We demonstrated that a microchip with a wedge-shaped micro space fabricated by polydimethylsiloxane (PDMS) has a potential application for particle size-distribution analysis. The fabrication of the microchips was achieved using a wedge-shaped structure as a template, which was formed by a Digital-light processing (DLP) 3D-printing technique. An approach for evaluating the particle-size from the settling distance of each particle in the wedge-shaped micro space allowed us to design a simple particle detection device consisting of an inorganic electroluminescence sheet, the microchip and a line charge-coupled device (CCD) sensor. The particles detection system, based on the transmitted light intensity, was successfully applied to simultaneous measurements for the particle size of glass beads. The obtained particle size was almost identified with that measured with a microscope.
Dipeptides are expected to improve the physical properties of amino acid, to have a new physical description and a physiological function. However, there was almost no practical method for a comprehensive analysis of dipeptides, and there were only few reports that examined those existences, behavior or functions. In the present study, we developed a comprehensive analytical method for dipeptides, using pre-column derivatization coupled to reversed-phase high-performance liquid chromatography/electrospray ionization tandem mass spectrometry (LC/MS/MS). Dipeptides samples were derivatized with phenyl isocyanate (PIC), which is able to react under the mild condition to the free amino group. The resulting typical derivatives were analyzed by tandem mass spectrometry and specific cleavages in the collision induced dissociation (CID) were observed. These fragmentation patterns have been enabled for practical analysis combined with the predicted selected reaction monitoring (pSRM), precursor ion scan or constant neutral loss scan. With these developed methods, we demonstrated to be able to show dipeptide profiles of food samples, such as cheese and wine.
For the sake of rapid and convenience analysis of trans fatty acid components, the authors developed a reaction field for thermally assisted hydrolysis and methylation-gas chromatography (THM-GC) capable of achieving highly efficient methylation of the components. At first, a trilinolenin standard sample was subjected to THM-GC in the presence of an organic alkali reagent, trimethylsulfonium hydroxide (TMSH) or trimethyl(trifluoro-m-tolyl)ammonium hydroxide (TMTFTH), to investigate the reaction behavior of fatty acid components. As a result, although cis-trans isomerization of the fatty acid components occurred during the THM reaction for both reagents, the use of TMTFTH proved to suppress the isomerization significantly. Then, the optimization of various reaction conditions in the presence of TMTFTH lead to a reduced cis-trans isomerization rate (0.12 %); the THM temperature and the ratio of the amount of the reagent to the sample were set at 180 °C and 40 times, respectively. Furthermore, THM-GC equipped with the developed reaction field was applied to quantitative analyses of trans fatty acid components in edible oils and fats, such as shortening and margarine. The obtained values coincided with the reference values, suggesting that the THM-GC method was able to be used for rapid and convenient determinations of trans fatty acid components.
A ammonia-treated polymer solution was prepared by adding 4.2 mL of 5 M ammonia to 0.1 g of poly (glycidyl methacrylate) dissolved in 20 mL of acetone. The polymer-immobilizing absorbent was prepared by the treatment of a cotton ball having no metal ion adsorption feature with the ammonia-treated polymer solution. The adsorption and elution behaviors of the adsorbent to the samples of various elements were examined by ICP-OES, and the specific adsorption values of platinum(II), gold(III), and mercury(II) were found. Also, regarding other elements in a multi sample, not absorb to the adsorbent. Platinum(II), gold(III), mercury(II) adsorbed on the adsorbent could be eluted with 1 M hydrochloric acid at 93 %, 52 %, and 90 %, respectively. Multicycles of adsorption and elution operation are also possible. The method shown in this study is expected to apply to the separation and recovery of precious metals from urban mines where cost effectiveness and environmental impact are important.
An alkylated azo compound (SB6) with an n-hexyl group into 1-phenylazonaphthalene-4-ol was newly synthesized, and its thermal behaviour was investigated by differential scanning calorimetry (DSC) and polarized optical microscope (POM) observation. After melting, the SB6 underwent a supercooled state in the cooling process, and showed an exothermic peak of 27 kJ mol−1 at 15°C in the subsequent heating process. Powder X-ray diffraction (XRD) patterns revealed that the exothermic peak was accompanied by the crystallization. These results indicated that SB6 exhibited cold crystallization. In addition, the activation energy of the cold crystallization was confirmed to be 60 kJ mol−1.
Attenuated total reflectance far-ultraviolet (ATR-FUV) spectroscopy can be used to investigate the electronic excitation absorption in various materials. Recently, ATR-FUV studies regarding inorganic semiconductor powders and ionic liquids have been progressing. Newly developed systems enable spectral measurements under conditions where materials exhibit their functionalities. For optical functional materials, such as titanium dioxide, an external light-irradiation system was developed. Upon irradiation with UV and visible light, the spectral intensity in the FUV region was changed. In addition, strong relationships between metal modified titanium dioxide and its photocatalytic activity were revealed. Another developed system that operates under electrochemical conditions was applied to the investigation of ionic liquids. As a result, reversible spectral changes depending on the applied voltage were measured, and the interaction between the iodide anion and the imidazolium cation was revealed. These new ATR-FUV systems can be used for other functional materials that contribute to our understanding and device design of materials.
In analytical chemistry, the adsorbent plays many roles, such as in the adsorption or concentration of a sample to be measured or in the removal of unnecessary substances that are not to be analyzed. A separation and purification method in which an adsorbent is filled in a tube, a gas or liquid serving as a carrier is sent into the tube, and the adsorption and desorption of analytes and other components are continuously repeated is called chromatography. In chromatography, dynamic mass transfer is carried out between a carrier gas or solvent, a sample component, and an adsorbent. Therefore, the shape and size of the adsorbent have a great influence on the analysis performance. The authors have focused on monolithic silica, which has a different shape from the spherical particles commonly used in chromatography, and have promoted its use in chromatography. In this article, we will introduce the structural characteristics of monolithic silica and the development status of monolithic silica for the separation and analysis of various compounds ranging from gas components to biopolymers.
This paper suggests an improved internal standard method for the flame atomic absorption spectrometry of nickel in a steel sample. The variation of iron absorption was greatly compatible to that of nickel, and then iron-matching calibration standard solutions were conventionally required for precise analytical results. To correct for a varied concentration of iron in a sample solution, phosphoric acid was added into the solution. The absorption caused by phosphorus oxide was simultaneously measured with the absorptions of nickel and iron by using an atomic absorption spectrometer equipped with a continuous light source and an echelle grating system. The improved method was used to quantify nickel in several steel samples containing about 85 to 98 mass% of iron.