BUNSEKI KAGAKU Abstracts

Water in confinement plays an important role in various industrial and biological processes. In the present work, water was confined in mesoporous silica (MCM-41) and periodic mesoporous organosilica with phenyl groups embedded in silica matrices (Ph-PMO). The structure and the dynamics of water confined in MCM-41 and Ph-PMO were investigated by X-ray and neutron scattering measurements. Water confined in MCM-41 (pore diameter 21 Å) is not frozen upon cooling to as low a temperature as 140 K; however, a tetrahedral-like (ice-like) structure of water is developed in the core of the pores. Water molecules interact strongly with the hydrophilic wall of MCM-41 through hydrogen bonding, whereas in the pores of Ph-PMO with increased hydrophobicity by the phenyl groups embedded in the silica matrices water molecules tend to assemble in the central region of the pores.

A sensor system based on surface plasmon resonance (SPR) in Au films with various thicknesses deposited all around the core of an optical fiber was constructed. The sensor properties of the Au-deposited optical fibers and the performance of the sensor system with a He-Ne laser to a refractivity range (1.33 – 1.54 refractive index unit) were investigated. The structure of the Au-deposited optical fiber was simplified by depositing a Au film on half of the core of the optical fiber. The simplified Au-deposited optical fiber sensor showed improvement of the performance. Metal-deposited optical fiber sensors with Ag, Cu, and Al were also prepared. The sensor properties were investigated based on the reflection properties of these metal films due to SPR, and with their surface characterization by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The response curves of the metal-deposited sensors with Au, Ag, and Al calculated from SPR theoretical equations agreed well with those obtained by the experiment. An oxide layer on the metal film was considered for the Al-deposited sensor. A simple sensor system with a light-emitting diode (LED) light source and a photodiode detector was also developed. The response curves and the properties of the Au-deposited sensor obtained using three LEDs (563, 660, and 940 nm) depend strongly on the wavelength of the incident light and the properties can be controlled by changing the LED emission wavelength. The simple sensor system represents a new SPR-based refractometer with performance almost equal to that of an Abbe refractometer. Ethanol concentrations in various spirits were measured by this simple sensor system and the results compared with those as labeled. An analysis of aniline using an acid-base reaction in a polymer film and a detection of albumin using an antigen-antibody reaction on the Au films of the sensors are reported.

Metallomics is a new area of study in Omics for the purpose of ubiquitously understanding the function and role of a trace element in biological activity. Trace elements are included in the proteins or enzymes concerned with gene expression, signal transduction, and various kinds of metabolic responses; they also gives us a new fact to understand biological phenomenon. Moreover, a new analytical technique is very important because any Metallomics study requires an analysis of the chemical species or the distribution at the simultaneous multielement analysis, and identification of trace elements from a very small amount of biological samples. In this report, we introduce outlines about the relationship between trace-element studies and the onset of the disease from the viewpoint of the protein function and metabolism abnormality of bio trace elements including iron, copper and zinc, which are representative elements in trace-element studies. Finally, we describe analytical studies of bio-metal distributions in diabetic mice by using multitracer and the multiple molecular imaging system, “GREI”, as an example of Metallomics research analyzed by bio-metal imaging.

Large-scale mechanical recycling of waste plastics requires useful sorting techniques. We have developed a high-speed, accurate identifier based on Raman spectroscopy for recycling PP, PS and ABS from post-consumer electrical appliances. It consists of a high-power diode laser (785 nm), a large numeric aperture optical system and a high-speed signal-processing on-board circuit. Small pieces (less than 10-mm square) of the plastics could be identified with a 3-ms measuring time on a conveyor belt (speed, 100 m min⁻¹). The 50 Raman identifiers successfully work in parallel in a practical-scale demonstration facility, and a purity of more than 95% is achieved from shredded plastics at a throughput of 200 – 600 kg h⁻¹. Multivariable analysis using the Mahalanobis distance could reveal a correlation between distortions of the Raman spectra and the weight losses in thermogravimetry to estimate the degradation of the waste plastics.

Lead contamination caused from solder on discarded electronic devices has been reported as an important environmental problem. The dissolution mechanism of lead (Pb) and tin (Sn) from solder should be estimated from the dissolved chemical species. Chemical species of Pb and Sn dissolved from solder in an acid solution could be identified by electrospray ionization mass spectrometry (ESI-MS). Studies were first carried out with inorganic Pb and Sn salts in acid solutions, and referred to as reference solutions. For Pb, species containing hydroxide ion were mainly observed in a reference solution, indicating that Pb does not react with Cl⁻ or NO₃⁻, and may exist as hydroxo or hydrated complexes. On the other hand, the Sn species contained chloride ions showing different behavior from the Pb species for coexisting anions. Second, for solder was dissolved in acid solutions, the solutions were measured with ESI-MS, and dissolved Pb and Sn species were identified. The main species of Pb in the solutions contained hydroxide ions similar to reference solutions, indicating that Pb existed as hydroxo and hydrated complexes. For Sn, although the total concentration of Sn was higher than that in the reference solution, the peak intensities of the Sn species were lower than those in the reference solution. This suggests that the Sn species dissolved from solder in acid solutions existed as non-charged forms or particles, and therefore the Sn species were not clearly detected with ESI-MS. Also, the dissolution mechanism of Pb and Sn from solder in acid solutions was estimated. Finally, the impact of dissolved Pb and Sn on the environment, and thus on humans, was considered. The behavior of Pb and Sn after dissolution from solder may significantly differ, and different treatments should be applied for the recovery and decontamination of the respective elements.

The acid dissociation constants (K_a) of 4-pyridylboronic acid derivatives were determined spectrophotometrically, and the pK_a assignment was performed based on ¹¹B NMR spectroscopy. It was found that both of the boron centers in 4-pyridylboronic acid (4-PyB(OH)₂) and the N-methylated derivative [4-(N-Me)Py⁺B(OH)₂] have strong acidities (pK_a^B = 4.00 and 3.96, respectively), indicating that the introduction of a methyl group into the nitrogen atom of the pyridine ring in 4-pyridylboronic acid has no influence on the acidity of the boron center. Kinetic studies on the complexation reactions of 4-(N-X)Py⁺B(OH)₂ (X = H, Me) with hinokitiol (Hipt) were carried out under pseudo first-order conditions, where the total concentration of boronic acid was much larger than that of Hipt. Both 4-HPy⁺B(OH)₂ and 4-(N-Me)Py⁺B(OH)₂ reacted with Hipt much faster than their conjugate boronate ions (4-HPy⁺B(OH)₃⁻ and 4-(N-X)Py⁺B(OH)₃⁻, respectively), which is consistent with our recent results. The rate constants (k₁) for the reactions of the boronic acids with Hipt increase with an increase of the acidity of boronic acid. The reactivity of 4-(N-Me)Py⁺B(OH)₂, having the strongest acidity (pK_a^B = 3.96), was still higher than the phenyl and pyridyl boronic acid derivatives having pK_a^B = 4.40 – 10.74, which we have examined so far.

JIS K 0102 defines Molybdenum Blue Method as a spectrophotometric determination of phosphate. Molybdo antimonyl phosphate is formed by the reaction of phosphoric and molybdic acids and potassium antimonyl tartrate, which is then reduced by ascorbic acid. The absorbance of the reduced form of molybdo antimonyl phosphate has been known to be higher than those of other complexes. However, the reaction system of the Molybdenum Blue method and the structure of molybdo antimonyl phosphate have not been elucidated so far. To investigate the reaction system and structure, phosphoric and molybdic acids and their derivatives were monitored using electrospray ionization mass spectrometry (ESI-MS) at each reaction step in the procedure. In earlier reports, [PSb₂Mo₁₀O₄₀]³⁻ (m/z 625) was considered to exist as molybdo antimonyl phosphate, but in our studies with ESI-MS this complex was not observed. In a sample solution, a peak at m/z 1033 was identified as [PSb₂Mo(VI)₇Mo(V)₅O₄₀]²⁻; this complex was formed by the addition of both ascorbic acid and potassium antimonyl tartrate. Also, reports suggest [PSb₂Mo₁₀O₄₀]³⁻ (m/z 625) to be first formed and reduced by ascorbic acid. According to our observation by ESI-MS, the formation of molybdophosphate was completed and followed by reduction with ascorbic acid. After reduction, antimony would be attached to the reduced molybdophosphate complex. The complex [PSb₂Mo₁₂O₄₀] is considered neither to be formed in gas-phase nor to be derived from precursors in the solution, but exists as a stable complex. We have thus illustrated that ESI-MS is a useful tool that can be applied to study reactions and metal complexes in solution.

A coulometric determination of chloride ion based on two-step electrolysis involving deposition and dissolution was carried out in two manners. One was the batch method where an Ag net electrode was employed, the other was the flow method, where an Ag wire embedded in polytetrafluoroethylene tube was employed. In the batch method, an aqueous medium and mixed solvent medium of methanol and water were applied. In the case of the mixed solvent medium, the detection limit was improved to be 2.6 × 10⁻⁵ mol dm⁻³ (M), as compared with 9.2 × 10⁻⁵ M in an aqueous medium. However, it took more than 15 min to attain quantitative electrolysis in the batch method. In the flow method, a sample solution of 20 μL was injected, and it took approximately 100 s at 0.01 mL min⁻¹ to attain quantitative electrolysis. The available concentration range of chloride ion was 8 × 10⁻⁵−1 × 10⁻³ M, and the electrolytic efficiency was 97 ± 3%. The detection limit was 7.8 × 10⁻⁵ M.

In this study, a new sampler for the determination of dissolved gaseous mercury (DGM) in seawater was developed. Using this sampler, the analytical procedures from seawater sampling to purge and trap of DGM can be handled without any decanting processes, by which the volatilization loss of DGM from samples is driven. The DGM concentration was a maximum of 27% higher using the new sampler compared to that with other sampling methods that had decanting processes. It was clear that the average loss of DGM caused by the decanting processes was −15 ± 10% (N = 12). Thus, more accurate measurements of DGM in seawater were achieved using the new sampler with no decanting processes. The concentrations of DGM in the surface seawater in the eastern part of the Seto Inland Sea and Minamata Bay were measured using the new sampler. The results indicate that the DGM concentrations in the Seto Island Sea and Minamata Bay were 61 ± 19 pg L⁻¹ and 182 ± 95 pg L⁻¹, respectively. On the basis of the observed data, mercury emission fluxes were calculated using an existing gas exchange model for sea surface. Then, the influences of the loss of DGM due to the decanting processes in sampling on the estimating mercury fluxes were evaluated.

The combination of HPLC, oxidative decomposition by UV irradiation, and cold vapor atomic fluorescence spectrometry (HPLC-UV-CVAFS) was applied to the fractional determination of mercury species, which were contained in biological samples, such as seafood. Firstly, the extraction of mercury species from biological samples was studied, and it was found that 2-mercaptoethanol (2-ME), which has a mercapto group, was an effective extractant. For three certified reference materials, which have the certified values of the CH₃Hg⁺ concentration, extraction by a 2-ME solution and the HPLC-UV-CVAFS measurement were carried out. It was confirmed that the measured values were about the same as the certified values. The same analytical method was applied to real seafood samples. The sum of the CH₃Hg⁺ concentration and the Hg²⁺ concentration in the extraction solution, which was obtained by the HPLC-UV-CVAFS measurement, was about the same as the total mercury concentration obtained by the heat vaporization atomic absorption spectrometry (HVAAS) measurement. Therefore, it is evident that the fractional determination of mercury species in biological samples was favorably performed when the extraction solution obtained by the 2-ME extraction was analyzed by HPLC-UV-CVAFS.

This paper describes the determination of total cyanide and thiocyanate in soil by flow analysis, which uses the cupper chloride-tin chloride reducing distillation (NSOF) method. The apparatus of flow analysis consists of an ultrasonic extraction process of cyanide compounds in soil using a NaOH solution, and an analytical process of total cyanide and thiocyanate ions in the extracted solution. As results to a study of the extraction conditions, when 1.0 g of a soil sample and 50 mL of a 0.05 mol L⁻¹ NaOH solution were used and ultrasonic extraction was performed for 80 s, more than 86% of the total cyanide was recovered. Distillation reagents were used as described concerning the NSOF method, and distillated at 145℃ continuously. Total cyanide was determined by 4-pyridinecarboxylicacid-pyrazolone spectrometry and thiocyanate ion was determined by ferric thiocyanate spectrometry. In the case of JIS K 0170 methods, thiocyanate is not contained in total cyanide. The total cyanide content in soil was calculated by subtracting the thiocyanate ion content from the observed total cyanide content. The proposed method can be used to determine total cyanide and thiocyanate ions in soil, simultaneously.

Patents on analytical laser fluorescence spectroscopy published before June 30, 2012 were examined and analyzed. Patents published at JPO (Japan Patent Office) have been mostly based on invention carried out in Japan. Patents published at USPTO (United States Patent Office) have originated from inventions in USA and abroad, approximately equally. Patents at JPO are predominant in flow systems and microscopy, while those at USPTO are predominant in atoms and molecules and in bio-analysis.