This article presents a sensitive and straightforward colorimetric chemosensor for the determination of phosphate ion utilizing curcumin nanoparticles (CUNPs) as the sensing system. The color of as-prepared CUNPs can be changed from yellow to orange upon adding iron(III) ions due to the formation of a complex with CUNPs. However, in the presence of phosphate ions, iron(III) ions prefer to bind to phosphate ions and, subsequently the color of CUNPs is selectively recovered because of releasing the iron(III) ions from the CUNPs-iron(III) complex. Therefore, in this work the selective color changing of the CUNPs-iron(III) system upon the addition of phosphate ions was used for the quantitative sensing of phosphate ions. Various factors, such as the pH, concentration of iron(III) and volume of CUNPs, were examined and the optimum conditions were established. A linear calibration graph over the range of 10 – 400 ng mL⁻¹ for phosphate (r = 0.9995) was achieved using the optimal conditions. The limit of detection (LOD) of the proposed method for phosphate was 7.1 ng mL⁻¹ and the relative standard deviation (RSD) for measuring 50 ng mL⁻¹ of phosphate was 3.7% (n = 8). The developed method was applied for the measurement of phosphate in water, soil, and bone samples. Satisfactory results were obtained.

The mutual separation of lanthanides has been studied by multi-stage extraction using an extractant, DGA (diglycolamide) compounds. N,N,N′,N′-tetraoctyl-DGA (TODGA) has a high extractability to lanthanides and a relatively high separation factor (SF) between Dy and Nd (SF of over 20) from HNO₃ media. Complete separation with such SF values can be achieved by multi-stage extraction. Less information on multi-stage extraction compared to batch extraction has been presented up to now. We thus conducted a basic study. By confirming the experimental data to be identical to calculations, the sample solution including both metals was employed for batchwise multi-stage extraction. Ninety-seven percent of Dy with under detection limit of Nd could be recovered into the organic phase from Nd with a ten-times higher concentration than Dy using the condition, 0.1 M TODGA/n-dodecane and 0.3 M HNO₃ by the multi extraction of 9 × 9 stages for organic and aqueous phases.

This paper describes a method for obtaining information that can contribute to individual identification from a single hair colored with a hair dye product using a combination of surface-enhanced Raman scattering (SERS) and X-ray fluorescence (XRF) analyses. SERS and XRF spectra of single hog hairs colored with several commercially available hair dye products were measured. SERS spectral patterns tended to be different depending on the hair dye products used for hair coloring. However, SERS spectral patterns of single hog hairs colored with different hair dye products that would produce similar types of dyes were similar. By performing XRF analysis, characteristic metallic elements originating from some hair dye products were detected. Therefore, XRF can contribute to identifying the difference among colored hairs that cannot be identified only by SERS. SERS and XRF analyses of a single shed hair can contribute to individual identification used in forensic science.

Cysteine (Cys), as one of the important amino acids, plays a vital role in various physiological and pathological processes. Hence, it is meaningful to develop a convenient and sensitive detection method. Herein, a novel BODIPY-based fluorescent probe (BDP-DM) was developed, which had a higher selectivity for Cys than other amino acids, including homocysteine (Hcy) and glutathione (GSH). Ultimately, we concluded that the BDP-DM probe could be used to successfully detected intracellular Cys in living HeLa cells.

Nano-Cu modified Cu (nano-Cu/Cu) and nano-Cu modified graphite (nano-Cu/C) electrodes were prepared by depositing a thin layer of copper nanoparticles on a Cu wire or graphite electrode. Chronoamperometric and cyclic voltammetry techniques were applied to deposit the nanoparticles. The effects of Cu²⁺ concentration, deposition time, number of scan cycles, and scan rate were studied to determine the optimum conditions of the experiment. The applications of both electrodes in the COD analysis were performed using glucose and glycine as the models. The voltammetry of a mixture solution of glucose (mg/L) and glycine (mg/L) in 0.075 M NaOH solution showed an oxidation peak at +0.68 V vs. Ag/AgCl. Good stability of this peak current was shown with relative standard deviations lower than 3% for 10 measurements. Amperometric determination of COD at this potential showed excellent linearities at both nano-Cu/Cu and nano-Cu/C electrodes (R² = 0.997) as well as good precision and accuracy with estimated detection limits of around ∼9 mgO/L for both the developed electrodes. Validation using the conventional COD measurements showed that the measurements achieved the average values of 92.58 and 87.86%, respectively, for nano-Cu/Cu and nano-Cu/C electrodes. Furthermore, comparison with the theoretical COD value achieved 94.90 and 89.87%, respectively, for nano-Cu/Cu and nano-Cu/C electrodes. The results indicated that both electrodes are suitable for practical application in COD determination.

In the present study, the adsorption of glucose oxidase (GOD) to a mesoporous aluminum oxide (MAO) film was examined with in-situ neutron reflectometry (NR) measurements. The MAO film was deposited on a cover glass slip and a Si disc, and its pore structure was characterized by X-ray reflectometry (XRR) and NR. The Si disc with MAO film was applied for an in-situ NR experiment, and its NR profiles before/after adsorption of GOD were continuously measured with a flow cell. The results indicated that the negatively-charged GOD molecules hardly penetrate into the narrow pore channel (pore diameter = ca. 10 nm) with opposite surface charge.

Hydrophobic and volatile flavor molecules can be encapsulated inside cyclodextrins (CyDs). Inclusion complexes are frequently used in solid or dispersed states in preserved food and cosmetics. In this study, the solid-state structures of spray-dried inclusion complexes of l-menthol in α-CyD and β-CyD were analyzed using ¹³C solid-state NMR and vibrational circular dichroism (VCD). The NMR signals of l-menthol and CyDs were identified in the physical mixture and the l-menthol inclusion complex of α- and β-CyD. The NMR signal of the isopropyl–methyl group of menthol in the α-CyD inclusion complex exhibited a large low-field shift, which suggested a steric hindrance between menthol and α-CyD. VCD exhibited specific changes in the intensity of bands corresponding to C–C vibrations in α-CyD and O–C stretching vibrations in l-menthol. Our results indicated that l-menthol specifically fitted the narrow space within α-CyD. The combined solid-state NMR and VCD analysis provided structural insights into the flavor inclusion complex in the solid-state.

A new sensitive, simple, rapid, reliable and selective fluorometric method for the determination of pantoprazole (PAN) in human plasma and a pharmaceutical formulation has been developed. This technique is based on a quenching effect of silver nanoparticles (AgNPs) on the emission intensity of a fluorescent probe, terbium(III)-1,10-phenantroline (Tb(III)-phen) complex (due to a fluorescence resonance energy transfer (FRET) phenomenon between the Tb(III)-phen complex and AgNPs), and then restoring the fluorescence intensity of the Tb(III)-phen-AgNPs system upon the addition of PAN (turn off-on process). The effects of various factors on the proposed method including time, temperature, pH, order of the addition of various reagents and the concentration of AgNPs were investigated. Under the optimal conditions, a good linear relationship between the enhanced emission intensity of the Tb(III)-phen-AgNPs system and the PAN concentration was observed in the range of (10 – 1000) × 10⁻⁸ M. The limit of detection (LOD) and the limit of quantitation (LOQ) were 7.2 × 10⁻⁸ and 24.2 × 10⁻⁸ M, respectively. Also, the interferences of some common interfering species on the fluorescence intensity of the system were investigated. This simple and sensitive method was successfully applied for the determination of PAN in spiked human plasma samples and in its capsule formulation. The analytical recoveries were in the range of 88.54 – 101.33 and 90.07 – 98.85%, respectively.

A cost-effective flow-batch analysis approach with colorimetric measurement has been developed for sulfide ion determination in turbid water samples without using a conventional pump and valve. Under an acidic condition, sulfide ion was converted to hydrogen sulfide gas and liberated out from other complicated matrices. The porous membrane-based diffusion scrubber was utilized as a gas trapping unit for hydrogen sulfide gas separation/preconcentration. From the correlation of sulfide ion concentration and disappearance of sodium nitroprusside reagent detection by using a homemade LED-photodiode based colorimetry, a linear relationship of sulfide ion concentration and absorbance can be obtained with relative standard deviation (%RSD) less than 5%. The limit of detection was 5.6 μmol L⁻¹. The proposed system was applied for sulfide ion determination in wastewater samples with the recoveries of 91.0 – 105.2%. The proposed system is a robust setup and able to handle turbid water samples without a sample filtering step.

Novel miniaturized poly(vinyl chloride) matrix membrane sensors based on screen-printed carbon electrodes and responsive to bisphenol S (BPS) were formulated. Polymeric membranes are based on an ion-pair complex of BPS anion with an Aliquat 336S counter cation. A solid conductive contact of multi-walled carbon nanotubes (MWCNTs) was used on screen-printed carbon platforms. After drop-casting and drying of the MWCNTs on a carbonaceous substrate, it was coated with a layer of polymeric poly(vinyl chloride) PVC sensing membrane containing the recognition complex. Prepared electrodes revealed a near-Nernstian response towards BPS with a –28.2 ± 0.8 mV/decade anionic slope, 0.02 μg/mL detection limit and 2.5 × 10⁻⁷ – 1.0 × 10⁻³ M concentration range (r² = –0.9994). Signals were recorded in a 30 mM HCO₃⁻/CO₃²⁻ buffer, pH 10, with fast response times <10 s. A suggested sensing system was effectively applied in the quantitative determination of diminished BPS levels released from plastic bottle samples, and obtained results were statistically assessed against a chromatographic HPLC independent reference method.

An acriflavine-graphene oxide (GAF) supramolecular assembly has been prepared from water-soluble graphene oxide (GO) and a fluorescent dye, acriflavine (AF). Upon binding this non-covalently to the GO, the fluorescence of acriflavine has been “turned off” effectively, competitive binding potential of the sensor substrates such as ATP, ADP, AMP and the pyrophosphate weakens the supramolecular assembly of GAF, which allows the release of acriflavine quantitatively, which also “turns-on” the fluorescence of the dye under UV irradiation. Interestingly, GAF displayed the highest sensitivity towards ATP within the family of adenosine phosphates. We have developed a naked eye detection method for the adenosine phosphates biomolecules. For the first time, acriflavine has been utilized for the sensing of adenosine phosphates in combination with GO, which can be useful for the detection of other biomolecules.

We measured X-ray absorption fine structure (XAFS) and Raman spectra of isopolymolybdates(VI) in highly concentrated HNO₃ solution (0.15 – 4.0 M), which change their geometries depending on the acid concentration, and performed the simultaneous resolution of the XAFS and Raman data using a multivariate curve resolution by alternating least-squares (MCR-ALS) analysis. In iterative ALS optimization, initial data matrices were prepared by two different methods. For low sensitivity of the XAFS spectra to the geometrical change of the isopolymolybdates, the MCR-ALS result of single XAFS data matrix shows a large dependence on the preparation method of the initial data matrices. This problem is improved by the simultaneous resolution of the XAFS and Raman data: the MCR-ALS result of an augmented matrix of these data has little dependence on the initial data matrices. This indicates that the augmentation method effectively improves the rotation ambiguities in the MCR-ALS analysis of the XAFS data.

Here, we present an excellent strategy of unmodified near-ultraviolet fluorescence nitrogen doping carbon nanobelts (NFNCBs) for detecting nimesulide (Nim). After a simple hydrothermal process of uric acid and hydroquinone in DMF solvent, NFNCBs shows the shape of corroded stalactite-like composed of nanobelts aggregates, near-ultraviolet luminescence and a narrowed full width at half maximum. This could improve/change the electronic properties and surface chemical active site, as the result of a sensitive response to Nim. By employing this sensor, the quantitative measurement displays a linear range of 2.0 nM – 100.0 μM with a lower detection limit of 0.21 nM (3σ/k) for Nim. Our work has provided a high selectivity for Nim, which may be capable for pharmaceutical sample analysis in real tablets. Furthermore, the results concerning the recoveries (96.3 – 106.2%) for real sample analysis indicate that this nanoprobe might expand a good avenue to design an effective luminescence nanoprobe for other biologically related drugs.

The triphasic extraction system with two extract phases can be used to separate two materials simultaneously into each phase. In this article, a possible mutual separation of Fe(II) and Fe(III) was studied using the cyclohexane/water/ionic liquid (IL) triphasic extraction system for Fe speciation. For Fe(II) and Fe(III) extraction, 2,2′-bipyridine (bpy) and tri-n-octylphosphine oxide (TOPO) were selected as extractants, respectively. It was suggested that [Fe^II(bpy)₃]²⁺ and Fe^III(TOPO)₄³⁺·3Tf₂N⁻ were extracted into the IL (1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, C₄mimTf₂N) phase and the cyclohexane phase, respectively, and both of the extractants also acted as masking agents. On simultaneous separation using the triphasic system, Fe(II) and Fe(III) were quantitatively extracted into the IL phase and the cyclohexane phase, respectively, and their mutual separation was achieved.

An ultra-sensitive analytical system that can determine the concentration of N-nitrosamines at the ng/L level without preconcentration was used to investigate the contamination, decomposition, and formation of N-nitrosodimethylamine (NDMA) and other N-nitrosamines in water samples during general analytical procedures. A preliminary experiment was performed to estimate the NDMA concentrations in ambient air. Since the air samples contained NDMA at concentrations in the range of 2.0 – 10.7 ng/m³, ambient air was identified as the source of NDMA contamination in water samples. We directly confirmed that the concentration of aqueous 10-ng/L NDMA samples stored in clear glass bottles decreased upon exposure to sunlight. Thus, to maintain the N-nitrosamine concentration, such samples must always be protected from sunlight during sampling. The existence of N-nitrosamines in experimental reagents, such as ranitidine and sodium hypochlorite solutions, was also confirmed, as was the formation of NDMA on an activated carbon solid-phase extraction cartridge.

Geopolymer is the inorganic polymer commonly made from kaolin, clay, fly ash, or slag. Obsidian mineral is the new candidate material for geopolymer formation. Obsidian is a material that used in ancient eras, but nowadays, this function has been replaced by various metals. Obsidian consists of cristobalite and sodium aluminum silicate. Obsidian was reacted with disodium metasilicate (Na₂SiO₃) to form a mineral-based geopolymer. An analysis of the formation mechanism through X-ray diffraction and Fourier transform infrared spectroscopy showed that the geopolymer formation from obsidian takes place in two stages. The first stage is the formation of a geopolymer from a reaction among cristobalite, disodium metasilicate, and amorphous aluminum silicates, whereas the second stage is the incorporation of crystalline sodium aluminum silicate into the former geopolymer structure. Geopolymer is usually utilized to form brick or concrete for an infrastructure purpose, but in this research, the geopolymer is proposed to control the release rate of elements from fertilizer. The result of potassium release test shows that the geopolymer has a slow-release property.

A grey system based on the principle of complementary colors was constructed as an activatable probe for the sensitive and specific ratio-colorimetric detection lead ions (Pb²⁺) in a complex food matrix. This grey system was prepared by mixing purple-red AuNP-capped glutathione (GSH) and green-blue sulfonated pigment green 7 (SPG7), to create the SPG7/AuNP probe. In the presence of Pb²⁺, the strong chelation of Pb²⁺ with GSH could trigger the aggregation of AuNPs, leading to the color activation of SPG7. Hence, the absorbance ratio A_523nm/A_628nm of AuNPs at ∼523 nm and SPG7 at ∼628 nm could be used for highly specific reporting of Pb²⁺ levels with a low detection limit of 0.33 μg/L. Moreover, this probe exhibited promising practical applications in real preserved egg samples with recoveries of 89.2 to 107.5% and relative standard deviations (RSD) in the range of 0.28 to 2.12%, revealing its great potential for harmful substance detection.

This paper describes uncertainty ranges of the analytical values by laser-induced breakdown spectrometry (LIBS), in order to realize an element-based sorting of commercial Al alloys whose chemical compositions are varied depending on the kind. For this purpose, calibration factors and their standard errors between the emission intensity and the content of major alloyed elements were estimated using a series of standard reference materials of Al alloys. From the result of LIBS analysis, Al alloy samples, labeled as A1050, A1100, A2017, A2024, A5052, A5083, and A6061, were actually classified into the kinds of Al alloy for which the chemical compositions have been standardized by the Japanese Industrial Standards. The sorting was successfully conducted, although several of them could not be classified into a particular alloy type. This was not due to the analytical precision of LIBS but due to a similarity of the chemical composition between several types of the Al alloy. For comparison, a similar sorting procedure was carried out using the analytical result by ICP-OES, which gave the same conclusion as the LIBS. In fact, ICP-OES requires sample pretreatment and dissolution and thus cannot be applied to on-site/in-line analysis, whereas LIBS can provide a rapid response of analytical values. Accordingly, the LIBS analysis may be actually applied for sorting Al alloy materials in detail.

The identification of antigens incorporated into immune complexes (IC-antigens) is important for studying the pathophysiology of immunological diseases. Immune complexome analysis identifies IC-antigens by analyzing ICs collected from biological fluids by IC-capturing beads. In this study, we optimized the method to improve its comprehensiveness while maintaining selectivity for IC-antigens by comparing the number of identified peptides (model IC experiment) or proteins (human pooled serum) eluted from Protein G beads using different pH solutions (pH 2.0 – 11.0).

A sensitive, useful and preliminary screening method was proposed to quantitate the containable cannabinoids most commonly included in mineral water and gummi candy products, specifically cannabidiol (CBD), cannabinol (CBN), 11-nor-9-carboxy-Δ⁹-tetrahydrocannabinol (THCA), cannabigerol (CBG), and cannabidiolic acid (CBDA), using liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) for quality evaluations. Based on the electrospray positive ion mode, the limit of detection and the limit of quantification values were 0.2 to 0.5 ng/mL and 0.8 and 2.0 ng/mL. Samples (0.5 g) were diluted by water/methanol (50/50), to which stable isotope internal standards were added; the recovery results appeared in range from 91.3 to 101.2%. This method was applied to evaluate CBD products (6 kinds) from the Japanese market. Our survey found obvious discrepancies between the labeling and the results were overserved in products. In addition, CBN, THCA, CBG, and CBDA were not detected in full-spectrum products that contained various cannabinoids that naturally occur in the cannabis plant. Thus, it is necessary to be able to verify the accurate concentration and impurity in various CBD products from the Japanese market as quickly as possible.