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A simple cost-effective laser-induced breakdown spectroscopy (LIBS) instrument was used for quantification of major elements in several nickel alloys and also sorting them. A compact low-power diode-pumped solid-state laser and a miniature low-resolution spectrometer were assembled for the LIBS instrument. Material properties of the nickel alloys depend mainly on the composition of the major elements, Ni, Cr, and Fe, ranging from a few to ∼60 wt%. The emission peaks at 547.7 nm, 520.4 nm, and 438.1 nm for Ni, Cr, and Fe, respectively, were chosen for this analysis. The analytical performance was found to be enough for the quantification of Ni, Cr, and Fe in the nickel alloys. Limits of detection and accuracy were estimated to be a few weight percent (wt%) and measurement precisions were less than 10% in terms of relative standard deviation. The calibration performance of this intensity-based method was compared with that of the “ratio method” which is used in conventional optical emission spectroscopy analyses. The comparison indicates that the intensity-based method is more appropriate with the low-performance LIBS instrument that detects emission peaks of only a few major elements. Also, multivariate modeling of the six different nickel alloy samples based on the emission peak intensities of Ni, Cr, and Fe was performed using k-nearest neighbors (KNN) and linear discriminant analysis (LDA). The KNN and ordinary LDA models showed 95.0% and 98.3% classification correctness for the separate test data set, respectively. To improve classification performance further, the two-step LDA model was trained. In this approach, the two closest sample classes responsible for the decrease in the classification correctness were separately modeled in the second step to exploit their difference effectively. The two-step LDA model showed 100% correctness in classifying the test objects. Our results indicate that such a low-performance LIBS instrument can be effectively utilized for quantitative analysis of the major elements in the nickel alloys and their rapid identification or sorting in combination with an appropriate multivariate modeling algorithm.

Laser-induced breakdown spectroscopy (LIBS) and near-infrared (NIR) spectroscopy, enabling the measurement of raw bile directly without sample pretreatment, were cooperatively combined to enhance the discrimination of gallbladder cancer (GBC) from other diseases of gallstone and gallbladder (GB) polyp. Since elemental contents and metabolite compositions of bile vary according to the pathological conditions of pancreaticobiliary patients, the use of complementary information could be synergetic to improve disease identification accuracy. The ratios of Mg and Na peak areas (

Ceria doped with low-valence lanthanide cations has been introduced for use as an electrolyte in solid oxide fuel cells (SOFCs). Improving the performance of SOFCs using doped ceria requires an increase in ion mobility across the solid electrolyte. Recently, ceria doped with multiple low-valence lanthanide ions has been found to show better ion mobility than that of the singly doped one. In this work, the feasibility of laser-induced breakdown spectroscopy (LIBS) for stoichiometric analysis of doubly doped ceria, Sm

Laser-induced breakdown spectroscopy (LIBS) was explored for the first time for discrimination of gallbladder (GB) polyp and GB cancer (GBC) by direct measurement of raw bile juice without pretreatment.

Graphitic carbon nitride (g-C3N4) is a promising two-dimensional semiconducting material that has shown potential for various applications in the field of photocatalysts due to its thermal stability and excellent electronic properties. However, pristine g-C3N4 has a wide optical band gap, which limits the active absorption of solar light in the spectral region below 420 nm. One way to improve the optical character is by doping with a sulfur heteroatom to make sulfur-doped g-C3N4 (S-g-C3N4), which has a smaller band gap relative to the pristine g-C3N4. Herein, we have developed a new type of S-g-C3N4 composite incorporating eosin-Y (EY–S-g-C3N4) by employing the co-polymerization approach between eosin-Y (EY) and S-g-C3N4. In this composite, eosin-Y moieties act as external photosensitizing groups. The optical characteristics of EY–S-g-C3N4 were investigated using density functional theory, various optical spectroscopies, and various imaging techniques. From those characterizations, it was found that the appearance of the charge-transfer state in the low band gap regime improved the light-harvesting ability relative to the g-C3N4 and S-g-C3N4. The use of the EY–S-g-C3N4 photocatalyst for the regeneration of NADH and NADPH showed quite excellent efficiencies of 64.38% and 81.14%, respectively. In addition, it showed the high conversion efficiency of sulfide to sulfoxide with an yield of 99.6%. This research highlights the potential application of the EY–S-g-C3N4 composite in the field of organic transformation based on photoinduced conversion.

Laser-induced breakdown spectroscopy (LIBS) and near-infrared (NIR) spectroscopy were combined to enhance discrimination of soybean paste samples according to geographical origin. Since element and organic component compositions of soybean pastes depend on soybean cultivation areas and fermentation conditions, utilization of two complementary spectroscopic signatures would be synergetic for the discrimination. When the areas of C (A

Feasibility of a simple laser-induced breakdown spectroscopy (LIBS) device has been investigated for the analysis of Mg and Ca in edible salts. The LIBS spectrometer was assembled with a compact low-power diode-pumped solid-state laser (DPSSL) and a non-gated low-resolution handheld spectrometer. A simple sampling process was employed for on-site application. A piece of filter paper was dipped in the aqueous solution of a sample salt and dried for analysis using LIBS. Maintaining the sample surface height at the optimum position was critical to generate plasmas persistently due to the low pulse energy of the DPSSL. The varying height of the filter paper surface was monitored and compensated, while the sample stage was translated to collect spectra from different positions. The variation of line intensities of Mg and Ca could be attributed to the inhomogeneous distribution of dry residues. To correct this, the peak that consists of the Na(I) and C(II) lines at 568 nm was employed as a reference signal for intensity normalization of the analyte Mg(II) and Ca(II) lines. For edible salt products, the normalized Mg(II) and Ca(II) line intensities could be well correlated with the concentrations of Mg and Ca determined using inductively coupled plasma optical emission spectroscopy. Our results indicate that a simple LIBS device in combination with the simple sampling method is promising as an on-site salt quality assessment methodology.

One of the unique laser-induced breakdown spectroscopy (LIBS) platforms, a compact device, has been considered for use in various applications because of portability and cost effectiveness. The performance of a simple LIBS device assembled with a compact, low-power, diode-pumped solid-state laser and a miniature, non-gated spectrometer was investigated for analysis of low-alloy steel samples. The low spectral resolution (∼0.9 nm) precluded observation of any single resolved analyte lines for Mn, Cr, Ni, and Ti. However, partial least squares-regression modeling extracted the unresolved spectral features correlated to the analyte concentrations successfully. For the highly congested wavelength regions selected for modeling Ni and Ti concentrations, finding reliable location of baseline to be subtracted was very difficult. This could be circumvented by using the first derivatives of LIBS spectra. Our results indicate that the first derivation of LIBS spectra can be used to further improve the analytical performance of a simple, low-resolution LIBS device. Additionally, this implies that appropriate data preprocessing can assist in downsizing a LIBS spectrometer, especially for the sample with matrix elements showing dense rich emission-line structure.

Analytical methods for the determination of inorganic arsenic species have attracted much attention due to the high toxicity of these compounds and related legislative regulations for food. A new m...

Gadolinium-doped ceria (GDC) is a functional ceramic material used for the electrolytes and electrodes in solid oxide fuel cells (SOFCs). As the more SOFCs are used in power generation, a demand on the practical and reliable analytical methodology for GDCs would increase further. In this work, we investigated feasibility of the laser-induced breakdown spectroscopy (LIBS) instrument assembled with a compact low-power diode-pumped solid-state laser and a hand-held low-resolution spectrometer for stoichiometric analysis of GDCs. LIBS uses laser ablation sampling that greatly simplifies the sample preparation process by removing acid digestion, high temperature treatment, and further dilution indispensable for conventional elemental analyses. In the observed wavelength region of 397 – 450 nm, Gd and Ce poured out rich emission lines and those were unable to be resolved by the low-resolution spectrometer. However, the characteristic spectral features of Gd and Ce were successfully extracted from the unresolved spectra and well correlated with the mole fractions of Gd in GDCs by means of partial least squares-regression (PLS-R). Our results indicate that the low-performance LIBS instrument and PLS-R calibration can be a cost-effective practical technique for stoichiometric analysis of GDCs.

We report laser-induced breakdown spectroscopy (LIBS) analysis of gadolinium (Gd) in gadolinium-doped ceria (GDC), the functional material used in solid oxide fuel cells (SOFCs). LIBS using laser ablation to atomize solid samples is competent in sampling the refractory ceria. Also, a few to 10 mol.% of Gd is doped in GDC to be used for SOFCs. Such a high concentration requires additional dilution after acid digestion of the sample for conventional analyses. LIBS with typical dynamic range from ppm to percent can analyze the high concentrations of Gd directly. GDCs with 1–10 mol.% of Gd were synthesized by glycine-nitrate process and the LIBS spectra were recorded. In spite of these advantages of LIBS, calibrating LIBS spectra to the concentrations of Gd is quite challenging due to rich emissions of Ce. Six prominent Gd I lines were selected for univariate calibrations and the whole spectra were used for multivariate partial least squares-regression (PLS-R) modeling. The PLS-R model considering emission intensities of both matrix and analyte elements outperformed the univariate calibrations. Our results suggest that LIBS in combination with multivariate analysis can be useful as an analysis method for the refractory lanthanide oxide materials.

We report soft independent modeling of class analogy (SIMCA) analysis of laser-induced plasma emission spectra of edible salts from 12 different geographical origins for their classification model. The spectra were recorded by using a simple laser-induced breakdown spectroscopy (LIBS) device. Each class was modeled by principal component analysis (PCA) of the LIBS spectra. For the classification of a separate test data set, the SIMCA model showed 97% accuracy in classification. An additional insight could be obtained by comparing the SIMCA classification result with that of partial least squares discriminant analysis (PLS-DA). Different from SIMCA, the PLS-DA classification accuracy seems to be sensitive to addition of new sample classes to the whole data set. This indicates that the individual modeling approach (SIMCA) can be an alternative to global modeling (PLS-DA), particularly for the classification problems with a relatively large number of sample classes.

Diffuse optical reflectance spectroscopy (DORS) and laser-induced breakdown spectroscopy (LIBS) were applied for classification of edible salts. DORS and LIBS spectra were recorded for 21 edible salts products. Principal component analysis was performed to reduce variables for each spectroscopic data. DORS and LIBS classification models using principal component scores of the calibration dataset were constructed. Each model was validated for external test dataset using the k-nearest neighbors algorithm. The LIBS model provided better classification accuracy than the DORS model. However, the DORS model showed higher accuracy for particular salt samples. This indicates that reflectance spectra possess independent chemical information from that provided by LIBS spectra. Complementary effects of DORS and LIBS on improving the classification accuracy were investigated for the classification problem composed of selected samples. DORS-LIBS fused models were constructed with different weighting factors for DORS variables. The optimum fused model showed higher classification accuracy than those of either DORS or LIBS models. Our results suggest that the two simple spectroscopic techniques can be combined for highly accurate classification of edible salt products.

An analytical method was developed for the extraction and determination of total arsenic and arsenic species in seafood by ion chromatography coupled with end-on-plasma atomic emission spectrometry. Sample preparation included a selective extraction method, and the optimization for separation and detection of arsenic species was performed by important instrumental and methodological parameters. The lack of loss or transformation of arsenic species in samples was also confirmed with the analytical method. Good recovery efficiency (98.2 ~ 99.1%) was obtained for the arsenic species with the selected extraction method. In this study, several kinds of seafood (snow crab, red snow crab, octopus, octopus minor, and squid) and seaweed (red laver, green laver, sea tangle, sea mustard, and hizikia) were investigated with the analytical method. All samples were first dried and ground to fine powder before use. The main arsenic species found in these seafoods was non-toxic arsenobetain (AsB). Its highest concentration was found in red snow crab samples (152 ± 4 mg/kg, dry weight). Other arsenic species (As3+, As5+, monomethylarsonic acid [MMA] and dimethylarsinic acid [DMA]) were not detected in these seafood samples. The major arsenic species found in hizikia samples was As5+. Its concentration was 34.0 ± 0.4 mg/kg (dry weight). Arsenic species (As3+, As5+, MMA, DMA, and AsB) were not found in green laver, sea tangle, red laver, or sea mustard samples.

A compact laser-induced breakdown spectroscopy (LIBS) instrument and a simple sample preparation method were developed for rapid on-site analysis of Mg, Ca, and K in edible sea salt products. The LIBS instrument was assembled using a small diode-pumped solid-state laser and a handheld spectrometer. Aqueous solutions of salts were prepared and sampled by using pieces of filter papers. The dried filter paper was attached on the flat surface of a silicon wafer and then analyzed by LIBS. Calibration curves were obtained using binary mixtures of ${\rm NaCl} {-} {{\rm MgSO}_4}$NaCl-MgSO4, ${\rm NaCl} {-} {{\rm CaCl}_2}$NaCl-CaCl2, and NaCl-KCl and used to estimate the concentrations of Mg, Ca, and K in 13 edible sea salt products. Matrix effects on the results from LIBS were identified in comparison with those from inductively coupled plasma optical emission spectroscopy. This indicates that the matrix of sea salt samples is significantly different from that of the binary mixture standards. The sea salts with known concentrations of Mg, Ca, and K were employed to match the matrices of samples and standards. This improved analysis accuracy remarkably. Furthermore, an alternative indirect method for estimating the concentration of K was suggested on the basis of the strong positive correlations observed between the concentrations of Mg and K in the sea salt samples.

Qualitative and quantitative determination of total arsenic content and arsenic species in rice is very important because rice is one of the main sources of human arsenic intake. However, extraction and determination of arsenic species in rice has been very difficult due to severe matrix interference. An alternative analytical method was developed in this study to determine arsenic species in rice by using ion chromatography coupled to inductively coupled plasma-mass spectrometry. Two internal standards were used. The first internal standard was injected before sample introduction to correct signal change with time. The second internal standard was spiked into the sample to reduce matrix interference. Using the developed method, recoveries of dimethylarsinic acid, monomethylarsonic acid, and inorganic arsenic compared to certified values (NIST SRM 1568b rice flour) were 116%, 107%, and 92%, respectively.

Solvent extraction and separation of Co (0.8 g/L), Ni (0.3 g/L), and Mg (0.5 g/L) with various cationic extractants (D2EHPA, PC88A, Cyanex 272, Versatic 10, and Cyanex 301) from chloride solutions are investigated. The effects of initial pH, extractant concentration, and saponification degree on the extraction and separation of metals are also studied. Co was preferentially extracted over Mg and Ni by saponified PC88A and Cyanex 272. On the other hand, Cyanex 301 and Versatic 10 exhibited selectivity on the extraction of both Co and Ni over Mg. HCl solution selectively stripped Co over Ni from the loaded Cyanex 301, which made it possible to separate the two metals during the stripping process.

【This study was conducted in an effort to identify the fluctuation of species according to space and time by collecting information on samples of Korean Sphingid moths housed in Korea. The number of Sphingidae moth species housed in Korea was found to be 53. As 48 species and 47 species were found in Gyeongsangnam-do and Gangwon-do, respectively, relatively diverse species were considered to be distributed in these areas. Comparatively, in Jeollabuk-do only 36 species were found, whereas in Chungcheongbuk-do and Jeju Island 39 species were found. The number of individual Sphingid moths surveyed in Korea was 21,414. With regard to the number of individuals per species, Ampelophaga rubiginosa was highest, at 2,483, followed by Theretra japonica (1,716), Callambulyx tatarinovii (1,457), Acosmeryx naga (1,340), Rhagastis mongoliana (1,191), Marumba sperchius (1,083), and Dolbina tancrei (1,072). By region, the largest number of individuals was surveyed in Gyeongsangnam-do (4,595), followed in order by Gangwon-do (3,648 individuals), Gyeonggi-do (3,011), Jeollanam-do (2,454), and Jeju Island (2,382). Over time, the highest numbers-in this case 9,498 individuals in 52 species-were identified after 2000. In the 1990s, there were 6,027 of 49 species identified; in 1980s, 4,332 individuals of 49 species were identified; and, in the 1970s, 937 individuals of 45 species were identified. It was confirmed that more species and individuals were identified as time passed. The appearance of Sphingid moths by month was found to be as relatively diverse, as they appeared from February to November. Overall, southern species, including M. saishiuana, Cephonodes hylas, Acosmeryx castanea, T. nessus, and T. clotho, which mainly inhabit Jeju Island and the southern part of Korea, have increased over time from the past to the present. Species inhabiting the middle or northern parts of the Korean Peninsula or the entire country of Korea, including Sphingulus mus, Ambulyx schauffelbergeri, and Mimas christophi, show decreases over time.】

We investigated feasibility of a compact, low-cost, laser-induced breakdown spectroscopy (LIBS) device made up of a Q-switched, diode-pumped, solid-state laser and a nongateable miniature spectrometer for the classification of edible salts. LIBS spectra of edible salts from 12 different geographic origins were obtained by this compact LIBS device. The detection limits of the compact LIBS device for potassium, magnesium, and calcium with effective discrimination power were sufficient to classify the edible salts. The classification model was developed by the multivariate analysis of the LIBS spectra. The comparison of the LIBS results with inductively coupled plasma-atomic emission spectroscopy analysis indicates that the clustering of principal component scores was well dominated by chemical compositions of the salts. The cross- and external validations of the classification model showed reasonable performance (98.3 and 87.5% correctness, respectively). Our results indicate that rapid classification of edible salts can be realized by a compact, low-cost LIBS device.

The qualitative and quantitative analysis of the different arsenic species in Korean oyster samples was performed to provide the vital information of food safety of the marine sample in terms of the arsenic species. Korean marine samples, oysters, were obtained from nine sites in the western and southern areas of South Korea. Inductively coupled plasma mass spectrometry (ICP-MS) was used to measure the total arsenic. The different arsenic species in the oyster were separated by ion chromatography (IC), and then detected by ICP-MS. Extraction of arsenic species was performed with the mixed solvent of the methanol:water (3:1). The extraction efficiency of arsenic species (the ratio of total amount of the different arsenic species to the total arsenic in the oyster) for nine oysters was approximately 73–81%. The major arsenic species in the oyster was arsenobetaine, and its concentration in the samples was in the range of 7–16 mg/kg that was more than 90% of the total organic arsenic in the oyster. As(III) was not generally detected while the trace As(V) was detected in most oysters.

The high content of potassium in molasses limits its usage as a raw material for stock feed. Moreover, its high viscosity makes it difficult to develop an efficient removal process. In this study, ion exchange and solvent extraction experiments have been performed to investigate the removal of potassium from a mixture of molasses with water. Cationic exchange resins (AG50W-X8 and Diphonix) showed a high loading percentage of potassium but the occurrence of breakthrough in few bed volumes was a drawback to the industrial application. Among the cationic extractants (D2EHPA, PC 88A, Cyanex 272) tested in this study, saponified PC 88A was found to be the best extractant for the removal of potassium. Batch simulation studies on a three stage counter current extraction confirmed that 85% of potassium was removed from 50 wt % molasses solution in water by using saponifed PC 88A.

Solvent extraction of Fe(III) from chloride solution by using a mixture of D2EHPA (Di-(2-ethylhexyl)phosphoric acid) and TBP (Tri-butyl phosphate) and the reductive stripping of Fe(III) from the loaded organic were investigated. Quantitative extraction of Fe(III) from the solution (Fe concentration = 90 g/L) was accomplished in two cross-current extraction stages by using the mixture of D2EHPA and TBP. In order to facilitate the stripping efficiency, a reductive stripping method was employed by using H2SO3 or Na2SO3 as a reducing agent. The addition of H2SO4 into reducing agents led to improvement in the stripping efficiency while high concentration acid would suppress it. Both of the mixtures of H2SO4 + H2SO3 and H2SO4 + Na2SO3 showed good efficiency for the stripping of Fe(III), while the latter was recommended as the stripping solution based on the economics and experimental condition.