Laser induced breakdown spectroscopy; Rice husk; Coarse rice; Cr;X-RAY-FLUORESCENCE; SPECTROMETRY; CU

To validate the feasibility of laser induced breakdown spectroscopy (LIBS) in detecting Cr in rice of polluted areas of Poyang Lake in Jiangxi province, rice husk samples, coarse rice samples and polished rice samples in the area were selected randomly as targets. In this work, these samples were tested with LIBS and the content of Cr was acquired by flame atomic absorption (AAS) in fresh samples. LIBS spectra showed that Cr I 425. 43 nm, Cr I 427. 48 nm, Cr I 428. 97 nm and abundant mineral elements such as Fe and Si were detected clearly, but they were undetectable directly in coarse rice and polished rice. The results of AAS shows that Cr in rice husk is more than the corresponding coarse rice and the Cr in polished rice does not exceed the limited content of 1 mg . kg(-1) according to qualified national standards GB 2762-2012. The ratio between rice husk and coarse rice is about 78. 95, it displayed the distribution is clear. This shows that compared with coarse rice, the concentration enrichment ratio of Cr in rice husk is higher than the coarse rice. The results demonstrate that it is feasible to detect Cr in rice husk and coarse rice. Therefore, it is helpful to predict the distribution of heavy metals in agricultural products by means of green method without pollution.

laser-induced breakdown spectroscopy; phosphate rocks; organomineral fertilizers; principal components analysis; partial least squares regression;ELEMENTAL ANALYSIS; PLANT MATERIALS; SOIL; CHEMOMETRICS

A number of phosphate rocks and organomineral P fertilizers was analyzed comparatively by laser-induced breakdown spectroscopy (LIBS) in both single- and double-pulse modes associated with two chemometric methods, i.e., principal components analysis (PCA) and partial least squares regression (PLSR). PCA was demonstrated to be a valuable method for the identification of spectral differences between similar samples with only minor compositional differences. The raw and normalized LIBS spectra were able to provide effective identification and discrimination at a 95% confidence level and in good agreement with the reference concentrations. Results obtained confirm the promising potential of LIBS for the rapid classification of P fertilizers in situ.

LIBS; Cigarette brands; Elemental composition; Plasma parameters; LA-TOF-mass spectrometry;TOBACCO; CRYSTAL; SAMPLES; PLASMA

We present qualitative and quantitative analysis of the trace elements present in different brands of tobacco available in Pakistan using laser inducedbreakdown spectroscopy (LIBS) and Laser ablation Time of Flight Mass Spectrometer (LA-TOFMS). The compositional analysis using the calibration free LIBS technique is based on the observed emission spectra of the laser produced plasma plume whereas the elemental composition analysis using IA-TOFMS is based on the mass spectra of the ions produced by laser ablation. The optical emission spectra of these samples contain spectral lines of calcium, magnesium, sodium, potassium, silicon, strontium, barium, lithium and aluminum with varying intensities. The corresponding mass spectra of the elements were detected in LA-TOF-MS with their composition concentration. The analysis of different brands of cigarettes demonstrates that LIBS coupled with a LA-TOF-MS is a powerful technique for the elemental analysis of the trace elements in any solid sample. (C) 2017 Elsevier B.V. All rights reserved.

Laser-induced breakdown spectroscopy (LIBS); Tobacco leaves; Plasma; Limit of detection (LOD);

The rapid detection and real-time monitoring of plant elements is very important in the field of agriculture. A method using Laser Induced BreakdownSpectroscopy (LIBS) for the determination of the spectroscopy characteristics of Cu in tobacco was evaluated. To perform the calibration curve, several tobacco samples containing Cu arranged from 8. 59 to 156. 35 mu g . g(-1) were prepared. The amount of Cu prepared in laboratory was measured using atomic absorption spectroscopy. Experiments indicated that the characteristic spectrum of Cu at the wavelength of 324. 75 nm was quite clear, and easy to obtain. From the characteristic spectra obtained from Cu-contained samples, the temperature and density of the plasma induced by laser were calculated to be 39 458. 94 K and 0. 74X 10(16), respectively. The fitting curve between the intensity of the spectral lines and the sample concentrations was established with the correlation coefficient (r square) of 0. 98, the mean relative standard deviation (RSD) of 2. 59%, the limit of detection (LOD) of 7. 72 mu g . g(-1) and the spectral signal-noise ratio of 7. 86. The method was successfully applied to predict the Cu amounts in tobacco samples, which has a potential to be used in cigarette production lines and tobacco breeding.

INDUCED BREAKDOWN SPECTROSCOPY; OPTICAL-EMISSION-SPECTROMETRY; TRACE-ELEMENTS; MICRONUTRIENTS; MEMBRANE; CADMIUM; WATER

A novel calibration method was developed for the determination of macronutrients in suspension fertilizer samples by laser-induced breakdown spectroscopy(LIBS). The fertilizer samples were mixed with 10% m/v polyvinyl alcohol (PVA) and dried for approximately 2 h at 50 degrees C, resulting in a solid polymer film with the immobilized liquid sample. This study describes the use of LIBS and 12 normalization strategies to determine Cu, K, Mg, Mn and Zn as well as As, B, Ca, Cd, Cr, Fe, Na, P and Pb in suspension fertilizers by inductively coupled plasma optical emission spectrometry (ICP OES) and inductively coupled plasma mass spectrometry (ICP-MS) analyses. LIBS equipment parameters were chosen following optimization with a Doehlert design. The results clearly demonstrate a good agreement between the LIBS predicted concentrations and the reference concentrations determined by ICP OES after microwave-assisted acid digestion (AOAC 2006.03 Official Method). Correlations of R-2 = 0.9958, 0.9489, 0.9992, 0.9968 and 0.9809 for Cu, K, Mn, Mg and Zn, respectively, were obtained. Significant levels of potentially toxic elements such as 10 mg L-1 As, 4.0 mg L-1 Cd, 8.0 mg L-1 Cr and 20 mg L-1 Pb were detected after ICP-MS analysis. The results with low standard errors of prediction for LIBS (from 0.02 to 0.06%) indicate that this proposed suspension sample preparation procedure exhibits significant potential for the development and implementation of methods for determining essential nutrients in suspension fertilizers and other samples for which mineralization is difficult.

laser-induced breakdown spectroscopy; soil; magnesium; nonlinear multivariate calibration;RARE-EARTH-ELEMENTS; SAMPLES; LIBS; QUANTIFICATION; DIAGNOSIS; METALS

Laser-induced breakdown spectroscopy (LIBS) coupled with the nonlinear multivariate regression method was applied to analyze magnesium (Mg) contents in soil. The plasma was generated using a 100 mJ Nd:YAG pulsed laser, and the spectra were acquired using a multi-channel spectrometer integrated with a CCD detector. The line at 383.8 nm was selected as the analysis line for Mg. The calibration model between the intensity of characteristic line and the concentration of Mg was constructed. The traditional calibration curve showed that the concentration of Mg was not only related to the line intensity of itself, but also to other elements in soil. The intensity of characteristic lines for Mg (Mg I 383.8 nm), manganese (Mn) (Mn I 403.1 nm), and iron (Fe) (Fe I 407.2 nm) were used as input data for nonlinear multivariate calculation. According to the results of nonlinear regression, the ternary nonlinear regression was the most appropriate of the studied models. A good agreement was observed between the actual concentration provided by inductively coupled plasma mass spectrometry (ICP-MS) and the predicted value obtained using the nonlinear multivariate regression model. The correlation coefficient between predicted concentration and the measured value was 0.987, while the root mean square error of calibration (RMSEC) and root mean square error of prediction (RMSEP) were reduced to 0.017% and 0.014%, respectively. The ratio of the standard deviation of the validation to the RMSEP increased to 8.79, and the relative error was below 1.21% for nine validation samples. This indicated that the multivariate model can obtain better predicted accuracy than the calibration curve. These results also suggest that the LIBS technique is a powerful tool for analyzing the micro-nutrient elements in soil by selecting calibration and validation samples with similar matrix composition.

Laser-induced breakdown spectroscopy; Soil; Calibration curve; Chemometrics analysis;LIBS; CALIBRATION

Abundance or deficiency of soil elements is an expression of soil fertility. Rapid detection of elements in soil is a key point of front information acquirement tools in precision agriculture, and it also provides a theoretical basis for pollution prevention of soil heavy metal and sustainable development of agriculture. This research focused on using laser-induced breakdown spectroscopy LIBS) technique combined with calibration curve and chemometrics method to conduct the simultaneous quantitative analysis of multi-elements (Al, Fe, Mg, Ca, Na and K) in soil. First of all, five certified reference materials (CRM) of soil numbered GBW07446, GBW07447, GBW07454, GBW07455, GBW07456 were ablated by a laboratorial LIBS setup in air. 50 LIBS spectra of each type of soil were averaged to reduce the error in experiment process. By integrating the acquired LIBS emission spectra and atomic spectra database from national institute of standards and technology (NIST), analytical spectral lines and corresponding spectral regions were identified. Then, calibration curves of the intensity of a peak and integrated intensity of a peak or several peaks (peak area) coupling with the element content s were fitted. The results indicated that the linear relation from the calibration curves fitted by peak areas and element contents were superior to the calibration curves fitted using intensity of a peak and element contents (except the Fe). Meanwhile, partial least-squares regression (PLSR) was employed to build the quantitative model by using the selected spectral regions and corresponding element contents, which offered a promising result with relatively high RP and showed more advantages than the calibration curve method. The approach revealed that LIES technology combined with chemometrics methods displayed a bight prospect in the field of spectrochemical analysis. The achievements of the research not only provide a guide for detecting soil nutrient spatial distribution and precision fertilization technique, but also lay a theoretical foundation for developing the portable LIBS detector used in the field.

Coffee global quality; BGS; Classes discrimination; NIRS; LIBS;NEAR-INFRARED SPECTROSCOPY; MARKER COMPOUNDS; CUP QUALITY; BEANS; DEFECTS

Coffee is an important commodity and a very popular beverage around the world. Its economic value as well as beverage quality are strongly dependent of the quality of beans. The presence of defective beans in coffee blends has caused a negative impact on the beverage Global Quality (GQ) assessed by cupping tests. The main defective beans observed in the productive chain has been those Blacks, Greens and Sours (BGS). Chemical composition of BGS has a damaging impact on beverage GQ That is why analytical tools are needed for monitoring and controlling the GQ in coffee agro-industry. Near Infrared Spectroscopy (NIRS) has been successfully applied for assessment of coffee quality. Another potential technique for direct, clean and fast measurement of coffee GQ is Laser Induced Breakdown Spectroscopy (LIBS). Elements and diatomic molecules commonly present in organic compounds (structure) can be assessed by using LIBS. In this article is reported an evaluation of LIBS for the main interferents of GQ (BGS defects). Results confirm the great potential of LIBS for discriminating good beans from those with BGS defects by using emission lines of C, CN, C-2 and N. Most importantly, some emission lines presented strong linear correlation (r > 0.9) with NIRS absorption bands assigned to proteins, lipids, sugar and carboxylic adds, suggesting LIBS potential to estimate these compounds in unroasted and ground coffee samples. (C) 2017 Elsevier B.V. All rights reserved.

Wines; LIBS; Classification; Principal component analysis; Random forest; Matrix effect;LIQUID-LIQUID MICROEXTRACTION; ICP-MS; GEOGRAPHICAL ORIGIN; PROTECTED DESIGNATION; MULTIELEMENT ANALYSIS; SINGLE-PULSE; IDENTIFICATION; SAMPLES; LIBS; METALS

Laser-induced breakdown spectroscopy (LIBS) has been applied to classify French wines according to their production regions. The use of the surface-assisted (or surface-enhanced) sample preparation method enabled a sub-ppm limit of detection (LOD), which led to the detection and identification of at least 22 metal and nonmetal elements in a typical wine sample including majors, minors and traces. An ensemble of 29 bottles of French wines, either red or white wines, from five production regions, Alsace, Bourgogne, Beaujolais, Bordeaux and Languedoc, was analyzed together with a wine from California, considered as an outlier. A non-supervised classification model based on principal component analysis (PCA) was first developed for the classification. The results showed a limited separation power of the model, which however allowed, in a step by step approach, to understand the physical reasons behind each step of sample separation and especially to observe the influence of the matrix effect in the sample classification. A supervised classification model was then developed based on random forest (RF), which is in addition a nonlinear algorithm. The obtained classification results were satisfactory with, when the parameters of the model were optimized, a classification accuracy of 100% for the tested samples. We especially discuss in the paper, the effect of spectrum normalization with an internal reference, the choice of input variables for the classification models and the optimization of parameters for the developed classification models. (C) 2017 Elsevier B.V. All rights reserved.

IWDTF; LIBS; Animal manure composts; Cu; Zn;HEAVY-METAL CONTENTS; MULTIELEMENT ANALYSIS; ACCURACY IMPROVEMENT; MINERAL FERTILIZERS; LIVESTOCK FEEDS; TRACE-ELEMENTS; SPECTROMETRY; LIBS; CONTAMINANTS; TRANSFORM

Spectral denoising offers a basis for effective and accurate quantitative modeling of laser-induced breakdown spectroscopy (LIBS). To provide a solution for the defects of the traditional hard threshold function (HTF) and the soft threshold function (STF) for wavelet denoising methods, an improved wavelet dual threshold function (IWDTF) has been developed. Simulation analyses proved that the IWDTF could provide abetter denoising performance than the traditional functions. The IWDTF was applied to LIBS denoising and quantitative modeling of the Cu and Zn contents in representative Chinese aerobic composting samples. The results showed that the best spectral denoising effects for the Cu and Zn models were achieved when the adjustment parameters k(0), a, and theta were 0.9, 0.7 x lambda(1), and 0.1 x pi, and 0.2, 0.2 x lambda(1), and 0.1 x pi, respectively, and corresponding models' performances for Cu and Zn were both greatly improved, yielding R-p(2) of 0.9807 and 0.9177, RMSEP of 67.49 mg/kg and 84.92 mg/kg, and RPD of 3.12 and 3.07, respectively. (C) 2017 Published by Elsevier B.V.

Biochar-based fertilizers; Calcium; Libs; Internal standardization;SPECTROMETRY; SOILS; COAL

Biochar has gained agricultural importance as a soil amendment because of its important agricultural properties such as water retention, plant nutrient supplier, promoter of microorganism growth, sequestration action of atmospheric CO2, etc. Further, it is a low cost material being produced by recycling. Due to its active sites, biochar can adsorb nutrients so acting as a soil fertilizer. Thus the rapid assessment of nutrients in these materials is essential to ensure quality control for agricultural purposes. This work aimed to develop a simple analytical method based on Laser-Induced Breakdown Spectroscopy (LIBS) to determine Ca in biochar-based fertilizers. In particular, biochar samples enriched with Ca were prepared from peanut shells, residues of eucalyptus and banana fibers. The calibration standards were prepared by matrix matching using a biochar from eucalyptus residues. Different spectral preprocessing were evaluated to enhance the precision and accuracy of the method. However, the matrix effects demanded the use of internal standardization as the appropriate methodology to obtain the best accuracy. A linear correlation coefficient of 0.989 and a linear work range of 1.51-11.23% Ca were obtained using the proposed method, which yielded limits of detection and quantification of 0.45% e 1.51%, respectively. Calcium contents determined by LIBS in biochar-based fertilizers were in good agreement (paired t-test at 95% confidence level) with those determined by using High-Resolution Continuous Source Atomic Absorption Spectrometry (HR-CS FAAS) as the reference technique. Thus, the importance of internal standardization was demonstrated to be successful for the quantitative analysis of Ca in complex matrices like biochar-based fertilizers. (C) 2017 Elsevier B.V. All rights reserved.

INDUCED BREAKDOWN SPECTROSCOPY; YAG LASER; EMISSION SPECTROSCOPY; PLANT MATERIALS; HYDROGEN; DEUTERIUM; RESIDUES; ABLATION; NITROGEN

We report the experimental evidence of shock wave plasma generation by direct observation of the plasma propagation using 68 mJ 1064 nm Nd-doped yttrium aluminum garnet laser irradiation on a relatively soft organic sample in He ambient gas at 2 kPa. The density jump associated with the arrival of the plasma front at a certain position is detected by means of the highly sensitive interferometric technique, in conjunction with the observation of the first appearance of the plasma emission at the same position and time of the plasma front arrival. The result shows that the plasma front moves at the Sedov speed, which is typical of shock wave propagation, yielding an excellent emission spectrum for the harder sample. The shock front speed is further found to decrease in the case of a softer sample, resulting in lesser spectroscopic performance, as demonstrated by the emission spectra measured from mochi samples of different hardnesses. The result of this study is promising for paving the way to extending the laser-induced breakdown spectroscopy application to the much needed spectrochemical analysis of agricultural and food products. (c) 2017 Optical Society of America

Laser-induced breakdown spectroscopy (LIES); Soil; Heavy metal; Chemometrics methods; Quantitative analysis;NEURAL-NETWORK; LIBS

A large number of farm lands are contaminated by heavy metals in the process of industrialization and urbanization. Precise detection of heavy metals in soil offers valid reference for prevention and recovery of heavy metals in the field. In this research, Laser induced breakdown spectroscopy (LIBS) and chemometrics methods were employed to conduct quantitative analysis of heavy metals Pb and Cd in soil. Based on the pollution extent, soil samples with 15 concentration gradients of Pb and Cd were manually made up. Then, the LIBS emission lines of all soil samples were collected firstly. In order to eliminate errors and noise of spectral data, preprocessing methods called removal of abnormal data and normalization were used. Then, characteristic lines and spectral regions of Pb and Cd were determined based on our LIES spectra and Atomic Spectra Database (ASD) of National Institute of Standards and Technology (NIST). Quantity regression models based on multiple linear regression (MLR), partial least squares regression (PLSR), least squares support vector machine (LS-SVM) and back propagation-artificial neural network (BP-ANN) were set up and their results were compared. As a result, models based on non-linear methods (LS-SVM and BP-ANN) offered a promising results than the linear methods of MLR and PLSR. The probable reason was that non-linear methods had an advantage to deal with matrix effects of soil automatically. The results indicated that LIBS coupled with multiple chemometrics methods provided a brand-new analysis approach for heavy metals accurate detection in soil and it could be considered as an effective theoretical foundation of making protection and recovery decision for soil contaminated by heavy metals.

LIBS; Ash analysis; Wheat flour; PLS;LIBS

Ash content is an important quality control parameter in milling industry. Measurement of ash content is routinely performed using standard ash analysis method in which the sample is burned at 500-600 degrees C for 5-6 h. However, this method is not convenient for industrial applications, and thus, rapid and reliable methods are needed to be developed. The aim of this study was to develop a new method for ash analysis to be used in wheat milling fractions by using laser induced breakdown spectroscopy (LIBS). LIBS is an optic based multi-elemental, spectroscopic method which can analyze high number of samples in a considerably short time. In the study, wheat flour, whole wheat meal and semolina samples with different ash contents were analyzed using LIBS, and the spectra were evaluated with partial least squares (PLS) method. The results were correlated with the ones taken from standard ash analysis method. Calibration graph showed good linearity with the ash content between 0.48 and 2.44%, and 0.997 coefficient of determination (R-2). Limit of detection for ash analysis was calculated as 0.11%. The results indicated that LIBS is a promising and reliable method with high sensitivity for routine ash analysis in milling industry. (C) 2017 Elsevier Ltd. All rights reserved.

Laser-induced breakdown spectroscopy; LIBS; wines; matrix effect; trace elements;ATOMIC-ABSORPTION-SPECTROMETRY; X-RAY-FLUORESCENCE; LIQUID-LIQUID MICROEXTRACTION; QUANTITATIVE-DETERMINATION; SAMPLE INTRODUCTION; AQUEOUS-SOLUTIONS; TRACE-ELEMENTS; SINGLE-PULSE; ICP-OES; CLASSIFICATION

We developed a method for sensitive elemental analysis of wines using laser-induced breakdown spectroscopy (LIBS). In order to overcome the inefficiency of direct ablation of bulk wine (an organic liquid), a thin layer of wine residue was prepared on a metallic target according to an appropriated heating procedure applied to an amount of liquid wine dropped on the target surface. The obtained ensemble was thus ablated. Such a sample preparation procedure used a very small volume of 2mL of wine and took only 30min without reagent or solvent. The results show the detection of tens of metal and non-metal elements including majors (Na, Mg, K, Ca), minors, and traces (Li, B, Si, P, Ti, Mn, Fe, Cu, Zn, Rb, Sr, Ba, and Pb) in wines purchased from local supermarkets and from different production places in France. Commercially available wines were then spiked with certified standard solutions of Ti and Fe. Three series of laboratory reference samples were thus prepared using three different wines (a red wine and a white wine from a same production region and a red wine from another production region) with concentrations of Ti and Fe in the range of 1-40mg/L. Calibration graphs established with the spiked samples allowed extracting the figures-of-merit parameters of the method for wine analysis such as the coefficient of determination (R-2) and the limits of detection and quantification (LOD and LOQ). The calibration curves built with the three wines were then compared. We studied the residual matrix effect between these wines in the determination of the concentrations of Ti and Fe.

MATRIX CONVERSION; QUANTITATIVE-ANALYSIS; AQUEOUS-SOLUTIONS; METAL DETECTION; HEAVY-METALS; SPECTROMETRY; LIBS; MICROEXTRACTION; PLASMA; MEMBRANE

Laser-induced breakdown spectroscopy (LIBS) is a simple, fast, and direct technique for the elemental analysis of various samples. However, the practical application of this method in direct liquid analysis is limited due to its inherent disadvantages including surface ripples and extinction of emitted intensity. Applicable treatments of liquids always involve complicated procedures or additional instruments, which is disadvantageous to its analytical performance. In this study, we proposed a novel method for the LIBS analysis of liquid samples via a hydrogel-based solidification technique. In this new method, aqueous solution is directly poured into sodium polyacrylate resins. Owing to the high hydroscopicity of sodium polyacrylate resins, the resins quickly form a hydrogel and immediately solidify the liquid samples. After this, the LIBS analysis is directly performed. To estimate the analytical performance of this proposed method, calibration curves were established and limits of detection for Al, Cu, and Cr were obtained. The limits of detection (CODs) for the emission lines of Al(I) 308.21 nm, Cu(I) 324.75 nm, and Cr(I) 425.43 nm were 0.460 mu g mL(-1), 4.69 mu g mL(-1), and 4.44 mu g mL(-1), respectively. According to the obtained results, this proposed method demonstrates its better analytical performance in terms of CODs at the ppm level and requires shorter processing time as compared to other analytical methods based on the LIBS technique for liquid sample analysis. Especially, the short pretreatment of samples and simple auxiliary equipment make this hydrogel-based solidification method bring LIBS out of the laboratory for the direct analysis of environmental liquid samples. The feasibility and potential of this novel method have also been discussed for special analytical applications in slurry samples.

Nutritional evaluation; laser-induced breakdown spectroscopy; LIBS; Huanglongbing; HLB; phytosanitary control; diagnosis; data analysis; citrus diseases;GREENING DISEASE; FLUORESCENCE; LIBS; LEAVES; TOOLS

Huanglongbing (HLB) is the most recent and destructive bacterial disease of citrus and has no cure yet. A promising alternative to conventional methods is to use laser-induced breakdown spectroscopy (LIBS), a multi-elemental analytical technique, to identify the nutritional changes provoked by the disease to the citrus leaves and associate the mineral composition profile with its health status. The leaves were collected from adult citrus trees and identified by visual inspection as healthy, HLB-symptomatic, and HLB-asymptomatic. Laser-induced breakdown spectroscopy measurements were done in fresh leaves without sample preparation. Nutritional variations were evaluated using statistical tools, such as Student's t-test and analysis of variance applied to LIBS spectra, and the largest were found for Ca, Mg, and K. Considering the nutritional profile changes, a classifier induced by classification via regression combined with partial least squares regression was built resulting in an accuracy of 73% for distinguishing the three categories of leaves.

Soil; Plant; Fertilizer; DP LIBS analysis; Orthogonal geometry; Ablative energy;SIGNAL ENHANCEMENT; PLANT MATERIALS; PLASMA; LIBS; FERTILIZERS; ABLATION; SOILS; QUANTIFICATION; CONTAMINANTS; DEPENDENCE

A soil, a plant and a fertilizer sample were investigated by double-pulse (DP) laser-induced breakdown spectroscopy (LIBS) in orthogonal beam geometry using a reheating configuration. The DP-LIBS signal enhancement was evaluated with respect to the corresponding single-pulse (SP) LIBS as a function of the interpulse delay at various ablation energies. The maximum signal enhancement measured was 155-fold when low ablation energy (4 mJ) and an interpulse delay of 10 mu s were used. At high laser energies (>= 16 mJ) and interpulse delay of 0.6 mu s, the maximum signal enhancement was up to 3-fold. The effect of excitation energies and interpulse delays on emission line intensities was discussed in the various conditions used. The emission line enhancement measured for ionic lines was always higher than that of atomic lines. Plasma excitation temperature and electron density measured as a function of interpulse delays at various ablation energies were shown to be related to the emission line intensities. (C) 2017 Elsevier B.V. All rights reserved.

Mastitis; Bovine milk; LIBS; CN and C-2;BOVINE-MILK; DAIRY-COWS; SPECTROSCOPY; DIAGNOSIS

The present work focuses on the possibility of using the evolution of the spectral molecular bands of cyanide (CN) and carbon (C-2) in the laser-inducedbreakdown spectra of cow's milk for mastitis characterization. It has been found that the intensities of these molecular bands are directly proportional to the mastitis symptoms and consequently to the somatic cells count (SCC). The results obtained using laser-induced breakdown spectroscopy (LIBS) technique in the present measurements proved that it is a direct, straightforward, and easy method for discrimination between mastitis milk and normal milk. A linear relation between the CN and C-2 spectral line intensities and the corresponding average of the SCC has been obtained. Such linear relationship can be easily exploited in the identification and characterization of mastitic milk samples.

Laser-induced breakdown spectroscopy; Matcha; Green tea powder; Linear discriminant analysis (LDA);LIBS

The feasibility of using laser-induced breakdown spectroscopy (LIBS) combined with chemometrics methods for fast identification of matcha and green tea powder was investigated in this paper. The main differences between matcha and green tea powder are varieties of tea plants, cultivation management, growth time and processing technology. LIBS spectra between 230 to 880 nm of matcha produced by different manufacturers and green tea powder made with different fixation methods were selected and min-max normalization was the measure for preprocessing. Characteristic wavelengths were selected according to the X-variables loadings on the basis of principal component analysis (PCA), and then linear discriminant analysis (LDA) models were built based on characteristic wavelengths. The results showed that the LDA model based on characteristic wavelengths could identify matcha and green tea powder rapidly. Four characteristic wavelengths belong to C(I) 247. 94 nm, Mg(II) 279. 60 nm, Ca(II) 393. 45 nm and Fe(II) 766. 68 nm. The accuracy of the calibration and the prediction set all reached 100%. Laser-induced breakdown spectroscopy could accurately identify matcha produced by different manufacturers and green tea powder made with different fixation methods.

RISK-ASSESSMENT; PLANT MATERIALS; LIBS; PELLETS

In seeking a novel method with the ability of green analysis in monitoring toxic heavy metals residue in fresh leafy vegetables, laser-induced breakdownspectroscopy (LIBS) was applied to prove its capability in performing this work. The spectra of fresh vegetable samples polluted in the lab were collected by optimized LIBS experimental setup, and the reference concentrations of cadmium (Cd) from samples were obtained by conventional atomic absorption spectroscopy after wet digestion. The direct calibration employing intensity of single Cd line and Cd concentration exposed the weakness of this calibration method. Furthermore, the accuracy of linear calibration can be improved a little by triple Cd lines as characteristic variables, especially after the spectra were pretreated. However, it is not enough in predicting Cd in samples. Therefore, partial least-squares regression (PLSR) was utilized to enhance the robustness of quantitative analysis. The results of the PLSR model showed that the prediction accuracy of the Cd target can meet the requirement of determination in food safety. This investigation presented that LIBS is a promising and emerging method in analyzing toxic compositions in agricultural products, especially combined with suitable chemometrics. (C) 2017 Optical Society of America

laser-induced breakdown spectrometry; chlorine; plants; concrete;SPECTROSCOPY

We consider collinear and orthogonal beam-convergence configurations in double-pulse laser-induced breakdown spectrometry (LIBS, also known as laser-spark emission spectrometry) for chlorine determination in plants and concrete from the Cl I 837.59 nm line. We have observed that the signal-to-noise ratio is not much lower for the orthogonal configuration due to spatial instability in the second breakdown. At the same time, suppression of interfering molecular bands in this configuration lets us improve the sensitivity of LIBS for chlorine determination in plant material.

Manure; Calcuim; Laser-induced breakdown spectroscopy; Genetic algorithm;ELEMENTAL ANALYSIS; MEAT

In order to enhance the efficiency and safety of manure resource utilization, a rapid quantitative analysis of calcuim (Ca) content in manure is of great significance. In the presented study, the application of laser-induced breakdown spectroscopy (LIES) technique was used to quantitatively analyze Ca content in manure. Genetic algorithm (GA) was also applied to the LIBS to optimize the model. The dominant factors of LIES were set: 80 collection dots with 15% laser energy, 400 mu m spot size, delay time of 1. 0 mu s, and preforming pressure at 20 tons (T). The modeling results showed that the initial linear model constructed from the characteristic wavebands of Ca presented low precision and accuracy, partial least squares (PLS) models with wavebands at 190 similar to 950 nm exhibited the effects with coefficient of determination for the validation set (R-v(2)) and relative prediction deviation (RPD) of 0. 85 and 2. 13, respectively. The PLS model considered 12 variables, which were selected with GA in the waveband at 190 similar to 950 nm, and presented the R-v(2) and RPD of 0. 90 and 3. 04, respectively. They had presented relatively better results by avoiding complicated sample processing. It is pertinent to note that the efficiency of this method increased by a large margin when the variables were selected based on GA analysis. The results showed that LIES combined with GA can be used for quantitative analysis of Ca in manure.

medicinal herbs; essential and toxic metals; LIBS; ICP OES; chemometrics;INDUCED BREAKDOWN SPECTROSCOPY; PRINCIPAL COMPONENT ANALYSIS; TRACE-ELEMENTS; NEUTRON-ACTIVATION; INFUSIONS; INFORMATION; FINGERPRINT; CALCIUM; PLANTS; HONEY

Essential and toxic metals were determined in eighteen samples of medicinal herbs from Poland, Lithuania and Serbia by means of laser-induced breakdownspectroscopy (LIBS) and inductively coupled plasma optical emission spectrometry (ICP OES). Calcium, K and Mg concentrations were obtained in % (m/m) and other metals (Na, Co, Cu, Fe, Mn, Ni, Zn, Cd, Cr and Pb) in mg kg-1. The fact that the herb samples analyzed belonged to specific plant species and represented different morphological plant parts explained the characteristic distribution in two-dimensional scores plots obtained by principal component analysis (PCA). A strong correlation of LIBS results was achieved in comparison to those obtained by ICP OES for Ca, K and Mg. Differences in the types of infusions were observed, in that leaves are related to Zn and Ni concentrations, leaves and flowers to Co, Ca and Mn concentrations and flowers to K, Na, Mg and Fe content.

CHLOROPHYLL FLUORESCENCE; WATER-STRESS; SALINITY; ACCUMULATION; THERMOGRAPHY; TEMPERATURE; EFFICIENCY; PROTEIN; SAMPLES; SYSTEM

Drought stress disrupts the balance of macro- and micronutrients and affects the yield of agriculturally and economically significant plants. Rapid detection of stress-induced changes of relative content of elements such as sodium (Na), potassium (K), calcium (Ca) and iron (Fe) in the field may allow farmers and crop growers to counter the effects of plant stress and to increase their crop return. Unfortunately, the analytical methods currently available are time-consuming, expensive and involve elaborate sample preparation such as acid digestion which hinders routine daily monitoring of crop health on a field scale. We report application of an alternative method for rapid detection of drought stress in plants using femtosecond laser-induced breakdown spectroscopy (LIBS). We demonstrate daily monitoring of relative content of Na, K, Ca and Fe in decorative indoor (gardenia) and cultivated outdoor (wheat) plant species under various degrees of drought stress. The observed differences in spectral and temporal responses indicate different mechanisms of drought resistance. We identify spectroscopic markers of drought stress which allow for distinguishing mild environmental and severe drought stress in wheat and may be used for remote field-scale estimation of plant stress resistance and health. (C) 2017 Optical Society of America

MOISTURE-CONTENT; LIBS; CLASSIFICATION; CHEMOMETRICS; PLANTS

Tobacco mosaic virus (TMV) is one of the most devastating viruses to crops, which can cause severe production loss and affect the quality of products. In this study, we have proposed a novel approach to discriminate TMV-infected tobacco based on laser-induced breakdown spectroscopy (LIBS). Two different kinds of tobacco samples (fresh leaves and dried leaf pellets) were collected for spectral acquisition, and partial least squared discrimination analysis (PLS-DA) was used to establish classification models based on full spectrum and observed emission lines. The influences of moisture content on spectral profile, signal stability and plasma parameters (temperature and electron density) were also analysed. The results revealed that moisture content in fresh tobacco leaves would worsen the stability of analysis, and have a detrimental effect on the classification results. Good classification results were achieved based on the data from both full spectrum and observed emission lines of dried leaves, approaching 97.2% and 88.9% in the prediction set, respectively. In addition, support vector machine (SVM) could improve the classification results and eliminate influences of moisture content. The preliminary results indicate that LIBS coupled with chemometrics could provide a fast, efficient and low-cost approach for TMV-infected disease detection in tobacco leaves.

double pulse laser-induced breakdown spectroscopy; internal standard method; vegetable oil; chromium;LIBS

The safety quality of vegetable oil is very important for human life. The objective of this research is to determine the content of heavy metal chromium (Cr) in each of three kinds of vegetable oils (soybean oil, peanut oil, and corn oil) quantitatively by collinear double pulse laser-induced breakdown spectroscopy (DP-LIBS). In this study, a total of 24 vegetable oil samples are prepared, and each kind of vegetable oil has 8 samples. Fortune paulownia wood chips with a diameter of 20 mm and thickness of 3 mm are placed into the vegetable oil samples to collect the Cr element. After that, the 24 samples (fortune paulownia wood chips that have enriched Cr element) are dried in the oven, and the LIBS spectra of samples are acquired in a wavelength range of 206.28-481.77 nm by a dual-channel high-precision spectrometer. The spectral line of Cr (Cr I 425.39 nm) is chosen as the quantitative analysis spectral line, while CN (CN 421.39 nm) molecular spectral line, Ca (Ca I 422.64 nm) atomic spectral line and the sum of their spectral line intensities are selected as the internal standard lines. Then the calibration curves of Cr are obtained by the basic calibration method, single-line internal standard method (CN 421.39 nm or Ca I 422.64 nm as the internal standard line) and dual-line internal standard method (CN 421.39 nm and Ca I 422.64 nm as the internal standard lines). Finally, the validation samples are used to verify the performances of the calibration curves of Cr element. The results show that the values of fitting degree (R-2) of the basic calibration curves for three kinds of vegetable oils are all above 0.97, and the relative errors of validation samples with low concentration are bigger than those with high concentration. The values of (R 2) of calibration curves obtained by single-line internal standard method are above 0.98, and the relative errors of validation samples are lower than those obtained using basic calibration method. And the values of (R 2) of calibration curves for soybean oils, corn oils and peanut oils are 0.995, 0.992 and 0.996, respectively, with using dual-line internal standard method. The relative errors between the two validation samples are 12.8%, 1.73%, 9.19%, 6.05% and 6.23%, 6.69%, respectively. And the results obtained by the dual-line internal standard method are better than those obtained by the basic calibration method and single-line internal standard method. Thus it can be seen that the dual-line internal standard method can reduce the error of quantitative analysis effectively and improve the predicting ability of LIBS technique for Cr element detection in vegetable oil.

laser-induced breakdown spectroscopy; soil; manganese;QUANTITATIVE-ANALYSIS; LIBS; SAMPLES; ALLOY

Laser-induced breakdown spectroscopy (LIBS) has been applied to measure spectral characteristics and to perform quantitative analysis of the concentration of manganese in soil, an issue of great concern for precision agriculture. For the analysis, soil samples were compressed into pellets and a pulsed Nd:YAG laser was employed to produce the plasma in air at atmospheric pressure. Using this approach, we analyzed the time evolution of spectral characteristics and their dependence on the laser pulse energy. A calibration curve was constructed using reference sandy soil samples collected from a farm. An internal standard curve was used to improve the accuracy of the LIBS metrology for soil analyses. The results of this analysis demonstrated the usefulness of this method for analyzing the concentration of manganese in soil.

laser-induced breakdown spectroscopy; Pu'er tea leaves; quantitative measurement; external standard method; internal standard method; multiple linear regression method;WATER SOLUTION; LIBS; CALIBRATION; CHROMIUM; CR

Laser-induced breakdown spectroscopy (LIBS) is applied at natural atmosphere to compare the quantitative analysis performances of the toxic heavy metal element lead (Pb) in Pu'er tea leaves, determined by three calibration methods: the external standard method, the internal standard method, and the multiple linear regression method. The Pb I line at 405.78 nm is chosen as the analytical spectral line to perform the calibration. The linear correlation coefficients (R (2) ) of the predicted concentrations versus the standard reference concentrations determined by the three methods are 0.97916, 0.98462, and 0.99647, respectively. The multiple linear regression method gives the best performance with respect to average relative errors (ARE = 2.69%), maximum relative errors (MRE = 4.94%), average relative standard deviations (ARSD = 9.69%) and maximum relative standard deviations (MRSD = 24.44%) of the predicted concentrations of Pb in eight samples, compared to the other two methods. It is shown that the multiple linear regression method is more accurate and stable in predicting concentrations of Pb in Pu'er tea leaf samples.

ACCURACY IMPROVEMENT; WAVELET TRANSFORM; LIBS; SPECTROMETRY; PEAKS

The complex and serious spectral interference makes it difficult to detect trace elements in soil using laser induced breakdown spectroscopy (LIBS). To address it, LIBS-assisted by laser-induced fluorescence (LIES-LIP) was applied to selectively enhance the spectral intensities of the interfered lines. Utilizing this selective enhancement effect, all the interference lines could be eliminated. As an example, the Pb I 405.78 nm line was enhanced selectively. The results showed that the determination coefficient (R-2) of calibration curve (Pb concentration range = 14-94 ppm), the relative standard deviation (RSD) of spectral intensities, and the limit of detection (LOD) for Pb element were improved from 0.6235 to 0.9802, 10.18% to 4.77%, and 24 ppm to 0.6 ppm using LIBS-LIF, respectively. These demonstrate that LIBS-LIF can eliminate spectral interference effectively and improve the ability of LIBS to detect trace heavy metals in soil.

Laser induced breakdown spectroscopy; Chinese cabbage; Cadmiun; Variable screening;HEAVY-METALS; LIBS

Heavy metal residue in vegetables is a big concern in the whole world. The aim of this work is to explore the effect of multivariable selection on analyzing Cd in Chinese cabbage polluted in lab by collecting the spectra of laser induced breakdown spectroscopy (LIBS) from the samples. At the same time, the actual Cd content in samples was obtained by anodic stripping voltammetry (ASV). The LIBS spectral range in partial least square (PLS) model was screened by standard normal variable transformation (SNV), first derivative (FD), second derivative (SD) and center treatment (CT) for preprocessing spectra and the optimized method was used for the analysis of interval partial least square (iPLS) and synergy interval partial least square (SiPLS). The results indicated that the method of CT was the best as a comparison with PLS, iPLS and SiPLS. And the intervals of wavelength were 214.72-215.82 nm, 215.88-216.97 nm and 225.08 -226.35 nm by utilizing the optimized SiPLS. Here the root mean square error of cross validation (RMSECV) between real content and predicted ones was 1.487, the root mean squared error of prediction (RMSEP) was 1.094, the correlation coefficient (R) was 0.9942, and the average relative error (ARE) was 11.60%. The results displayed that LIBS could predict Cd in vegetables by multivariable selection of SiPLS and the accuracy could meet the requirement of rapid and green analysis of Cd in vegetables.

Laser-induced breakdown spectroscopy; Orthogonal dual-pulse; Spectral enhancement; Signal-to-background ratio; Plasma temperature; Electron density;OPTICAL-EMISSION; ENHANCEMENT

In order to improve the detection sensitivity and spectral characteristic of laser-induced breakdown spectroscopy (LIES), re-heating orthogonal dual-pulse configuration is adopted to analyze Fe, Pb, Ca and Mg contained in the sample and soil sample contained different concentrations of heavy mental Cr. Variation relationship between spectral intensity, signal-to-background(SBR) of four characteristic spectral lines Fe I : 404. 581 nm, Pb I : 405. 78 nm, Ca I 422. 67 rim and Mg I : 518. 361 nm and time interval of two laser pulses is discussed, the best time interval of two laser pulses is obtained 1. 0 s. In the condition of single pulse and dual-pulse, the enhancement factor of spectral intensity of four characteristic spectral lines Fe I : 404. 581 nm, Pb I : 405. 78 nm, Ca I : 422. 67 nm and Mg I : 518. 361 nm is respectively 2. 23, 2. 31, 2. 42 and 2. 10; The time evolution characteristic of spectral intensity of characteristic spectral lines Fe I : 404. 581 nm and Ca I : 422. 67 rim is considered, and also the variation relationship between spectral acquisition delay time and SBR of-four characteristic spectral lines, dual-pulse can prolong decay time of spectral intensity and improve the SBR of characteristic spectral lines; time evolution characteristic of plasma temperature and electron density is compared in the condition of single pulse and dual-pulse, maximum elevation of plasma temperature is found to be 730 K, and the maximum increase of electron density is 1. 8 X 10(16) cm(-3). The limits of detection of heavy mental Cr are obtained 38 and 20 mu g center dot g(-1) respectively in condition of single and double pulse, limit of detection of Cr is reduced approximately 2 times by the condition of re-heating orthogonal dual pulse. Results above indicate that reheating orthogonal dual-pulse can improve detection sensibility and spectral characteristic of LIBS technique, which provides an effective method for decreasing the limit of detection of elements.

Laser induced breakdown spectroscopy; Carrot; Elements; Curve fitting analysis; Plasma characterization;

The elemental composition of the carrot root was investigated by the laser induced breakdown spectroscopy by recording its emission spectrum. The recorded spectrum of carrot root pellet showed the presence of atomic lines of inorganic element as potassium (K), sodium (Na), iron (Fe), calcium (Ca), titanium (Ti), zinc (Zn), mercury (Hg), copper (Cu), magnesium (Mg), strontium (Sr), and cobalt (Co) while spectrum of fresh raw carrot depicted additional organic element as carbon (C), hydrogen (H), nitrogen (N) and oxygen (O). The produced plasma was characterized by characteristic parameters like plasma temperature, electron density, Lorentz fitting etc.

Stand-off LIBS; heavy metals; environmental samples;INDUCED BREAKDOWN SPECTROSCOPY

Interest in the use of laser-based sensors operating in stand-off mode is increasing due to the wide range of options offered in the evaluation of distant targets. In this work, a stand-off laser induced breakdown spectroscopy (ST-LIBS) system has been developed and demonstrated to determine the heavy elements in soil samples. Initially, different parameters of the device have been optimized in ambient atmosphere and tested for quantitative analysis of Nickel and Chromium at two different stand-off distances (1 m and 6 m). The prepared concentrations were in the range of 100 ppm to 600 ppm. The laser energy of 150 mJ was maintained through out the experiment and to obtain a real time situation the target was in static state.

Carbon dioxide laser; heavy metals; laser-induced breakdown spectroscopy; soil;METASTABLE HE ATOMS; SAMPLES; PLASMA; POLLUTION; INPUTS; GAS

A novel method of laser-induced plasma spectroscopy utilizing a pulsed transversely excited atmospheric CO2 laser has been developed for the high-sensitivity determination of heavy metals in soil. A coarse metal powder was used to trap the soil and to assist with plasma generation. When the CO2 laser(10.6 mu m, 1.5J, 200ns) was irradiated on the metal and soil powder, a high-temperature and long-lifetime luminous plasma was induced. Fine particles of soil were dissociated and were excited in the plasma region. The method was used for the rapid determination of Cr, Pb, and Hg in loam. The limits of detection for Cr, Pb, and Hg were approximately 0.8, 15, and 0.7mg/kg, respectively.

Cadmium and hexavalent chromium; laser-induced breakdown spectroscopy (LIBS); lead, quantitative analyses; plant materials;PLASMA-MASS-SPECTROMETRY; NEAR-INFRARED SPECTROSCOPY; ARTIFICIAL NEURAL-NETWORK; GANNAN NAVEL ORANGE; POWDER SAMPLES; DOUBLE-PULSE; IN-SITU; MULTIVARIATE-ANALYSIS; ELEMENTAL ANALYSIS; ATOMIC-ABSORPTION

Bearing the merits of rapid, minimally destructive, and simultaneous multi-element analyses, laser-induced breakdown spectroscopy (LIBS) shows its unique advantages in quantitative analyses of lead, cadmium, and hexavalent chromium in plant materials. However, the greatest challenge LIBS must confront is calibration. Various methods for calibration are proposed and put into effect; nevertheless, limits of detection acquired by LIBS are not acceptable when they are compared with the maximum residue limits drawn up by governments, and LIBS's performances in quantitative analyses are to be improved. This review summarizes recent studies of analyzing lead, cadmium, and hexavalent chromium in plant materials quantitatively by LIBS; weighs the strengths and weaknesses of their calibration methods; and recommends the combination of matrix-matched standards based on spiked sample materials and internal standard as well as chemometrics in complicated situations for calibration in LIBS. Selecting the emission line of the analyte, sample enrichment and signal enhancement are measures that this review puts forward to improve the performances of LIBS in calibration. These quantitative analyses of lead, cadmium, and hexavalent chromium in plant materials by LIBS provide an opportunity to be utilized in mapping distributions and remediation for soil and water, as well as supervision for agricultural products safety and pollution treatments.

LIBS; plasma; temperature; crops; weeds;INDUCED BREAKDOWN SPECTROSCOPY; TRITICUM-AESTIVUM L.; WINTER-WHEAT; SAMPLES; LIBS

The ability to distinguish between crops and weeds using sensors from a distance will greatly benefit the farming community through improved and efficient scouting for weeds, reduced herbicide input costs and improved profitability. In the present study, we examined the utility of femtosecond laser- inducedbreakdown spectroscopy (LIBS) for plant species differentiation. Greenhouse-grown plants of dallisgrass, wheat, soybean and bell pepper were evaluated using LIBS under an ambient environment. LIBS experiments were performed on the leaf samples of different plant species using a femtosecond laser system with an inexpensive lightweight detector. Temperatures of laser-induced plasma in plants depend on many parameters and were determined for each of the study species by the constituent elements interacting with femtosecond laser pulses. Using elemental calcium transitions in plant tissue samples to measure plasma temperatures, we report consistent differences among the four study species, with average values ranging from 5090 +/- 168 K (soybean) to 5647 +/- 223 K (dallisgrass).

INDUCED BREAKDOWN SPECTROSCOPY; CANEPHORA; ACID; TRIGONELLINE; VARIETIES; EMISSION; CAFFEINE; RATIOS

The elemental detection of green bean of arabica and robusta coffee from Gayo Highland, Aceh-Indonesia, has been identified by using fundamental Nd-YAG Laser at 10 Torr of surrounding air gas pressure for distinguishing the characteristics of both coffees. As the preliminary study, we have detected the elements of K 766.49 nm, Na 588.9 nm, Ca 393.3 nm, CN band at 388.3 nm, N 337.13 nm and C 247.8 nm of both coffees. It is noticed that the order of elements concentration from highest to lowest are Ca>K>CN>Na>N>C for arabica and K>Ca>CN >Na>C>N for robusta. The emission intensity of K 766.49 nm is almost same for both of coffee. However, the emission intensity of Na 588.9 nm is lower in Arabica coffee. To distinguish the Arabica coffee and Robusta Coffee, we take the ratio intensity of K/C, Na/C, CN/C, and Ca/C. It is found that the ratio intensities of CN/C and Ca/C in arabica bean are significantly different with robusta bean. That ratio intensities can be used as a marker to discriminate kind of coffee. We also noted that the arabica green bean is 1.3 harder than robusta green bean. These findings prove that the technique of laser-induced plasma spectroscopy can be used to make rapid identification of elements in coffee and can potentially be applied to measure the concentration of blended coffee for the purpose of authentication.

Chemometrics; Classification; Laser-induced breakdown spectroscopy; Variety; Walnut powder;JUGLANS-REGIA L.; SUPPORT VECTOR MACHINE; CLASSIFICATION; LIBS; CHEMOMETRICS; VARIABILITY; EMISSION; SAMPLE; OILS

Rapid classification of varieties of walnut powder is important to protect consumers against potential fraud because different varieties of walnut powder vary dramatically in quality, taste, and price. Laser-induced breakdown spectroscopy (LIBS) is a promising technology for on-line application that has the advantages of no or little sample preparation, fast response (usually seconds to minutes), and remote detection capability. In this research, LIBS and multi-variable analysis methods were applied to classify varieties of walnut powder for the first time. Before LIBS analysis, a fairly flat surface was provided to reduce fluctuation, and no other sample preparation was needed. After acquiring the LIBS spectra, principal component analysis (PCA) was used to make qualitative discrimination, and classification models were developed with partial least squares discrimination analysis (PLS-DA) and support vector machine (SVM). It was shown that three origins as well as different varieties from the same origin could be differentiated successfully by LIBS and chemometrics, while the discrimination of six different varieties with a single ""global"" model was not very successful. SVM could help to handle complex LIBS dataset, which improved the classified rate. The presented results provide the first proof-of-principle data for on-line application of the LIBS technique for classification of varieties of walnut powder.