Leaves of yerba mate plant (Ilex paraguariensis) have a wealth of nutrients, ingested by people who drink them in the hot water infusion popularly known as mate. In the present work, the laser-induced breakdown spectroscopy (LIBS) technique was applied for the first time to analysis of the extractability of macronutrients, including Mg, Ca, Na, and K, in commercial samples of yerba mate. Powdered samples from leaves’ material were used to simulate the infusion process in the laboratory. To carry out LIBS analysis, the emission spectra were measured before and after the infusion from the samples prepared in pellets. The spectral data were processed and analyzed by a specially designed algorithm. A coefficient of extractability was calculated for each of the investigated macronutrients in the range 34–76%, showing a good correlation with the corresponding elemental concentrations leached into the water infusion, determined by Atomic Absorption Spectroscopy. The obtained results demonstrated the feasibility of our approach for the rapid analysis of extractable macronutrients present in yerba mate leaves.

In this work, a fitting algorithm was implemented and applied to analyze emission line shapes in laser-induced breakdown spectroscopy. By modeling emission spectral lines, the optical thickness was calculated for each line of interest and the intensity line profiles were computed and matched to measured spectra. The algorithm was applied to analyze the experimental profiles of a hydrogen H α line at 6562.8 Å, and the resonant lines of Mg II at 2795.5 Å and at 2802.7 Å. Spectroscopic information was obtained about the physical processes occurring in the plasma, such as self-absorption and Stark broadening. The results demonstrated the potential of the developed method to provide valuable information in plasma spectroscopy for both fundamental and applied research.

Laser–induced breakdown spectroscopy (LIBS) was applied for the rapid characterization of the elemental composition of archaeological remnants recovered from a military settlement dating from 1831, located at the center of the Argentinian Pampas (Buenos Aires province, Argentina). This research is part of an interdisciplinary project for the study of military fortifications within the field of historical archaeology. We present original results of the analysis of metallic artifacts, bones, potsherds, and colored glazed crockery of the site. The measurements included drilling through superficial weathering and corrosion layers to determine the underlying bulk composition of the materials, the analysis of glazing processes and the identification of pigments in the paintings. A new analytical approach was applied for the discrimination of elements corresponding to the pigments, the binder medium or the glaze from those belonging to the paste matrix which improved the LIBS performance. The obtained results provided useful information related to the characteristics, raw materials, manufacturing processes, use and provenance of the objects that contributed to achieve a more comprehensive knowledge of the archaeological context investigated.

En este trabajo, se realizó un análisis cuantitativo de los metales pesados Cr y Cu en sedimentos fluviales mediante espectroscopia de ruptura inducida por láser (LIBS) para evaluar el antropogénico. Para realizar el análisis, se recolectaron diferentes muestras de sedimento en las posiciones seleccionadas. Se construyeron curvas de calibración de adición estándar para Cr y Cu midiendo la línea Cr I a 357.87 nm y la línea Cu I a 324.75 nm. Los contenidos de humedad y materia orgánica de los sedimentos fueron tomados en cuenta para superar el efecto matriz. Los modelos cuantitativos se evaluaron estadísticamente para evaluar la robustez y la capacidad de predicción del método. Los valores bajos de la raíz - medias - errores cuadrados para la calibración ( RMSEC ), la predicción ( RMSEP ) y la validación cruzada (RMSECV ) se calcularon. Se obtuvieron valores altos de los coeficientes de correlación de calibración ( R 2 c = 0.984 para Cr; R 2 c = 0.986 para Cu) y validación cruzada ( R 2 cv = 0.985 para Cr; R 2 cv = 0.981 para Cu). Los límites de detección calculados ( LoD ) fueron 2.9 ppm para Cr y 3.3 ppm para Cu, y los límites de cuantificación ( LoQ) fueron 9.5 ppm para Cr y 11 ppm para Cu. Las concentraciones de Cr y Cu superiores a los valores de referencia se obtuvieron en los sedimentos aguas abajo (Cr: 49 ppm, Cu: 81 ppm) que son indicativos de la contaminación de la cuenca por metales pesados debido al derrame de efluentes no tratados derivados de actividades antropogénicas. . El análisis LIBS se optimizó para el monitoreo confiable de metales pesados en sedimentos fluviales.

Laser-induced breakdown spectroscopy (LIBS) and atomic absorption spectroscopy (AAS) techniques were applied for quantitative analysis of the remaining Pb content in water samples after treatment with a raw montmorillonite (MMT) and an organic derivative (MMO) clays for heavy metal removal, an issue of crucial importance for decontamination of water bodies. The Pb sorption capabilities of MMT and MMO clays were assessed by using solutions with known Pb concentrations, in the range 100-500 ppm. To carry out the LIBS analysis, the samples were prepared in the form of solid pellets with powdered calcium hydroxide addition. The measurement conditions were optimized to achieve reliable analytical results and the plasma parameters, i.e., temperature and electron density, were obtained. For quantification purpose, a calibration curve was constructed with the Pb I emission line at 4057.8 angstrom measured at the time window 30-45 mu s by using reference samples with Pb concentrations in the range 56-715 ppm. The Pb residual content in the liquid samples determined with LIBS showed a good agreement with those measured with AAS. The sorption efficiency of Pb from contaminated water was calculated through a sorption percentage S-pb%. The calculated S-pb% was higher for MMT (56%-100%) than for MMO (27%-47%). The results also demonstrated the usefulness of LIBS method for the determination of Pb concentrations in liquid samples.

In this paper, a generalized approach is developed and applied for plasma characterization and quantitative purposes in laser-induced breakdown spectroscopy (LIBS) experiences by employing a selected pair of spectral lines belonging to the same multiplet. It is based on the comparison between experimental ratios of line parameters and the theoretical calculus obtained under the framework of a homogeneous plasma in local thermodynamic equilibrium. The applicability of the method was illustrated by using the atomic resonance transitions 279.55–280.27nm of Mg II, which are usually detected in laser-induced plasma (LIP) during laser ablation of many kinds of targets. The laser induced plasmas were produced using a Nd:YAG laser from a pressed pellet of powdered calcium hydroxide with a concentration of 300ppm of Mg. The experimental ratios for peak intensities, total intensities and Stark widths were obtained for different time windows and matched to the theoretical calculus. The temperature and the electron density of the plasma, as well as the Mg columnar density (the atom/ion concentration times the length of the plasma along the line-of-sight), were determined. The results were interpreted under the employed approach.

In this paper, line profile analysis of several Cr transitions was carried out for characterization of a laser-induced plasma. The plasma was generated on a metallic alloy (nominal Cr concentration 29.7%) in air at atmospheric pressure by using an infrared Nd:YAG laser. The emission intensities of 24 Cr I lines and 25 Cr II lines were measured spatially integrated along the line-of-sight with good resolution. Their line profiles were analyzed applying a computational fitting algorithm under a framework of a homogeneous plasma in thermodynamic equilibrium. The effects of self-absorption and spatial inhomogeneity were taken into account. The plasma temperature and the parameters Nl (the atom/ion concentration times the length of the plasma along the line-of-sight) were accurately determined, and the electron density was estimated. The results were properly interpreted under the employed approach, demonstrating the important influence of the issues investigated on characterizing the physical state of laser-induced plasmas.

Laser-induced breakdown spectroscopy (LIBS) has been applied for quantitative analysis of Cu in algae plants, an issue of paramount importance for environmental monitoring. For the analysis with LIBS, algae were compacted into solid pellets with powdered calcium hydroxide addition as binder and a pulsed Nd:YAG laser was employed to produce the plasmas in air at atmospheric pressure. In this approach, atomic lines from traces of Cu were detected, as well as other major and minor elements. The plasma was characterized and a calibration curve was constructed with reference samples prepared with calcium hydroxide. The results obtained demonstrated the usefulness of the method for Cu monitoring in algae plants.

En el presente trabajo, la técnica Espectroscopia de plasmas producidos por láser (Laser-induced breakdown spectroscopy –LIBS–) se aplicó a la determinación cuan- titativa de Na en agua natural dulce, de interés en agricultura para el estudio de la alcalinidad de aguas de regadío. Para efectuar el análisis, se prepararon soluciones con concentraciones conocidas del analito, se mezclaron con óxido de calcio y se compactaron en pastillas sólidas. Los plasmas se produjeron en aire a presión atmos- férica utilizando un láser pulsado Nd:YAG. Se construyó una curva de calibración y se calculó el límite de detección. Se analizaron muestras de agua natural y los resultados se compararon con los obtenidos mediante espectroscopia de absorción atómica. Se demostró la factibilidad del método para la determinación de Na en agua natural dulce.

In this work, different theories for the determination of the electron density in Laser-Induced Breakdown Spectroscopy (LIBS) utilizing the emission lines belonging to the hydrogen Balmer series have been investigated. The plasmas were generated by a Nd:Yag laser (1064nm) pulsed irradiation of pure hydrogen gas at a pressure of 2·104Pa. Hα, Ηβ, Ηγ, Ηδ, and Hε Balmer lines were recorded at different delay times after the laser pulse. The plasma electron density was evaluated through the measurement of the Stark broadenings and the experimental results were compared with the predictions of three theories (the Standard Theory as developed by Kepple and Griem, the Advanced Generalized Theory by Oks et al., and the method discussed by Gigosos et al.) that are commonly employed for plasma diagnostics and that describe LIBS plasmas at different levels of approximations. A simple formula for pure hydrogen plasma in thermal equilibrium was also proposed to infer plasma electron density using the Hα line. The results obtained showed that at high hydrogen concentration, the Hα line is affected by considerable self-absorption. In this case, it is preferable to use the Hβ line for a reliable calculation of the electron density.

espanolEn el transcurso de la colaboracion entre el Departamento de Quimica y Quimica Industrial de la Universidad y el Consejo Nacional de Investigacion (CNR Consiglio Nazionale delle Ricerche), ambos en Pisa, ha sido posible analizar cientificamente diferentes muestras arqueologicas. En este caso se han seleccionado doce pequenas estatuas de bronce expuestas en el Museo Arqueologico Nacional de Crotona, que fueron previamente estudiadas, con el objetivo final de profundizar aun mas en el conocimiento de estas muestras. En el Museo Arqueologico Nacional de Crotona, fue llevado a cabo el analisis de las doce muestras de bronce basado en tecnicas espectroscopicas, concretamente LIBS (acronimo de Laser Induced Breakdown Spectroscopy), empleando el MODI (Mobile Dual-pulse Instrument, o Instrumento Movil de Doble Pulso) para analizar las muestras in situ. Las muestras obtenidas fueron analizadas cualitativamente y cuantitativamente, para discernir las caracteristicas quimicas de las muestras de bronce. El objetivo del analisis es encontrar marcadores o elementos quimicos que permitan distinguir unas muestras de otras por ser importantes en la composicion del metal que compone las estatuillas.. EnglishIn the framework of a collaboration between the Chemical and Industrial Chemical Department of the Pisa University and the National Research Council of Pisa it was possible to analyse some archaeological finds. We choose twelve little bronzes displayed at the National Archaeological Museum in Crotone, that were formerly studied. The research was performed in situ applying the LIBS technique, already used at the Museum of Reggio Calabria for the analysis of the so-called Porticello Using MODI (MObile Dual-pulse Instrument), a mobile instrument for in situ analysis, we analysed spectroscopically the twelve bronzes. The spectra obtained were analyzed both qualitatively and quantitatively to obtain the alloy composition of the bronzes. The aim of the analysis was to evidence the presence some elemental markers useful for classifying the bronzes according to the composition of the alloy.

In this paper, we investigate the self-absorption of Mg I-II emission lines on laser-induced breakdown spectroscopy (LIBS) experiments. We produced the plasmas in air at atmospheric pressure by focusing a Nd:YAG laser onto a pellet of finely powdered calcium hydroxide with a concentration of 625 ppm of Mg and recorded the intensity profiles of Mg lines at different delay times after the laser pulse from plasmas generated with different laser energies. We carried out the analysis of the line profiles within the framework of a homogeneous plasma in local thermodynamic equilibrium by a computer algorithm that calculates the emission spectra and matches them to the experimental measurements. It allowed evaluation and compensation of self-absorption by using the spectroscopic information saved on the optical thicknesses of the lines. After that, we performed the characterization of the plasma and correlated the self-absorption features with the different trends of the temperature, the electron density, and the Nl parameters obtained. At the early times of plasma evolution, we found that the fast expansion of the plume was dominant and the self-absorption effects are difficult to interpret within the current approach, supplying only qualitative information. On the other hand, at later times, the results obtained could be properly analyzed showing the practical usefulness of the method to provide valuable information for both basic and applied LIBS research.

In this paper, we discuss the application of laser-induced breakdown spectroscopy to precious metal alloys used for the control of the process of recovery and recycling of scraps and waste of industrial processes. In particular, the possibility to obtain sensitivity and trueness comparable to the current systems used in industrial environment in the quantitative determination of the elements of interest was explored. The present study demonstrates that laser-induced breakdown spectroscopy can be considered as a viable alternative to inductively coupled plasma optical emission spectrometry and X-ray fluorescence spectroscopy for the determination of recovered precious metals. The limits of detection obtained are of the order of 0.2mg/g for all the elements considered. The maximum deviation with respect to the nominal concentrations is around 1mg/g at concentrations around 20mg/g (gold) corresponding to a relative error slightly higher than ±5%.

In this paper we present the results of a study performed on a large collection of silver Roman republican denarii, encompassing about two centuries of history. The joint use of Laser-Induced Breakdown Spectroscopy (LIBS) and X-Ray Fluorescence (XRF) spectroscopy allowed for an accurate determination of the coins' elemental composition; the measurements, performed mostly in situ at the ‘Monetiere’ in Florence, revealed a striking connection between the ‘quality’ of the silver alloy and some crucial contemporary events. This finding was used to classify a group of denarii whose dating was otherwise impossible. The comparison with other contemporary denarii disproves a recent theory on the origin of the so called ‘serrated’ denarii (denarii showing notched chisel marks on the edge of the coin).

In the framework of a collaboration between the Chemical and Industrial Chemical Department of the Pisa University and the National Research Council of Pisa it was possible to analyse some archaeological finds. We choose twelve little bronzes displayed at the National Archaeological Museum in Crotone, that were formerly studied. The research was performed in situ applying the LIBS technique, already used at the Museum of Reggio Calabria for the analysis of the so-called 'Porticello bronzes'. Using MODI (MObile Dual-pulse Instrument), a mobile instrument for in situ analysis, we analysed spectroscopically the twelve bronzes. The spectra obtained were analyzed both qualitatively and quantitatively to obtain the alloy composition of the bronzes. The aim of the analysis was to evidence the presence some elemental markers useful for classifying the bronzes according to the composition of the alloy.

In this paper we report the results of a study performed with different physical and chemical methods on a ceramic vase originally attributed to the I century CE. The joint use of infrared spectroscopic analysis and laser techniques, as well as pyrolysis-gas chromatography coupled with mass spectrometry and thermoluminescence, allowed us to characterize the vase material and its content. The chemical data were combined with morphological and stylistic examinations of the object and helped in defining its actual geographical and chronological pertinence.

In this work, plasma characterization by laser-induced breakdown spectroscopy (LIBS) has been investigated. We propose a method based on the calculation of the optical thicknesses of emission spectral lines in the framework of a homogeneous optically thick plasma in local thermodynamic equilibrium (LTE). In this approach, self-absorption is taken into account to retrieve the optically thin intensities and plasma characterization is achieved. The developed procedure is applied to magnesium (Mg) lines measured from plasmas generated in air at atmospheric pressure from calcium hydroxide samples using an infrared Nd:YAG laser. The influence of laser irradiance on both plasma shape and emission intensity was studied to select the most suitable experimental conditions. Spectral lines of Mg I-II were measured and analyzed for different laser energies, delay times, and concentrations of the analyte. In each case, the plasma temperature, the electron density, and the parameters Nl were determined, without employing curves-of-growth. The results obtained showed the practical usefulness of the method to provide valuable information in LIBS experiments.

In this work, Laser-induced breakdown spectroscopy (LIBS) has been applied to characterization of plasmas generated in air at atmospheric pressure from a calcium hydroxide sample with a known concentration of Mg by using an infrared Nd:YAG laser. The influence of laser irradiance on plasma morphology and emission intensity was studied. Spatially-integrated intensities of Mg I-II lines along the line-of-sight were measured for different laser energies and delay times. The plasma temperature and the electron density were determined in each case by using and algorithm that calculates the optical thickness of the spectral lines and reproduces their experimental profiles in a framework of an homogeneous plasma in LTE that takes into account the effects of self-absorption. The results obtained showed the usefulness of this approach to provide additional information retrieved from the optical thickness of spectral lines for plasma characterization in LIBS experiments.

In the present work, the LIBS technique (Laser-Induced breakdown Spectroscopy) is addressed for its application in Mg analysis in natural water samples, an issue of interest in topics related to health, environment and agriculture. To carry out the analysis, solutions with known concentrations of the analyte were prepared, mixed with calcium oxide and compacted into solid pellets. Then, the plasmas were produced in air at atmospheric pressure by focusing a pulsed Nd:YAG laser on the surface of the samples. The spectral emission of Mg atoms and ions was studied aimed at finding the best experimental conditions for the measurements. In such optimal conditions, the plasma generated was characterized and the summed intensities of the resonance lines of Mg I at 2852.1 angstrom and of Mg II at 2795.5 angstrom were used to evaluate the analytical capabilities through a calibration curve constructed in a suitable range of concentrations. The results obtained demonstrated the feasibility of the investigated approach for quantitative determination of Mg in natural water.

espanolEn el presente trabajo la tecnica LIBS (Laser-Induced Breakdown Spectroscopy) es evaluada para su aplicacion al analisis de Mg en muestras de agua natural, el cual resulta de interes en tematicas relacionadas con la salud, el medio ambiente y la agricultura. Para efectuar el analisis, se prepararon soluciones con concentraciones conocidas del analito que fueron mezcladas con oxido de calcio y compactadas en pastillas solidas. Luego, los plasmas fueron producidos en aire a presion atmosferica enfocando un laser pulsado Nd: YAG en la superficie de las muestras. Se estudio la emision espectral de atomos e iones de Mg a fin de encontrar las mejores condiciones experimentales de medicion. En dichas condiciones optimas, se caracterizo el plasma generado y se utilizaron las intensidades sumadas de las lineas resonantes 2852.1 A de Mg I y 2795.5 A de Mg II para evaluar la capacidad analitica mediante una curva de calibracion construida en un rango adecuado de concentraciones. Los resultados obtenidos demuestran la factibilidad del procedimiento investigado para la determinacion cuantitativa de Mg en aguas naturales. EnglishIn the present work, the LIBS technique (Laser–Induced breakdown Spectroscopy) is addressed for its application in Mg analysis in natural water samples, an issue of interest in topics related to health, environment and agriculture. To carry out the analysis, solutions with known concentrations of the analyte were prepared, mixed with calcium oxide and compacted into solid pellets. Then, the plasmas were produced in air at atmospheric pressure by focusing a pulsed Nd:YAG laser on the surface of the samples. The spectral emission of Mg atoms and ions was studied aimed at finding the best experimental conditions for the measurements. In such optimal conditions, the plasma generated was characterized and the summed intensities of the resonance lines of Mg I at 2852.1 A and of Mg II at 2795.5 A were used to evaluate the analytical capabilities through a calibration curve constructed in a suitable range of concentrations. The results obtained demonstrated the feasibility of the investigated approach for quantitative determination of Mg in natural water.