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Investigation of minor elemental species within tablets using in situ depth profiling via laser-induced breakdown spectroscopy hyperspectral imaging
摘要： Laser-induced breakdown spectroscopy (LIBS) hyperspectral imaging allows for the determination of two-dimensional and three-dimensional spatial distributions of elemental species throughout complex samples. In this work, LIBS hyperspectral imaging was utilized to investigate minor elemental species within tablets. Representative LIBS spectra were initially collected on four complex, heterogeneous tablets, showing high concentrations of Ti in the tablet coating, with low and variable abundance of Na, Mg, and K. Principal component analysis revealed distinct resolution of the four tablets due to differences in Na, Mg, and K. Using two-dimensional LIBS hyperspectral imaging, spatial distributions of Na, Mg, and K within defined x and y regions of the tablet coating were generated. Subsequent three-dimensional LIBS hyperspectral imaging further elucidated the full x, y, and z spatial distributions of these minor elemental species within the tablet surface, tablet coating, and tablet core. As such, in situ depth profiling of the minor elemental species within each tablet was accomplished. Quantification of the homogeneity and uniformity of each tablet was determined. To our knowledge, this is the first report of multivariate analysis, LIBS, and LIBS hyperspectral imaging being utilized for the determination of both 2D and 3D spatial distributions of minor elemental species, along with quantification of tablet homogeneity, within tablets.
关键词： Chemical imaging,Laser-induced breakdown spectroscopy,Chemometrics,Pharmaceutical analysis,Atomic spectroscopy
更新于2025-09-23 15:19:57
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Optimization of measuring procedure of farmland soils using laser-induced breakdown spectroscopy
摘要： Laser-induced breakdown spectroscopy (LIBS) is an emerging multi-elemental analytical technique offering fast and simultaneous quantification of soil properties with minimal sample preparation and effective cost. Due to soil heterogeneity, spectral variation however limits the quantitative robustness. In this study, 348 soil samples were collected and prepared for acquisition of LIBS spectra. Influences of shot layer and number on LIBS quality were evaluated by spectral intensity and relative standard deviation (RSD). Effects of shot layer and number and five normalization procedures on LIBS ability to measure soil organic matter (SOM), total nitrogen (TN), and total soluble salt content (TSC), were evaluated using partial least squares regression (PLSR). Increasing shot number reduced LIBS spectral variance, thereby improving the quantitative accuracy of selected soil properties. Deep shot layers (4th or 5th shot layers) reduced the intensities of soil spectra and thereby decreased the quantitative accuracy for TSC. However, deep shot layers improved the SOM and TN prediction performances. Among the normalization approaches, the method based on the correction of Si line (DS) showed superior performance for improving quantitation of SOM and TN. The arithmetic average method (AA) was best for TSC prediction. Optimization of shot layer, number and normalization procedures of LIBS spectra resulted in fair prediction of SOM (residual prediction deviation of validation set, RPDV = 1.608), good prediction of TN (RPDV = 1.836), and very good quantitative analysis of TSC (RPDV = 2.456). Therefore, our findings illustrate very good potential for improving the quantitative accuracy of the LIBS soil spectra.
关键词： quantitative analysis,shot layer,soil properties,shot number,normalization methods,Laser-induced breakdown spectroscopy
更新于2025-09-23 15:19:57
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Quantitative in situ mapping of elements in deep-sea hydrothermal vents using laser-induced breakdown spectroscopy and multivariate analysis
摘要： This study describes a method to quantify the chemical composition of deep-sea hydrothermal deposits in situ using laser-induced breakdown spectroscopy (LIBS). Partial least squares (PLS) regression analysis is applied to spectra obtained using a long laser pulse with a duration of 150 ns. The number of measurements needed to address the spatial heterogeneity of samples is determined through high-resolution mapping of the elemental distribution in rock samples. PLS applied to laboratory measured seawater-submerged samples achieved an average relative error (RE) of 25% for Cu, Pb, and Zn compared to benchmark concentration values in cross-validation and validation studies, where both the benchmark concentration values and LIBS spectral data are made available with this publication. The PLS model was applied to LIBS signals obtained in situ from hydrothermal deposits at 1000 m depth in the ocean. The results show that target inhomogeneity limits the accuracy of the surface LIBS measurements compared to benchmark values from bulk analysis of samples. Making multiple measurements with small position offsets at each location improves the accuracy of estimates compared to an equivalent number of measurements at a single position. Maps of element distribution generated using quantified in situ data demonstrate how chemical survey outputs can be generated by combining LIBS with multivariate analysis. This enables real-time chemical feedback during deep-sea operations and chemical surveys in situations or with platforms where sample recovery is not possible.
关键词： Multivariate analysis,Laser-induced breakdown spectroscopy (LIBS),Deep-sea explorations,In situ chemical analysis,Seafloor mineral resources,Partial least squares regression analysis
更新于2025-09-23 15:19:57
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Geographical authenticity evaluation of Mentha haplocalyx by LIBS coupled with multivariate analyses
摘要： Mentha haplocalyx (mint) is a significant traditional Chinese medicine (TCM) listed in the Catalogue of “Medicinal and Food Homology”, therefore, its geographical origins (GOs) are critical to the medicinal and food value. Laser-induced breakdown spectroscopy (LIBS) is an advanced analytical technique for GOs certification, due to the fast multi-elemental analysis requiring minimal sample pretreatment. In this study, LIBS data of sampled mint from five GOs were investigated by LIBS coupled with multivariate statistical analyses. The spectral data was analyzed by two chemometric algorithms, i.e. principal component analysis (PCA) and least squares support vector machines (LS-SVM). Specifically, the performance of LS-SVM with linear kernel and radial basis function (RBF) kernel was explored in sensitivity and robustness tests. Both LS-SVM algorithms exhibited excellent performance of classification in sensitive test and good performance (a little inferior) in robustness test. Generally, LS-SVM with linear kernel equally outperformed LS-SVM based on RBF kernel. The result indicated the potential for future applications in herbs and food, especially for in situ GOs applications of TCM authenticity rapidly.
关键词： laser-induced breakdown spectroscopy (LIBS),geographical origin,herb authenticity,least squares support vector machines,Mentha haplocalyx
更新于2025-09-23 15:19:57
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Detail investigation of toxicity, bioaccumulation, and translocation of Cd-based quantum dots and Cd salt in white mustard
摘要： In this study, a model crop plant white mustard (Sinapis alba L.) was treated with an aqueous dispersion of silica-coated CdTe quantum dots (CdTe/SiO2 QDs) in a 72-hours short-term toxicity test. The toxicity was established via measurements of (i) the root length and (ii) the chlorophyll fluorescence. These results were compared to two other sources of cadmium, free Cd ions (CdCl2) and prime un-shell nanoparticles CdTe QDs. Tested compounds were applied in concentrations representing 20 and 200 μM Cd. The uptake and translocation of Cd were investigated using inductively coupled plasma optical emission spectrometry (ICP-OES) and the spatial Cd distribution was investigated in detail applying laser induced breakdown spectroscopy (LIBS). The LIBS maps with a lateral resolution of 100 μm were constructed for the whole plants, and maps with a lateral resolution of 25 μm (micro-LIBS arrangement) were used to analyse only the most interesting parts of plants with Cd presence (e.g. root tips or a part crossing the root into the above-ground part). Our results show that the bioaccumulation patterns and spatial distribution of Cd in CdTe/SiO2 QDs-treated plants differ from the plants of positive control and CdTe QDs. Fluorescence microscopy photographs revealed that CdTe/SiO2 became adsorbed onto the plant surface in comparison to CdTe QDs. Further, a physico-chemical characterization of QDs before and after the test exposure showed only minor changes in the nanoparticle diameters and no tendencies of QDs for agglomeration or aggregation during the exposure.
关键词： nanoparticles,cadmium,laser-induced breakdown spectroscopy,Sinapis alba L.,uptake,translocation
更新于2025-09-23 15:19:57
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Spatial confinement effect on CN emission from nanosecond laser-induced PMMA plasma in air
摘要： In this paper, a PMMA target was ablated to study spatial confinement effect on CN emission of laser-induced PMMA plasma in air. Four cylindrical cavities with same depth and different diameters (4, 6, 8, and 10 mm) were used to confine the nanosecond laser-ablated PMMA plasma plume. Laser pulse energies were 40, 50, and 60 mJ. The influence of cavity diameter on emission band and vibration temperature of CN molecule was demonstrated, the results showed an obvious increase in the emission and vibration temperature of CN molecule by using the cylindrical cavity. When the cavity diameter was smaller at a fixed laser energy, the emission enhancement of CN molecule appeared earlier, and the CN molecule had stronger emission and vibration temperature. For a fixed diameter cavity, when the laser energy was higher, the CN molecule presented stronger emission and higher vibration temperature, and the emission enhancement also appeared earlier. The enhanced effect on the spatial confinement mainly comes from shock wave produced by the laser-induced PMMA plasma. The spatial confinement cavity can reflect the shock wave, and the shock wave compresses the plasma plume, resulting in an improvement in the temperature and density of the plasma. Therefore, the optical emission of CN molecule increases as the shock wave interacts with the PMMA plasma.
关键词： CN,PMMA,laser-induced breakdown spectroscopy,spatial confinement
更新于2025-09-23 15:19:57
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Multivariate analysis and laser-induced breakdown spectroscopy (LIBS): a new approach for the spatially resolved classification of modern art materials
摘要： The ever-increasing speed of exchange of ideas, information, and culture allows contemporary art to be in constant growth, especially concerning the choice of artistic materials. Their characterization is not only crucial for the study of artistic techniques but also for research into the stability of the material and, consequently, the best preservation practices. For this aim, an analytical method should have the advantages of not requiring sample preparation, performing superficial micro-analysis, and obtaining detailed spectral information. For this study, laser-induced breakdown spectroscopy (LIBS) was employed. It was used for the identification of modern paints composed of inorganic pigments and organic binders, such as acrylics, alkyds, and styrene-acrylics. Principal component analysis (PCA) was used to classify the different pure materials, above all, the polymeric binders. To distinguish the paint mixtures, whose LIBS spectral results were more complex due to the pigment/binder interaction, a statistical method recently employed in the cultural heritage field was chosen, namely, random decision forest (RDF). This methodology allows a reduction of the variance of the data, testing of different training data sets by cross-validation, an increase of the predictive power. Furthermore, for the first time, the distribution of different inorganic pigments and organic binder materials in an unknown sample was mapped and correctly classified using the developed RDF. This study represents the first approach for the classification of modern and contemporary materials using LIBS combined with two different multivariate analyses. Subsequent optimization of measurement parameters and data processing will be considered in order to extend its employment to other artistic materials and conservation treatments.
关键词： Laser-induced breakdown spectroscopy,Inorganic pigments,Random decision forest,Organic binders,Principal component analysis
更新于2025-09-23 15:19:57
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Lens-to-sample distance effect on the quantitative analysis of steel by laser-induced breakdown spectroscopy
摘要： The focusing position of the laser affects the characteristics of the laser-induced plasma, which in turn influences the signal stability and the quantitative analysis of laser-induced breakdown spectroscopy. In this study, six standard alloy steels are used as the samples, and the trace elements including Si, Mn, Cr are quantitatively analyzed by internal standard method. The variations of line intensity, background noise intensity, signal-to-background ratio (SBR), detecting sensitivity and detection of limit (LOD) of the element with lens-to-sample distance (LTSD) were investigated. The results show that both the intensities of the analytical line and the background noise reached a maximum when the LTSD is 94 mm. While the corresponding SBR is relatively low. For quantitative analysis, it is observed that the change of the detection sensitivity with LTSD has the similar trend with that of SBR. That is, the detection sensitivity has a lower value when the LTSD is 94mm. However, when the LTSD changes from 93mm to 99mm, LODs of the three elements are maintained at a small value. The present results indicate that for quantitative analysis of LIBS, the intensities of the analytical line and the background noise should be comprehensively considered when optimizing the laser focusing position.
关键词： Laser-induced breakdown spectroscopy,Quantitative analysis,Line intensity,Lens-to-sample distance
更新于2025-09-23 15:19:57
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Determination of Lead and Chromium in Aloe Vera Pulp and Aloe Vera-Based Cosmetics by Laser-Induced Breakdown Spectroscopy (LIBS)
摘要： This study focuses on the application of laser-induced breakdown spectroscopy (LIBS) to determine lead and chromium in pristine aloe vera and aloe vera based beauty soaps using the second harmonic (532 nm) of a Q-switched Nd:YAG laser. The optimal experimental conditions were evaluated to improve the sensitivity of the detection system by a parametric dependence study. The atomic transition lines at 405.7 nm and 425.4 nm were used as the analytical lines to determine lead and chromium, respectively. The LIBS system was calibrated for these toxic elements and the samples under analysis included 8.00–15.00 ppm by mass of lead and 5.00–12.00 ppm by mass of chromium, which are far above the safe permissible levels of these elements (i.e., 0.50 ppm for Pb and 1.00 ppm for Cr). The quantitative results were checked before and after normalization with the background and better outcomes were obtained when the spectrum was normalized with the background. The LIBS results were compared to the outcomes of selected samples by a standard analytical method, inductively coupled plasma – optical emission spectroscopy (ICP-OES). Both outcomes were in outstanding conformity implying the reliability of the LIBS measurements. The current study is attractive for the general evaluation of human health and specifically for the analysis of aloe vera based cosmetics.
关键词： chromium,Laser-induced breakdown spectroscopy (LIBS),aloe vera,lead
更新于2025-09-23 15:19:57
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Comparative identification of citrus huanglongbing by analyzing leaves using laser-induced breakdown spectroscopy and near-infrared spectroscopy
摘要： In this work, laser-induced breakdown spectroscopy (LIBS), near-infrared spectroscopy (NIR), and LIBS joint NIR (LIBS–NIR) were investigated for the identification of citrus huanglongbing (HLB). The content of minerals like calcium (Ca), zinc (Zn), and potassium (K) was obtained by atomic absorption spectroscopy (AAS). The spectra of LIBS, NIR, and LIBS–NIR were operated by discriminating analysis (DA) and multi-layer perception (MLP). The results of AAS and Kolmogorov–Smirnov Test (K–S test) showed that the Ca and Zn decreased significantly in HLB infected leaves, but K is not significantly influence by HLB. The LIBS–NIR combining with MLP-PCA had highest diagnostic accuracy of 89.5% and 95.7% in training and test set, respectively. These results proved that joint spectrum of LIBS–NIR is a feasible method to identify citrus HLB.
关键词： laser-induced breakdown spectroscopy,minerals,identification,citrus huanglongbing,near-infrared spectroscopy
更新于2025-09-23 15:19:57