability using LIBS at the concentration levels found in the plant samples. Replacing microwave digestion and subsequent ICP analysis with a direct analysis of dried plant samples using LIBS has the potential to improve the productivity and reduce the cost of testing.

Time-resolved aluminium laser-induced plasma temperature measurements

We seek to characterize the temperature decay of laser-induced plasma near the surface of an aluminium target from laser-induced breakdown spectroscopy measurements of aluminium alloy sample. Laser-induced plasma are initiated by tightly focussing 1064 nm, nanosecond pulsed Nd:YAG laser radiation. Temperatures are inferred from aluminium monoxide spectra viewed at systematically varied time delays by comparing experimental spectra to theoretical calculations with a Nelder Mead algorithm. The temperatures are found to decay from 5173 ± 270 to 3862 ± 46 Kelvin from 10 to 100 μs time delays following optical breakdown. The temperature profile along the plasma height is also inferred from spatially resolved spectral measurements and the electron number density is inferred from Stark broadened Hβ spectra.

LIBS analysis of tungsten coatings exposed to Magnum PSI ELM-like plasma

The aim of this work was to study the applicability of laser induced breakdown spectroscopy (LIBS) as an in situ method for monitoring plasma facing materials in fusion reactors. Tungsten coated samples were exposed to Magnum PSI plasma using two different regimes: the steady-state (the sequence of approximately 11s pulses) and the ELM-like. Right after the plasma exposure samples were tested with LIBS in the Magnum PSI analyses and target exchange chamber.Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used to characterize the surface morphology and crystallinity. These methods showed that changes at the sample surface caused by used ELM-like mode did not differ remarkably from those caused by steady-state mode. Surface temperature had significant effect on the surface structure. In addition post mortem LIBS measurements were performed that gave result similar to that of in situ LIBS.

Investigation of Pb in Gannan Navel Orange with Contaminant in Controlled Conditions by Laser-Induced Breakdown Spectroscopy

Single-pulse laser-induced breakdown spectroscopy (LIBS) was applied at natural atmosphere for proving its feasibility of determining heavy metals in Gannan Navel orange fruits treated with contaminant in controlled lab conditions. The characteristic spectral line Pb I 405.78 nm was selected, and the LIBS experimental conditions (mainly the laser energy and delay time) were optimized in order to acquire better spectral quality in the measured spectra of orange peels. The conventional elemental analysis technique, atomic absorption spectrometry (AAS), was used to investigate the real concentration of orange peels samples. The results of AAS analysis provided better accuracy and precision compared with LIBS. A calibration curve of the LIBS intensity vs AAS concentration of Pb element was constructed. Quantitative analytical results obtained by the curve were validated with AAS measurements. The presented results showed that standard deviations of the LIBS measurements are in general much larger than those of AAS measurements. Mostly, this was due to the matrix effect of samples and instability of LIBS. The agreement between LIBS and AAS demonstrates the ability of LIBS to determine the concentration of Pb in oranges.

Temporal release of potassium from pinewood particles during combustion

The temporal release of K from single pinewood particles of four different initial masses (20–50mg) in a Hencken burner was measured in-situ by laser-induced break down spectroscopy (LIBS). Particle temperature during the combustion was measured by two-color pyrometry. A calculation method was developed to determine the K release flux across the plume based on LIBS measurement and computational fluid dynamics (CFD) model. For all the 4 particle sizes, the temporal release rate of K showed a peak during devolatilization, a monotonous increase during char combustion and a monotonous decrease during the ash stage. It is found that the cumulative fraction of released K was below 4% in the devolatilization stage and ∼20% in the char combustion stage. The particle mass did not have significant influence on the K release. The mechanism of the K release during the char combustion was analyzed, based on the initial portioning of K as inorganic K and organically-bound Char-K. The inorganic K releases mainly by thermal decomposition. The Char-K releases mainly by converting first to inorganic K when the char is burnt and then by releasing to gas phase from the inorganic K. A kinetic model for the release of K during pinewood char combustion was developed on this basis. The kinetic parameters for the release of K was found to be influenced by the initial partitioning between the inorganic K and the Char-K. The correlated initial proportion of inorganic K in pinewood char was found to be 0.37, while the correlated pre-exponential factor and the activation energy for K release were 12.51/s and 89.9kJ/mol, respectively.

Sensitive detection of chlorine in iron oxide by single pulse and dual pulse laser-induced breakdown spectroscopy

The halogen chlorine is hard to detect in laser-induced breakdown spectroscopy (LIBS) mainly due to its high excited state energies of 9.2 and 10.4eV for the most intense emission lines at 134.72nm and 837.59nm, respectively. We report on sensitive detection of Cl in industrial iron oxide Fe2O3 powder by single-pulse (SP) and dual-pulse (DP) LIBS measurements in the near infrared range in air. In compacted powder measured by SP excitation (Nd:YAG laser, 532nm) Cl was detected with limit of detection LOD=440ppm and limit of quantitation LOQ=720ppm. Orthogonal DP LIBS was studied on pressed Fe2O3 pellets and Fe3O4 ceramics. The transmission of laser-induced plasma for orthogonal Nd:YAG 1064nm and ArF 193nm laser pulses showed a significant dependence on interpulse delay time (ipd) and laser wavelength (λL). The UV pulses (λL=193nm) were moderately absorbed in the plasma and the Cl I emission line intensity was enhanced while IR pulses (λL=1064nm) were not absorbed and Cl signals were not enhanced at ipd=3μs. The UV laser enhancement of Cl signals is attributed to the much higher signal/background ratio for orthogonal DP excitation compared to SP excitation and to the increased plasma temperature and electron number density. This enabled measurement at a very short delay time of td≥0.1μs with respect to the re-excitation pulse and detection of the very rapidly decaying Cl emission with higher efficiency.

Laser-induced breakdown spectroscopy for in situ qualitative and quantitative analysis of mineral ores

In this work, the potential of laser-induced breakdown spectroscopy (LIBS) for discrimination and analysis of geological materials was examined. The research was focused on classification of mineral ores using their LIBS spectra prior to quantitative determination of copper. Quantitative analysis is not a trivial task in LIBS measurement because intensities of emission lines in laser-induced plasmas (LIP) are strongly affected by the sample matrix (matrix effect). To circumvent this effect, typically matrix-matched standards are used to obtain matrix-dependent calibration curves. If the sample set consists of a mixture of different matrices, even in this approach, the corresponding matrix has to be known prior to the downstream data analysis. For this categorization, the multielemental character of LIBS spectra can be of help. In this contribution, a principal component analysis (PCA) was employed on the measured data set to discriminate individual rocks as individual matrices against each other according to their overall elemental composition. Twenty-seven igneous rock samples were analyzed in the form of fine dust, classified and subsequently quantitatively analyzed. Two different LIBS setups in two laboratories were used to prove the reproducibility of classification and quantification. A superposition of partial calibration plots constructed from the individual clustered data displayed a large improvement in precision and accuracy compared to the calibration plot constructed from all ore samples. The classification of mineral samples with complex matrices can thus be recommended prior to LIBS system calibration and quantitative analysis.

LIBS measurements and numerical studies of potassium release during biomass gasification

This paper reports on a joint numerical and experimental investigation of the release of potassium from biomass during gasification process. In this work, laser-induced breakdown spectroscopy (LIBS) was adopted to measure quantitatively the concentration of potassium from gasifying biomass. The effect of temperature on the potassium release is investigated in hot gas mixture of CO2, H2O with different concentration of O2. A biomass thermochemical conversion model is employed to study the physical and chemical processes inside the particle. A sub-model is developed to simulate the various stages of potassium release during biomass conversion and to improve the chemical kinetic mechanism and chemical kinetic constants of the release rate. Two stages of the potassium release associated to devolatilization and char reaction and ash-cooking stages are proposed. The rate of release of potassium during char reaction and ash-cooking stages follows a first order Arrhenius expression as 2.5×105±0.2exp(-266×103/RT). The kinetics rate constants along with the reaction path appear to be able to predict the potassium release with an acceptable accuracy.

Ab-initio modeling of an iron laser-induced plasma: Comparison between theoretical and experimental atomic emission spectra

We report on efforts to model the Fe emission spectrum generated from laser-induced breakdown spectroscopy (LIBS) measurements on samples of pure iron oxide (Fe2O3). Our modeling efforts consist of several components. We begin with ab-initio atomic structure calculations performed by solving the Hartree–Fock equations for the neutral and singly ionized stages of Fe. Our energy levels are then adjusted to their experimentally known values. The atomic transition probabilities and atomic collision quantities are also computed in an ab-initio manner. We perform LTE or non-LTE calculations that generate level populations and, subsequently, an emission spectrum for the iron plasma for a range of electron temperatures and electron densities. Such calculations are then compared to the experimental spectrum. We regard our work as a preliminary modeling effort that ultimately strives towards the modeling of emission spectra from even more complex samples where less atomic data are available.

Correcting for variable laser-target distances of laser-induced breakdown spectroscopy measurements with ChemCam using emission lines of Martian dust spectra

As part of the Mars Science Laboratory, the ChemCam instrument acquires remote laser induced breakdown spectra at distances that vary between 1.56m and 7m. This variation in distance affects the intensities of the measured LIBS emission lines in non-trivial ways. To determine the behavior of a LIBS emission line with distance, it is necessary to separate the effects of many parameters such as laser energy, laser spot size, target homogeneity, and optical collection efficiency. These parameters may be controlled in a laboratory on Earth but for field applications or in space this is a challenge. In this paper, we show that carefully selected ChemCam LIBS emission lines acquired from the Martian dust can be used to build an internal proxy spectroscopic standard. This in turn, allows for a direct measurement of the effects of the distance of various LIBS emission lines and hence can be used to correct ChemCam LIBS spectra for distance variations. When tested on pre-launch LIBS calibration data acquired under Martian-like conditions and with controlled and well-calibrated targets, this approach yields much improved agreement between targets observed at various distances. This work lays the foundation for future implementation of automated routines to correct ChemCam spectra for differences caused by variable distance.

Monitoring of heavy metal particle emission in the exhaust duct of a foundry using LIBS

Heavy metals have long been known to be detrimental to human health and the environment. Their emission is mainly considered to occur via the atmospheric route. Most of airborne heavy metals are of anthropogenic origin and produced through combustion processes at industrial sites such as incinerators and foundries. Current regulations impose threshold limits on heavy metal emissions. The reference method currently implemented for quantitative measurements at exhaust stacks consists of on-site sampling of heavy metals on filters for the particulate phase (the most prominent and only fraction considered in this study) prior to subsequent laboratory analysis. Results are therefore known only a few days after sampling. Stiffer regulations require the development of adapted tools allowing automatic, on-site or even in-situ measurements with temporal resolutions. The Laser-Induced Breakdown Spectroscopy (LIBS) technique was deemed as a potential candidate to meet these requirements.On site experiments were run by melting copper bars and monitoring emission of this element in an exhaust duct at a pilot-scale furnace in a French research center dedicated to metal casting. Two approaches designated as indirect and direct analysis were broached in these experiments. The former corresponds to filter enrichment prior to subsequent LIBS interrogation whereas the latter entails laser focusing right through the aerosol for detection. On-site calibration curves were built and compared with those obtained at laboratory scale in order to investigate possible matrix and analyte effects. Eventually, the obtained results in terms of detection limits and quantitative temporal monitoring of copper emission clearly emphasize the potentialities of the direct LIBS measurements.

Quantification of total carbon in soil using laser-induced breakdown spectroscopy: a method to correct interference lines.

The C cycle in the Brazilian forests is very important, mainly for issues addressed to climate changes and soil management. Assessing and understanding C dynamics in Amazonian soils can help scientists to improve models and anticipate scenarios. New methods that allow soil C measurements in situ are a crucial approach for this kind of region, due to the costs for collecting and sending soil samples from the rainforest to the laboratory. Laser-induced breakdown spectroscopy (LIBS) is a multielemental atomic emission spectroscopy technique that employs a highly energetic laser pulse for plasma production and requires neither sample preparation nor the use of reagents. As LIBS takes less than 10 s per sample measurement, it is considered a promising technique for in situ soil analyses. One of the limitations of portable LIBS systems, however, is the common overlap of the emission lines that cannot be spectrally resolved. In this study a method was developed capable of separating the Al interference from the C emission line in LIBS measurements. Two typical forest Brazilian soils rich in Al were investigated: a spodosol (Amazon Forest) and an oxisol (Atlantic Forest). Fifty-three samples were collected and analyzed using a low-resolution LIBS apparatus to measure the intensities of C lines. In particular, two C lines were evaluated, at 193.03 and 247.86 nm. The line at 247.86 nm showed very strong interference with Fe and Si lines, which made quantitative analysis difficult. The line at 193.03 nm showed interference with atomic and ionic Al emission lines, but this problem could be solved by applying a correction method that was proposed and tested in this work. The line at 247.86 was used to assess the proposed model. The strong correlation (Pearson's coefficient R=0.91) found between the LIBS values and those obtained by a reference technique (dry combustion by an elemental analyzer) supported the validity of the proposed method.