Spatially offset Raman scattering line-mapping as an adaptive tool ensuring accuracy for determination of component concentrations in tablets with different particle sizes.

Spatially offset Raman scattering (SORS) line-mapping was explored as a versatile tool to examine accuracy variations in compositional analyses of tablets with different particle sizes. SORS spectra collected near the laser irradiation were less representative of tablet composition due to the limited spectroscopic sampling volume, while the signal-to-noise (S/N) ratios of corresponding spectra were higher. On the other hand, SORS spectra at longer offset distances were better representative of tablet composition, while their S/N ratios were decreased considerably. Therefore, the use of only a certain portion of sliced (line-mapped) spectra balanced with the sample representation and S/N ratio could be advantageous to enhance accuracy. Moreover, a group of optimal slice spectra is expected to vary when the particle size of the tablet changes since the characteristics of internal photon propagation also would change. For the overall examination, SORS spectra of 30 Anaprox tablets (composed of 4 constituents including naproxen sodium) with 2 particle sizes (88.4 ± 11.8 µm and 118.9 ± 38.8 µm) were analyzed, and the concentrations of three components in these tablets were determined. A total of 6 cases (3 components and 2 particle sizes) were examined. When the average optimal slice spectra were employed in each case, the errors were lower compared to those using the average of all slice spectra. The demonstrated scheme was versatile to study the offset distance-dependent accuracy variations according to particle size and target component.

Preparation of nickel foam modified by multiwalled hollow spheres of NiCo2O4 as a promising non-enzymatic glucose sensor.

Nickel foam modified by hollow sphere NiCo2O4 particles was successfully prepared via a hydrothermal method using nanosphere SiO2 particles as the hard template for the hollow structure. Characterisation using SEM-EDX and TEM confirmed the structure as multiwalled hollow spheres with an average size of 270 nm, while characterisation using SEM, XRD, and XPS confirmed that the NiCo2O4 particles were attached on the surface of the nickel foam. BET analysis showed that the surface area of the synthesized NiCo2O4@Ni foam was nearly three times higher compared to that of the unmodified Ni foam. Investigation of the NiCo2O4-modified nickel foam as an electrode for the detection of glucose in sodium hydroxide solution showed high linearity of the anodic currents (R2 = 0.99) in the concentration range of 0-2.5 µM with sensitivity of 0.060 mA µM-1 and an estimated limit of detection of 0.060 µM. Excellent stability of the current response was also obtained with a relative standard deviation of 1.51% (n = 10). Furthermore, the developed sensor demonstrates strong applicability for glucose detection in real samples of human blood plasma, making it highly suitable for practical use. The results indicate that the material is promising for the further development of nickel-based sensors.

Intelligent color image analysis of sintered ores for simple and rapid determination of Fe3O4 concentration.

A simple determination of the Fe3O4 concentrations of sintered ores using color images of the samples has been explored. Sintered ore is mainly composed of Fe2O3 (red), Fe3O4 (black), and other white inorganic oxides, so the color of sintered ore could be representative of the relative abundance of the constituents. Two important challenges were addressed to achieve reliable quantitative color image analysis. First, minute dents and bumps (embosses) exist on the sample surface due to inconsistent particle sizes and particle agglomeration, thereby generating dark shadows. Second, small white spots corresponding to inorganic oxide particles were spread throughout acquired images. The white spots yield very high RGB values, which would hamper the translation of the real sample color originating from the iron oxides. Therefore, the segmentations of particle agglomeration-induced shadows and white spots in the sample images were separately executed using Otsu's method and modified fuzzy C-means (MFCM), respectively. Then, color moments and derived variables from the segmented images were employed to determine Fe3O4 concentrations (6.5-10.5 wt%) using extreme gradient boosting (XGBoost). The predicted concentrations from the color analysis correlated well with reference concentrations determined using conventional titration, with a root mean square error of prediction (RMSEP) of 0.39 wt%.

An axially slanted illumination back-scattering Raman scheme for direct determination of component concentration of powder samples housed in a glass container.

For direct and non-sampling determination of the component concentration of a sample housed in a glass container, an axially slanted illumination (ASI) back-scattering Raman scheme that reduces glass background interference has been demonstrated. The strategy was to increase the distance between the spots illuminated by the laser on the glass container and the housed sample in back-scattering measurement. For realization, the laser initially illuminated at a slant through the upper side of the vial wall (sample-unoccupied space) and reach the top of the sample. By this way, fewer number of generated glass photons could be recognized by a detector since they are farther from the focal plane (sample-illumination spot). The concentration of rosuvastatin (2.98-4.14 wt%) in rosulord samples (mixed with five other excipients) was determined using the ASI back-scattering measurement. When the angle of illumination to the vertical axis was 30° and the distance from the center of the laser spot on the glass wall to the center of spot on the sample (DG-S) was 14.9 mm, the sample peaks became more apparent and characteristic due to the reduced glass background. The accuracy of the concentration measurement was superior to that obtained through conventional back-scattering, in which the DG-S was nearly zero. The proposed scheme provides a simple optical setting to suppress the glass background and takes advantage of the sensitivity of Raman analysis through back-scattering measurement, indicating it as an attractive option for through-container analysis.

Identification of geographical origins of soybean pastes using headspace gas chromatography-mass spectrometry by selecting sample-descriptive components with an Incremental Association Markov Blanket.

The identification of geographical origins of soybean pastes using headspace gas chromatography-mass spectrometry was attempted in this study. Since soybean paste was odor-rich, 36 components were identified in the imported and domestic soybean samples. t-Test, variable importance in projection (VIP), and Incremental Association Markov Blanket (IAMB) were employed to select proper components that could effectively discriminate the two sample groups. The discrimination accuracies were below 87.3 % when all 36 components were fed for either LDA, k-NN, or SVM. When the five t-test-selected components or six VIP score-selected components were employed, the accuracies improved to 95.2-96.2 %. The IAMB selected three different components were 3-methylbutanal, 4-methylnonane, and 2,3-pentanedione, and the correlations among their peak areas were not significant. This suggests that these three components were independently relevant for the discrimination. The accuracy obtained using these three components was superior, 97.7 %, as undescriptive and/or redundant components for the discrimination were excluded.

Feasibility of Raman spectroscopic identification of gall bladder cancer using extracellular vesicles extracted from bile.

Extracellular vesicles (EVs), which are heterogeneous membrane-based vesicles with bilayer cell membrane structures, could be versatile biomarkers for the identification of diverse diseases including cancers. With this potential, this study has attempted the Raman spectroscopic identification of gall bladder (GB) cancer by directly measuring the EV solution extracted from human bile without further sample drying. For this purpose, bile samples were obtained from four normal individuals and 21 GB polyp, eight hepatocellular carcinoma (HCC), and five GB cancer patients, and EVs were extracted from each of the bile samples. The Raman peak shapes of the EVs extracted from the GB cancer samples, especially the relative intensities of peaks in the 1560-1340 cm-1 range, were dissimilar to those of the samples from the normal, GB polyp, and HCC groups. The intensity ratios of peaks at 1537 and 1453 cm-1 and at 1395 and 1359 cm-1 of the GB cancer samples were lower and higher, respectively, than those of the samples of the remaining three groups. The differences of peak intensity ratios were statistically significant based on the Mann-Whitney U test. DNA/RNA bases, amino acids, and bile salts contributed to the spectra of EVs, and their relative abundances seemed to vary according to the occurrence of GB cancer. The varied metabolite compositions and/or structures of EVs were successfully demonstrated by the dissimilar peak intensity ratios in the Raman spectra, thereby enabling the discrimination of GB cancer.

Identification of gallbladder cancer by direct near-infrared measurement of deuterated chloroform-extracted organic phase from human bile.

A simple near-infrared (NIR) spectroscopic scheme enabling direct measurement of organic phase extracted from human bile with no spectral interference from the extraction solvent was demonstrated for identification of gallbladder (GB) cancer. This scheme is used to recognize the different lipid contents in bile samples from GB cancer patients using NIR spectroscopy for disease identification. To this end, the extraction solvent should provide an absorption-free NIR region to observe peaks of related metabolite. For this purpose, deuterated chloroform (CDCl3) is uniquely suited as an extraction medium because it has few absorption peaks in the 4380-4100 cm-1 range, where intense peaks for lipids and cholesterol are located. This exploratory study used 37 bile samples (obtained from five normal subjects and nine GB polyp, 11 gallstone, six hepatocellular carcinoma (HCC), and six GB cancer patients). The transmission NIR spectra of the organic phases extracted using CDCl3 in a commercial glass vial were directly measured. The peak intensities of the GB cancer samples were lower than those of the other samples, and the differences were statistically significant, with a confidence interval greater than 99.0%. The lower lipid and cholesterol contents in the organic phases of the GB cancer samples were effectively identified in the corresponding NIR spectra. Therefore, the proposed NIR scheme is simpler and faster than the previous infrared (IR) measurement approach that requires solvent drying to highlight the buried metabolite peaks under a solvent absorption band.

Authentication of ST25 rice using temperature-perturbed Raman measurement with variable selection by Incremental Association Markov Blanket.

A temperature-perturbed transmission Raman measurement was demonstrated for the discrimination of ST25 and non-ST25 rice samples. ST25 rice is a premium long-grain Vietnamese rice with the aroma of pandan leaves and the scent of early sticky rice. Raman spectra of rice samples were acquired with temperature perturbation ranging from 20 to 50 °C, and the variables (intensities of peaks) with greater discrimination were selected from the spectra using Incremental Association Markov Blanket (IAMB) for authentication. The combination of four, seven, and four variables selected from the spectra at 20, 30, and 50 °C, respectively, yielded the highest accuracy of 97.9%. The accuracies in the single-temperature measurements were lower, suggesting that the combination of mutually complementary spectral features acquired at these temperatures is synergetic to recognize the compositional differences between two sample groups, such as in the amylose/amylopectin ratio and the protein constituent.

Geographical discrimination of dried chili peppers using femtosecond laser ablation-inductively coupled plasma-mass spectrometry (fsLA-ICP-MS).

This study presents a method for discriminating the geographical origin of dried chili peppers using femtosecond laser ablation-inductively coupled plasma-mass spectrometry (fsLA-ICP-MS) and multivariate analysis, such as orthogonal partial least squares discriminant analysis (OPLS-DA), heatmap analysis, and canonical discriminant analysis (CDA). Herein, 102 samples were analyzed for the content of 33 elements using optimized conditions of 200 Hz (repetition rate), 50 µm (spot size), and 90% (energy). Significant differences in count per second (cps) values of the elements were observed between domestic and imported peppers, with variations of up to 5.66 times (133Cs). The OPLS-DA model accuracy achieved an R2 of 0.811 and a Q2 of 0.733 for distinguishing dried chili peppers of different geographical origins. The variable importance in projection (VIP) and s-plot identified elements 10 and 3 as key to the OPLS-DA model, and in the heatmap, six elements were estimated to be significant in discriminating between domestic and imported samples. Furthermore, CDA showed a high accuracy of 99.02%. This method can ensure food safety for consumers, and accurately determine the geographic origin of agricultural products.

Feasibility of diffuser-incorporated near-infrared trans-reflectance measurement for quantitative detection of microplastics captured in perfluorocarbon.

A diffuser-incorporated near-infrared (NIR) trans-reflectance measurement is demonstrated for quantitative detection of polyethylene (PE) particles captured in perfluorohexane (PFH, C6F14). PFH effectively captures PE particles through its hydrophobicity and absorbs little NIR radiation, recommending it for use in background-free NIR detection of captured PE particles. A reflective metal disk was used to push the captured PE particles in PFH toward the bottom of the vial that contained the sample, and the trans-reflectance measurement was performed by illuminating NIR radiation from the bottom of the vial at 45o. Reproducibility is limited by the variation in the positions of small PE-particle aggregates at the water/PFH interface and the difficulty in ensuring full NIR sampling (coverage) of large aggregates. An effective way to secure improved reproducibility under these circumstances is illumination of broader and more uniform NIR radiation for measurement. For this purpose, a polytetrafluoroethylene (PTFE) disk was uniquely incorporated as a diffuser for the trans-reflectance measurement. Compared to the measurement with no diffuser, the diffuser-incorporated scheme produced more distinct PE peaks of low-quantity samples (0.1 and 0.2 mg) and enhanced the reproducibility in measurements of all the samples (0.1-4.0 mg of PE). As a result, the correlation between peak intensity and particle quantity was excellent (R2: 0.997), and a limit of detection of 0.07 mg was achieved.

Identification of gallbladder cancer by direct near-infrared measurement of raw bile combined with two-trace two-dimensional correlation analysis.

We demonstrated the utility of direct near-infrared (NIR) bile analysis for the identification of gallbladder (GB) cancer by employing two-trace two-dimensional (2T2D) correlation analysis to recognize dissimilar spectral features among diverse bile samples for potential improvement of discrimination accuracy. To represent more diverse clinical cases for reliable assessment, bile samples obtained from five normal, 44 gallstone, 25 GB polyp, six hepatocellular cancer (HCC), and eight GB cancer subjects were analyzed. Due to the altered metabolic pathways by carcinogenesis, the NIR spectral features of GB cancer samples, including intensity ratios of main peaks, were different from those of other sample groups. The differentiation of GB cancer in the principal component (PC) score domain was mediocre and subsequent discrimination accuracy based on linear discriminant analysis (LDA) was 88.5%. When 2T2D slice spectra were obtained using a reference spectrum constructed by the linear combination of the spectra of five pure representative bile metabolites and employed, the accuracy was improved to 95.6%. The sensitive recognition of dissimilar spectral features in GB cancer by 2T2D correlation analysis was responsible for the enhanced discrimination.

Cooperative combination of LIBS-based elemental analysis and near-infrared molecular fingerprinting for enhanced discrimination of geographical origin of soybean paste.

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 (AC) and Ca (ACa) peaks in the LIBS spectra were used as the inputs for linear discriminant analysis, the accuracy was 95.4%. The accuracy became 92.1%, when the principal component (PC) scores obtained by principal component analysis of the NIR spectra were employed. To enhance NIR discrimination, two-trace two-dimensional (2T2D) correlation analysis was adopted to recognize minute spectral differences. With using the 1st/2nd PC scores of 2T2D slice spectra, accuracy increased to 95.0%. When the ratios of ACa/AC and the 2nd PC scores of the samples were combined together, the accuracy improved to 99.6%.

Screening of gall bladder cancer through infrared analysis of bile and examination of varied bile constituent composition by the disease.

To demonstrate the infrared (IR)-based bile analysis as a reliable screening tool for gall bladder (GB) cancer, we analyzed a sample set of 37 diverse bile samples (five normal, 18 GB polyp, six hepatocellular carcinoma (HCC), and eight GB cancer subjects). Bile samples of normal subjects (control) and HCC patients were newly included to examine if IR-based bile analysis could be expanded to identify HCC. Concentrations of three bile acids and eight bile salts in the aqueous phase samples were determined in parallel and lipidomic analysis of nine lipid classes in the organic phase samples was performed using liquid chromatography-mass spectrometry. Concentrations of bile salts were lower and relative abundances of bile salts were dissimilar between GB cancer samples and remained group samples. Also, the levels of lipids such as phosphatidylcholines and phosphatidylethanolamines were again lower and their relative abundances in the organic phase of GB cancer samples were different from those of other samples. IR spectral features of the aqueous, organic, and amphiphilic aggregate phases were individually characteristic, while not descriptive enough for the thorough identification of GB cancer. Nonetheless, since they were mutually complementary to represent different metabolites in bile, the use of three phase-merged spectra was synergetic to yield the superior discrimination of GB cancer.

Feasibility for SERS-based discrimination of gallbladder cancer from polyp by indirect recognition of components in bile.

The aqueous solution extracted from raw bile juice is composed primarily of bile salts, with lower levels of bilirubin and its derivatives. Among them, the bilirubin and bilirubin-derived metabolites are the only surface-enhanced Raman scattering (SERS)-active components. An analytical scheme indirectly responsive and able to utilize all bile components, including SERS-inactive bile salts, was explored for SERS-based discrimination of gallbladder (GB) polyp and GB cancer. Initially, the surface of a SERS substrate (Au nanodendrite on Ni foil (AuND@NiF)) was covered with an alkanethiol molecule to generate a SERS signal and attract bile components by mutual interaction. For more effective recognition of bile components, 4 independent substrates covered with 4 different alkanethiols with various functional groups (SH(CH2)2CH3, SH(CH2)2NH2, SH(CH2)2COOH, and SH(CH2)2OH) were prepared. The SERS peaks of each substrate clearly varied on interaction with pure bile components as well as aqueous bile samples, and the SERS peaks in each substrate were individually characteristic. When the principal component (PC) scores of spectra obtained using the SH(CH2)2CH3- and SH(CH2)2OH-covered substrates were combined, the k-Nearest Neighbor-based discrimination accuracy was 100%, superior to those (90.6-96.9%) using individual substrates. The use of complementary bile component-induced spectral information provided by the two substrates was responsible for accurate discrimination. On the other hand, when bare AuND@NiF recognizing only SERS-active bilirubin derivatives was used, discrimination was unsatisfactory (accuracy: 75.0%).

Combination of LIBS-based elemental analysis and near-infrared molecular fingerprinting of bile juice to enhance identification of gallbladder cancer.

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 (AMg/ANa) and Na and K peak areas (ANa/AK) in the LIBS spectra of GBC samples were different from those of the remaining samples. Also, the intensity ratios of main NIR peaks differed in GBC. Nonetheless, the use of only element peak area ratio or NIR peak intensity ratio was not sufficient to clearly discriminate GBC. On the other hand, when the ANa/AK values and second NIR principal component scores were combined, the discrimination of GBC from normal/gallstone/GB polyp was substantially enhanced owing to incorporation of both complementary GBC-discriminant spectroscopic signatures.

A weighted twin support vector machine as a potential discriminant analysis tool and evaluation of its performance for near-infrared spectroscopic discrimination of the geographical origins of diverse agricultural products.

A weighted twin support vector machine (wTWSVM) was proposed as a potential discriminant analysis tool and its utility was evaluated for near-infrared (NIR) spectroscopic identification of the geographical origins of 12 different agricultural products including black soybean and garlic. In the wTWSVM, weights were applied on each variable in the sample spectra to highlight detailed NIR spectral features and the optimal weights to minimize the discrimination error were iteratively searched. Then, the weighted spectra were employed to determine the samples' geographical origins using a TWSVM adopting two non-parallel hyperplanes for the discrimination. For the performance evaluation, SVM, TWSVM, and wTWSVM were separately used for the two-group discriminations and their accuracies were comparatively analyzed. When the SVM and TWSVM accuracies were compared, the improvements by using the TWSVM were significant (95% confidence level) for 10 out of the 12 products. Moreover, the accuracy improvements with the wTWSVM against SVM were significant for all the 12 products. In the case of the TWSVM-wTWSVM accuracy comparison, the improvements by the wTWSVM were also significant for 10 products, thereby demonstrating superior discrimination performance of wTWSVM. Based on the overall results, the wTWSVM could be a potential chemometric tool for discriminant analysis and expandable to other areas such as spectroscopy-based biomedical disease diagnosis and forensic analysis.

Axially slanted laser illumination scheme for direct and accurate Raman spectroscopic determination of gemcitabine concentration in freeze-dried gemcitabine injection powder housed in a glass container.

When Raman spectroscopy is employed for a direct in situ determination of ingredient concentration for a product stored in a glass container, minimization of the interfering glass background in the collected spectrum is demanding to secure a more accurate analysis. To meet this request, an axially slanted illumination (ASI) scheme slantingly irradiating laser on the headspace side of a glass container and positioning a detector beneath the container was demonstrated in this study. This ASI scheme was basically designed to increase the distance between the laser illumination spot and detector location to minimize the number of glass photons reaching the detector. The analytical utility of the scheme was evaluated for the determination of gemcitabine concentration (42.9-58.2 wt%) in the gemcitabine injection powder housed in a glass container. Using the ASI scheme, the spectral features of the gemcitabine powder became distinct with only a weak underlying glass background signal. For comparative purpose, when an axially perpendicular offset (APO) scheme perpendicularly irradiating laser on the side wall where the sample was filled was used, the magnitude of glass background was higher, and the most intense gemcitabine peak was largely buried in the glass peak. The accuracy for determination of gemcitabine concentration using the ASI scheme was superior with an error of 0.20 wt%, while 0.33 wt% with employing the APO scheme. Overall, this study demonstrates that the ASI scheme is a potentially versatile Raman spectroscopic tool for fast non-sampling analysis of other products stored in a glass container.

Enhanced identification of defective pre-coated paints on metal through simple temperature-perturbed infrared measurement in conjunction with two-trace two-dimensional correlation analysis.

A promising infrared (IR) spectroscopic method able to effectively identify defective pre-coated metal (PCM), a pre-painted metal panel, has been demonstrated. A temperature-perturbed IR measurement in conjunction with a two-trace two-dimensional (2T2D) correlation analysis was proposed as a strategy for enhancing defect identification. Our objectives were to induce dissimilar temperature-driven structural variations of base paints and added components, to recognize dissimilarities by 2T2D correlation analysis, and to use subsequent 2T2D correlation features to identify sample defects. For the exploratory examination, three defect cases were studied: 1) grey-silver PCMs with and without phosphate epoxy (2.0%), 2) normal and violet colorant-contaminated (0.2%) black PCMs, and 3) normal, violet (0.5%), and yellow colorant-contaminated (0.1%) white PCMs. The IR spectral features of the PCMs collected at 20 and 50 °C were different due to the temperature-dependent structural variations. Initial measurements at 50 °C allowed discrimination of normal and violet colorant-contaminated black PCMs. When using 2T2D slice spectra obtained from 2T2D correlation analysis using the spectra measured at the two temperatures, violet- as well as yellow colorant-contaminated white PCMs were identified, while these were unclear in the measurements at either 20 or 50 °C. The effective capture of dissimilar temperature-driven spectral variations of base paint and colorants (contaminants) by 2T2D correlation analysis was responsible for the improved defect identification.

Feasibility study for simple on-line Raman spectroscopic detection of microplastic particles in water using perfluorocarbon as a particle-capturing medium.

A simple Raman spectroscopic scheme for on-line detection of microplastics (MPs) in water is demonstrated. Instead of using a conventional physical filter for MP separation, perfluorohexane (PFH, C6F14) was deployed as an MP-capturing medium in this study. When PFH was added into a water-filled L-shape tube, it formed a firm droplet at the bottom of the 90° curve due to its strong hydrophobicity and high density. When a tap water sample containing dispersed polyethylene (PE) particles was flowed through the L-tube, the contained PFH droplet effectively captured the PE particles, with an average recovery of 95.9%. Next, for reliable quantitative analysis, it was necessary to measure the entire PE particle captured PFH droplet in Raman spectral acquisition without partial spectroscopic sampling. Therefore, a wide area illumination (WAI) scheme providing a laser illumination diameter of 6 mm was adopted for sampling of the whole droplet. The intensity ratios of PE and PFH peaks in the collected spectra clearly increased with elevated quantities of dispersed PE particles. When samples of PE particles were measured in sea water, which possesses much higher ionic strength than does tap water, the shapes of PE particle-captured PFH droplets did not change, and the accuracy was maintained. Based on these results, the demonstrated analytical scheme is feasible for field analysis; further study is required to strengthen its utility.

Spatially offset Raman scattering line-mapping as a potential tool for particle size analysis.

A spatially offset Raman spectroscopy (SORS) line-mapping scheme was explored as a tool for the measurement of particle size. The proposed scheme is based on the fact that photon migration in powder packing varies as a function of the reduced scattering coefficient, which is directly related to the particle size of the sample. It is known that a smaller particle yields a larger reduced scattering coefficient. Therefore, recognition of the particle size-dependent photon migration (distribution) could be a means to determine the sample's particle size and SORS is a versatile tool for this purpose. Peak intensities acquired along the SORS mapping line are expected to decrease with an increase of the offset distance and the descending slope of the peak intensity can be translated into particle size, for example, a greater slope (steeper intensity decrease) for smaller particles yielding a narrower (denser) photon distribution. For the study, low-density polyethylene (LDPE) and middle-density PE (MDPE) powders with four particle sizes were measured. In each case, the slope of intensity decrease became less steep with the increase of particle size due to the broader photon distribution. A comparative analysis of LDPE and MDPE spectra found that the slope was steeper in the measurement of MDPE powder since the photon distribution was narrower owing to the high particle density. Together, these findings suggest that the proposed scheme is potentially expandable to measure particle sizes of samples with relevant prior calibration and provide useful information on sample composition also for chemical analysis.