Over the last years, laser-induced breakdown spectroscopy (LIBS) has gained a very important role as a tool for in-situ cultural heritage investigations owing to its high sensibility to light elements such as H, Li, B, C, N, and O, ease of use, no need of sample pretreatment, robustness and versatility, noninvasiveness, micro- destructivity, and availability of compact transportable setups. More recently, mobile LIBS instrumentations have been developed and improved which allow the performance of trustable, contactless, fast, sensitive, multielemental analysis with a minimum impact on the art objects. In this chapter, a review is provided of the results obtained in-situ, outdoor and indoor in laboratories or museums, specifically by the use of mobile, i.e., "portable," "transportable," and handheld, LIBS instruments. In particular, LIBS applications to the analysis of monument stones, pigments, mural paintings, metal objects, coins, pottery, and jewelry are reviewed. Finally, new trends and future perspectives of LIBS as an efficient analytical tool to be extended to the analysis of even submerged materials are highlighted.

Biochar-based fertilizers are a new attractive alternative to P supplementation for crops, as they can gradually release the nutrient, avoiding losses and improving soil quality. In this regard, the evaluation of the P amount in biochar-based fertilizers is extremely important for their quality control. Analytical techniques that require sample solubilization are not very efficient for this task, as biochar is difficult to solubilize. Laser-induced breakdown spectroscopy (LIBS) is a promising technique to respond to this demand, as it enables a direct analysis of solid samples, avoiding the complicated process of sample solubilization. In this work, a novel method based on spark discharge (SD) coupled to LIBS was evaluated for P determination in biochar-based fertilizers prepared from three different biomasses. To overcome calibration problems in LIBS analysis, a matrix-matching procedure accomplished by the addition of eucalyptus biochar to calibration standards was used in experiments. This procedure minimized matrix effects and allowed us to achieve a satisfactory accuracy even when applied to similar but different matrices. Furthermore, the developed method is simple, fast, direct, does not generate post-analysis residues and appears appropriate for the quality control of sustainable biochar-based fertilizers and other biochar products.

Knowledge about the chemical composition of minerals, rocks and soils is of fundamental importance in the earth and environmental sciences (i.e. geosciences). Historically, during the late-19th and mid-20th centuries classical wet chemical analytical methods were the means of determining the elemental composition of such geological materials. Since then, intensive research in analytical inorganic chemistry has led to the development of a multiplicity of rapid and accurate instrumental analytical techniques for use in the laboratory that can be applied to elemental analysis across the periodic table. This has been of particular benefit to research in the geosciences, where the need for chemical data has continuously expanded with regard not only to the type of elements and their concentration levels, but also application to a wide variety of geological materials across the solid-liquid-gas spectrum. One of the enduring needs within the geoscience community has been the availability of analytical instrumentation capable of routine use outside the laboratory setting. Laser-induced breakdown spectroscopy (LIBS) is one of the very few current analytical technologies suitable for routine use outside the laboratory and has a persuasive set of advantages that makes it ideally suited for chemical analysis in the field. These include rapid analysis with a compact and lightweight instrument by a single individual of most types of natural materials under ambient environmental conditions in real time, and with little to no sample preparation. Although such a field analytical technique does not provide the level of elemental detection and analytical precision possible with laboratory instruments, it nevertheless provides an efficient and invaluable capability to the field investigator. To date, LIBS has been applied widely across the geosciences in sub-fields as diverse as mineralogy and petrology, volcanology, sedimentology, natural resources exploration and exploitation, pedology, and geoarchaeology.1,2 The most common applications of LIBS in the analysis of geological materials include: (i) elemental detection and identification; (ii) quantitative elemental analysis; (iii) microscale geochemical mapping; (iv) discrimination and classification of minerals and rocks of similar character via spectral matching against an assembled spectral library; and (v) determination of sample geographical origin and provenance. Although LIBS is not able to address all questions arising in geochemical research and practice due to some inherent limitations in sensitivity, it can excel for specific geoscience applications.

The main objective of this study was to provide a preliminary analysis of the meteorite North West Africa (NWA) 12606 recently classified as ureilite, which was found in 2018 in Morocco, to unveil the possible presence of diamonds. The preliminary analysis of the surface of a meteorite fragment by scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) and optical microscopy has shown that it mainly consisted of olivine, minor pyroxene and carbon phases possibly including carbon in the form of diamonds. The results achieved are preliminary to a further deeper study of this meteorite as the diamond origin in ureilites is still an open issue debated among the scientific community due to its significant implications for the sizes of early Solar System bodies.

Spark discharge (SD) laser-induced breakdown spectroscopy (LIBS) is a technique suitable to overcome the low energies of lasers by reheating the plasma, increasing the emission intensities and to perform single-standard calibration. A calibration method called one-point and multi-voltage calibration (OP-MVC), which requires two different voltages applied to both the standard and the sample, is proposed for use with SD-LIBS. The performance of this method was compared to that of the one-point and multi-lines calibration (OP-MLC) and the slope ratio calibration (SRC) methods for LIBS determination of Al in certified reference plant leaves and P in commercial fertilizers. No statistical differences at the 95% confidence level were observed between the Al and P concentrations determined by OP-MVC LIBS for the Al certified values and the P values measured by high-resolution continuum-source flame atomic absorption spectrometry (HR-CS FAAS). The limit of detection (LOD) for P was 0.60 wt% P2O5 and 35.1 mg kg(-1) for Al. The relative standard deviation (n=3) was typically 7% for Al and in the 4 - 10% range for P.

Laser-induced breakdown spectroscopy (LIBS) is a simple, straightforward, and versatile form of atomic emission spectroscopy that focuses a rapidly-pulsed laser beam onto a sample to form a plasma containing its constituent elements and then uses spectral analysis of the emitted light to detect the elements present. In theory, LIBS is capable of qualitative, semi-quantitative, and quantitative analysis of all elements in the periodic table. LIBS can be performed in the laboratory or outside in the ambient environment for on-site analysis in situ; LIBS can also be used for rapid microscale compositional imaging. This review first presents a description of the LIBS technique and then discusses and illustrates through a historic literature review how LIBS has been used to analyze gases, natural waters, minerals, rocks, sediments, and soils. Given the persistent need of analytical instrumentation for the rapid chemical analysis of geologic materials in the field, and the capability of LIBS to analyze any type of sample in real time with little to no preparation, there is a vast potential for the routine application of LIBS across a broad spectrum of the geosciences that is as yet only minimally realized.

A critical review is provided on the progress achieved in the last few years in the use of Laser-Induced Breakdown Spectroscopy (LIBS) technique in environmental system monitoring. In the first part of this review a short description of LIBS equipments, LIBS basic physical principles and supporting advanced calibration methods and chemometric approaches to LIBS analysis are provided. In the second part of the review the most recent applications of LIBS to the analysis of relevant solid, liquid and gaseous environmental systems and their contaminants, including soil, rocks, sands, sediments, eletronic wastes, waters, landfill leachates, lubricating oils and aerosols, are described. The potential and versatility of LIBS as a promising analytical tool in environmental science for in situ applications with minimal or no sample pretreatment are highlighted. The review ends with a brief conclusion and future perspectives.

In this work, the potential of single and double-pulse laser induced breakdown spectroscopy (SP and DP LIBS) has been investigated for multi-elemental analysis of the elements manganese, zinc, arsenic and lead in landfill leachates. Instrumental parameters such as detection delay and interpulse delay times were investigated in order to find the optimal operating values for multi-elemental analysis. The following emission lines were used: Mn II: 257.61; 259.37 and 260.56 nm; Zn II: 206.20 nm and Zn I: 213.85 nm; As I: 228.81; 234.98 nm and Pb I: 405.78 nm. All elements showed a strong enhancement factor (2.5) of DP LIBS signal intensities compared to SP LIBS. Analyses were performed using a background correction and the sum of the areas below each element emission lines. The limits of detection (LODs) achieved by SP LIBS were: 21.3, 77.5, 89.3, 38.9 mgkg-1 and for DP LIBS: 7.1, 13.4, 11.9 and 7.3 mgkg-1 respectively for Mn, Zn, As and Pb. The LOD values achieved by DP LIBS were improved by factors of 3, 6, 7.5 and 5 times respectively for Mn, Zn, As and Pb, with respect to SP LIBS. The average quantification errors were 7.5, 19.6, 38.2 and 28% for SP LIBS and 9.2, 21.3, 12.9 and 14.4% for DP LIBS respectively for Mn, Zn, As and Pb. The LIBS approach was demonstrated to be suitable for quantitative analysis of toxic elements and sufficiently fast for real time continuous monitoring of landfill leachates.

The Amazonian biome has a fundamental role in the global climate change scenario and the understanding the physicochemical aspect in Amazonian soils is of great importance. The nine horizons constituting a typical Amazonian Spodosol profile were studied by different complementary techniques: X-ray powder diffraction (XRPD), high-resolution transmission electron microscopy (HR-TEM), selected area electron diffraction (SAED) and scanning electron microscopy-energy-dispersive X-ray spectrometry (SEM-EDX). The XRPD analysis revealed the presence of different minerals along the profile, i.e. quartz from 0 to 214 cm (horizons from A1 to Bhs) and kaolinite from 215 to 290 cm (horizons from Tr to K2). The HR-TEM images and SAED patterns revealed the presence of kaolinite in the horizon A1, which was not detected by XRPD. Application of the Rietveld refinement enabled the quantification of the minerals in each horizon. The SEM-EDX analyses allowed to identifying changes in the horizon surface morphology as a consequence of ongoing deformation. A significant decrease of particle sizes and a marked variations of their surface features with increasing depth were measured by SEM. In conclusion, the results of this work provide new insights into the relationship between chemical properties and mineral changes along the soil profile.

The correct recognition of sweet orange (Citrus sinensis L. Osbeck) variety accessions at the nursery stage of growth is a challenge for the productive sector as they do not show any difference in phenotype traits. Furthermore, there is no DNA marker able to distinguish orange accessions within a variety due to their narrow genetic trace. As different combinations of canopy and rootstock affect the uptake of elements from soil, each accession features a typical elemental concentration in the leaves. Thus, the main aim of this work was to analyze two sets of ten different accessions of very close genetic characters of three varieties of fresh citrus leaves at the nursery stage of growth by measuring the differences in elemental concentration by laser-induced breakdown spectroscopy (LIBS). The accessions were discriminated by both principal component analysis (PCA) and a classifier based on the combination of classification via regression (CVR) and partial least square regression (PLSR) models, which used the elemental concentrations measured by LIBS as input data. A correct classification of 95.1% and 80.96% was achieved, respectively, for set 1 and set 2. These results showed that LIBS is a valuable technique to discriminate among citrus accessions, which can be applied in the productive sector as an excellent cost-benefit tool in citrus breeding programs.

Limited sensitivities of some laser-induced breakdown spectroscopy (LIBS) instruments may impair some applications. Although this drawback can be minimized by instrumental improvements, the complexity of operations and cost increases. In this work the principle of conventional dry ashing for sample preparation was evaluated as a simple and low-cost alternative to improve the sensitivity of LIBS analysis. Botanical, agronomic and industrial samples were analyzed. Samples were dry heated and their LIBS emission signals were evaluated. The results suggest the dry heating caused structural changes in samples providing greater availability of the analyte, which resulted in the enhancement of the signals. As proof of concept, the strategy was applied for Sr determination in plant leaves. Two Sr emission lines, enhanced after sample dry ashing were used. The developed methods showed similar performance featuring a good linear range (10 to 70 mu g g(-1)) with coefficient of correlations higher than 0.99. Additionally, the accurate determination of Sr in apple and peach leaves standard materials was achieved.

Stony monuments must continuously be safeguarded from damage caused over time, in particular from the detrimental effects of weathering. One of the new environmentally-friendly (nano) materials for stone reinforcement, particularly suitable for marble and calcareous (limestone, sandstone) artifacts, is Ca10(PO4)6(OH)2 hydroxyapatite (HAp), which has a considerably lower dissolution rate and solubility compared to CaCO3 calcite (the building block of marble materials): thus, HAp has been proposed for the protection of calcareous monuments against acidic rain corrosion. Promising results have been obtained, but further optimization is necessary as the treated layer is often incomplete, cracked and/or porous. Several parameters need to be optimized, in this way a homogeneous layer can be obtained, and consequently the formation of metastable can be avoided, soluble phases instead of HAp. These include: the pH of the starting solution; the effect of organic and inorganic additions in particular, that of ethanol, which is known to adsorb calcite, thus possibly favoring the growth of the HAp layer. The formation of HAp nanoparticles and their application on stony substrates has been investigated by means of a multi-methodological approach based on scanning electron microscopy, x-ray diffraction, small- and/or wide-angle x-ray scattering, Fourier-transform infrared spectroscopy, and finally, in situ measurements of laser-induced breakdown spectroscopy and acid attack preliminary tests on stony substrates.

Stony monuments must continuously be safeguarded from damage caused over time, in particular from the detrimental effects of weathering. One of the new environmentally-friendly (nano) materials for stone reinforcement, particularly suitable for marble and calcareous (limestone, sandstone) artifacts, is Ca10(PO4)6(OH)2 hydroxyapatite (HAp), which has a considerably lower dissolution rate and solubility compared to CaCO3 calcite (the building block of marble materials): thus, HAp has been proposed for the protection of calcareous monuments against acidic rain corrosion. Promising results have been obtained, but further optimization is necessary as the treated layer is often incomplete, cracked and/or porous. Several parameters need to be optimized, in this way a homogeneous layer can be obtained, and consequently the formation of metastable can be avoided, soluble phases instead of HAp. These include: the pH of the starting solution; the effect of organic and inorganic additions in particular, that of ethanol, which is known to adsorb calcite, thus possibly favoring the growth of the HAp layer. The formation of HAp nanoparticles and their application on stony substrates has been investigated by means of a multi-methodological approach based on scanning electron microscopy, x-ray diffraction, small- and/or wide-angle x-ray scattering, Fourier-transform infrared spectroscopy, and finally, in situ measurements of laser-induced breakdown spectroscopy and acid attack preliminary tests on stony substrates.

One of the main objectives in the steel production process is to obtain a blast furnace pig iron of good quality and at the lowest possible cost. In general, the quality of pig iron is evaluated on the basis of its chemical composition determined by X-ray fluorescence laboratory equipment. In the present study, the performance of a handheld (h) laser-induced breakdown spectroscopy (LIBS) instrument in the identification and the quantification of the relevant elements C, Mn, P, Si, and Ti in forty-six blast furnace pig iron samples was tested successfully. The application of two different models, i.e., univariate and multivariate partial least square (PLS) calibration and validation, to the whole LIBS data set showed that the latter approach was much more efficient than the former one in quantifying all elements considered, especially Si and Ti.

Laser-induced breakdown spectroscopy (LIBS) for atomic multi-elementary analyses, and Fourier transform infrared spectroscopy (FTIR) for molecular identification, are often suggested as the most versatile spectroscopic techniques. The present work aimed to evaluate the performance of both techniques, LIBS and FTIR, combined with principal component analysis (PCA) and machine learning (ML) algorithms in the detection of the composition analysis and differentiation of four different types of rice, white, brown, black, and red. The two techniques were primarily used to obtain the elemental and molecular qualitative characterization of rice samples. Then, LIBS and FTIR data sets were subjected to PCA and supervised ML analysis to investigate which main chemical features were responsible for nutritional differences for the white (milled) and colored rice samples. In particular, PCA data analysis suggested that protein, fatty acids, and magnesium were the highest contributors to the sample's differentiation. The ML analysis based on this information yielded a 100% level of accuracy, sensitivity, and specificity on sample classification. In conclusion, LIBS and FTIR coupled with multivariate analysis were confirmed as promising tools alternative to traditional analytical techniques for composition analysis and differentiation when subtle chemical variations were observed. (C) 2020 Optical Society of America

Fiber optics reflectance spectroscopy (FORS) and visible and near-infrared (VNIR) hyperspectral imaging (HSI) were applied to assess and control the laser cleaning process of a deeply darkened limestone surface collected from the historic entrance gate of Castello Svevo, Bari, Italy. Both techniques enabled us to verify the different degree of removal of a thick deposit of black crust from the surface of the walls. Results obtained were in good agreement with those of previous studies of the elemental composition achieved by application of laser-induced breakdown spectroscopy (LIBS). Coupling FORS and VNIR-HSI provided important information on the optimal conditions to evaluate the conservation status and determine the more appropriate level of cleaning restoration, thus avoiding over- and/or under-cleaning. maging spectroscopy was used to obtain maps of areas featuring the same or different spectral characteristics, so to achieve a sufficient removal of unwanted layers, without modifying the surface underneath, and to increase the efficiency of traditional cleaning techniques. The performance of the combined non-invasive approach used in this work shows promise for further applications to other types of rocks and highlights the potential for in situ assessment of the laser cleaning process based on reflectance spectroscopy.

The on-site detection of Si in pig iron is a crucial issue for the assessment of the quality of steel in its industrial production process. Laser Induced Breakdown Spectroscopy (LIBS) has the potentiality for such an application. In this work, it is proposed a LIBS methodology for the measurement of Si content, which is robust with respect to variable measurement conditions in an industrial environment, and capable of measuring readily Si percentages as low as 0.1%. The technique is based on a delayed detection that cleans the Si LIBS signal from overlapping Fe II lines, and on the proper choice of a reference Fe I emission feature that keeps track of the changing experimental conditions.

The tests commonly used to determine seed vigor are often laborious and time-consuming; thus, rapid methods are highly required for identifying high-vigor seeds among different batches. In this paper, we describe a novel approach able to distinguishing among batches of soybean seeds of different physiological quality based on their nutrient content measured by laser-induced breakdown spectroscopy (LIBS) assisted by multivariate analysis and machine learning algorithms. These include principal component analysis (PCA), support vector machine learning (SVM), linear and quadratic discriminant analyses (LDA and QDA), and nearest neighbor methods (KNN). A total of 92 measurements, 46 collected from batches marketed as low-vigor seeds and 46 as high-vigor seeds, were analyzed. The SVM method performed the best in discriminating among the batches. In particular, the quadratic SVM function could classify correctly 100% of the high-vigor samples and 97.8% of the low-vigor samples, whereas the cubic function yielded the opposite result; i.e., 97.8% of the high-vigor samples and 100% of the low-vigor samples were classified correctly. The best LIBS spectral region for the analysis was in the range of 350-450 nm, with calcium being the main distinguishing element. Thus, the LIBS technique combined with machine learning classification methods showed a promising potential for classifying soybean seed batches according to their physiological quality.

The associations between organic and mineral matter in the horizons of an Amazonian humiluvic Spodosol profile were studied by investigating the composition of the constituent organic compounds, the surface wettability and the relationships among the chemical, structural, and microstructural properties using Fourier Transform Infrared (FTIR) spectroscopy and contact angle (CA) analysis. With increasing the profile depth, the C[sbnd]H FTIR absorption decreased accompanied by a relative increase in C[dbnd]O FTIR absorption. A number of significant correlations were found between the experimental variables measured. In particular, the positive correlation between soil organic carbon (SOC) (1.43 to 31.13 g kg) and intensity of aromatic structural C[dbnd]C peak at 1620 cm downward the soil profile suggested the existence of higher amounts of more stable organic compounds with depth. The negative correlation between the intensity of aliphatic structures peaks from 3000 to 2800 cm and the clay minerals content indicated an increasing soil wettability with depth. The relative affinity of organic matter to mineral surfaces changed as a function of the mineral type distribution along the soil profile. As well, the chemical composition of organic matter and the type of phase fractions influenced whole soil wettability based on the SOC/clay relation to CA.