Variations of the ingredients and functionality of Japanese peppermint dried powders by a hot-water treatment were analyzed toward the application of natural green food coloring. Soaking the peppermint powders into hot water led to a release of the polyphenol ingredient, of which the amount increased with the water temperature. Mixing the hot-water treated peppermint powders into a cream as a model food changed the cream’s white color to green color although using untreated powders resulted in showing a brown color. The –a^∗ value in a chromaticity diagram was correlated with both the releasing amount of polyphenol and the remaining ratio of chlorophyll: including the higher ratio of chlorophyll increases the –a^∗ value, but low polyphenol releasing suppressed the increase. Additionally, reducing the polyphenol content in the peppermint powder deteriorated the antioxidant function of peppermint powder; actually, the activity was dropped to 1/10 of the untreated powder. In conclusion, the hot-water treatment is a promising technique to produce a natural green coloring from Japanese peppermint powder, and the resulting color as well as the functionality is possible to be speculated by ingredient analyses presented in this study.

The main compound of green tea beverage behind astringency is a group of polyphenols called catechins. Catechins are considered to be a powerful antioxidant, and by protecting against gene mutation, it is also thought to slow down the aging process and prevent the formation of cancer cells. The rapid analysis of eight kinds of catechins {GC: (-)-gallocatechin; EGC: (-)-epigallocatechin; C: (+)-catechin; EC: (-)-epicatechin; EGCg: (-)-epigallocatechin gallate; GCg: (-)-gallocatechin gallate; ECg: (-)-epicatechin gallate; Cg: (-)-catechin gallate} in green tea beverage by high-performance liquid chromatography (HPLC) with an ultraviolet detector (UV) on a triacontyl bonded silica-gel column has been developed. In addition, a solution of acetonitrile - ethyl acetate - water (10 : 2 : 88, v/v) mixture containing 20mM phosphate was employed as the mobile phase for HPLC separation. This analytical method provides high linearity of the calibration curve as well as both repeatability and reproducibility. The correlation coefficient of the working curve of calibration were estimated to be from 0.9929 to 0.9997 for eight kinds of catechins in the concentration range from 10 mg L⁻¹ to 100 mg L⁻¹. The limits of detection (LOD) calculated on 3σ at 10 mg L⁻¹ were 2.80 mg L⁻¹ for GC, 1.82 mg L⁻¹ for EGC, 0.70 mg L⁻¹ for C, 2.80 mg L⁻¹ for EC, 2.66 mg L⁻¹ for EGCg, 1.81 mg L⁻¹ for GCg, 1.16 mg L⁻¹ for ECg, and 2.75 mg L⁻¹ for Cg. The limits of quantification (LOQ) calculated on 10σ at 10 mg L⁻¹ were 9.33 mg L⁻¹ for GC, 6.07 mg L⁻¹ for EGC, 2.32 mg L⁻¹ for C, 9.34 mg L⁻¹ for EC, 8.86 mg L⁻¹ for EGCg, 6.05 mg L⁻¹ for GCg, 3.88 mg L⁻¹ for ECg, and 9.15 mg L⁻¹ for Cg. Good results, the recoveries were from 87.9% to 99.2% and the relative standard deviations (RSD) were from 2.2% to 4.8%, were obtained in recovery tests by using green tea beverage. This proposed method could be successfully applied to the determination of eight kinds of catechins in green tea beverage.

The solid-phase extraction technique was successfully applied to extract trace uranium and thorium from high-purity gadolinium sulfate to determine the ppt level of those elements by inductively coupled plasma mass spectrometry (ICP-MS). For thorium analysis, the sample was dissolved in hydrochloric acid, adjusted to pH 2 with aqueous ammonia and passed through a column filled with chelate resin having ethylenediaminetriacetic acid as a functional group. For uranium analysis, the sample was dissolved in ultrapure water, adjusted to pH 2 with sulfuric acid and passed through a column filled with anion exchange resin. The adsorbed thorium and uranium were eluted with a hydrochloric acid solution; these eluates were then analyzed by ICP-MS. This method was applied to the high-purity gadolinium sulfates, which was planned for use in a large water Cherenkov detector in Super-Kamiokande in Japan to detect neutrinos. As a result, the proposed methods have achieved limits of quantification of 1 pg g⁻¹, and 4 pg g⁻¹ for thorium and uranium, respectively. Moreover, recoveries of 95 % to 105 % and the removal rate of about 99.97 % or higher for gadolinium in analyte solution were obtained for both elements.

Analysis near the surface is crucial for researching the degradation process, since degradation begins with on external stimulation, such as light and heat. Poly (butylene terephthalate) (PBT) is an engineering plastic with a good balance of mechanical and electrical properties, widely used in automobile components, such as connectors. We report here on a technique to analyze the depth profile of degradation products using matrix assisted laser desorption/ionization time-of–flight mass spectrometry (MALDI-TOF-MS), formed the upon thermal aging of PBT. Pristine and aged sample pieces were shaved into thin films by a microtome for MALDI-TOF-MS analysis of the depth profile. The tensile strength was drastically reduced and the COOH/COOH end-group was increased for bulk samples after aging at 180°C for 200 hours. The degradation proceeds via thermo-oxidation pathway mainly because of the appearance of the (CH₂)₃-COOH/COOH end group in the layers shallower than 155 μm. It was suggested that the decomposition into low-molecular-weight products in the layers shallower than 155 μm affected the decrease in tensile strength. The MALDI-TOF-MS would be useful for the analysis of the degradation process in depth profile.

A continuous-flow analyzer for silicon has been developed and applied to the determination of silicon in industrial material. The sample, prepared as a hydrofluoric acid solution, is injected into an air segmentation of sulfuric acid and silicon tetrafluoride gas is produced in the mixing coil. The silicon tetrafluoride gas is absorbed in a boric acid solution, which is then subjected to a spectrophotometric determination of silicon as blue molybdosilicic acid. All of the required chemical processes are conducted in a closed system, so that a blank value is kept at low levels. The analyzer was successfully applied to determination of silicon at the 0.29 μg g⁻¹ level in Ta₂O₅. It also enabled the determination of silicon in brass, iron and organic reagents.

Acetylcholine (ACh), a cholinergic neurotransmitter, has been widely analyzed by HPLC-electrochemical detection and other methods. However, these method are not durable because it uses a column immobilized with enzymes, such as ACh esterase and choline oxidase, and it does not directly measure ACh because they measure hydrogen peroxide generated by the enzymatic reaction. In this study, we developed an ACh sensor for direct measurement of ACh using an Mg²⁺ ion selective membrane. The sensor showed good quantitative performance in the range of ACh concentration from 1.00 × 10⁻⁴ M - 1.67 × 10⁻¹ M, enabling simple and rapid determination of ACh. By miniaturizing the sensor, quantification was possible from 1.00 × 10⁻⁵ M, which improved the sensitivity and reduced the sample volume. The developed sensor can be incorporated into flow injection analysis and HPLC detectors, and is expected to be used in various fields such as screening of drug candidates, rapid identification of toxicants and muscle relaxants, and measurement of related metabolic enzyme activities.

The copper tubes of heat exchangers used in air conditioning and sanitation equipment have been reported to show type I pitting corrosion due to the synergistic effects of carbon film and water quality. To quantify the carbon film, the inner surfaces of the tubes after degreasing with acetone are dissolved with a mixture of nitric and hydrochloric acid to allow collection and analysis of the attached carbon. However, there are concerns about the difficulty and danger of the conventional procedure. Therefore, a simple method for quantifying carbon film is required. We reported a method for measuring the difference between the corrosion potentials on the inside with attached carbon film and outside with removed carbon film of copper tubes. However, data variation is observed in medium residual carbon, which is thought to be due to uneven carbon film. In this study, we examined the correlation between residual carbon and composition of surface for X-ray photoelectron spectroscopy (XPS) measurement. The results confirmed that the peak of C 1s increased and Cu 2p_3/2 decreased with increasing residual carbon. As the residual carbon and the integrated intensity at C 1s in the same way showed a linear relation, the residual carbon can be determined by the XPS measurement.

Retention of water in human skin is an important function that is performed mainly by low-molecular-weight compounds in the stratum corneum. To understand the retention mechanism, it is helpful to clarify the distribution of these compounds in the stratum corneum by methods such as imaging mass spectrometry (IMS). Especially secondary ion mass spectrometry (SIMS) has high spatial resolution. The aim of this study was to develop a high-resolution method for analyzing the distribution in the stratum corneum of low-molecular-weight compounds, such as amino acids. Skin samples were prepared by the tape stripping method and 20 successive tape-strips were collected at the same skin position. Analysis was performed using TOF.SIMS 5 instrument with Bi₃²⁺ as the primary ion, accelerated at 25 kV. There are three main findings of this study. First, in determining the relationship between molecular weight and the spatial resolution of ions detected from the skin samples, the signal counts of neighbor pixels must be accumulated to obtain a clearer image of high-molecular-weight ions. Second, the present method could reveal the distribution of Serine and Arginine in the skin samples but was unable to obtain a clear image of Lysine. Finally, the depth distribution of the exogenous components could be determined by comparing the results of the 2nd and 20th tape strips.

Ferrous ion (Fe(II)) is known to form a stable [Fe(phen)₃]²⁺ complex with 1,10-phenanthroline (phen) in an aqueous solution. Here, we report on the complex formation of Fe(II) with phen in a nitrobenzene (NB) solution containing sodium perchlorate (NaClO₄). A sample solution composed of 50 μmol L⁻¹ of phen, 5 μmol L⁻¹ FeCl₂ and 50 μmol L⁻¹ of NaClO₄ was prepared. The absorption band of [Fe(phen)₃]²⁺ formed in the NB solution was observed at 510-520 nm. The sample solution was extracted with a 1 : 1 volume of NB and water phases. The NB solution extracted was then measured by ESI-MS with methanol (MeOH) as a mobile phase to characterize the solution state of Fe(II), phen, and NB. [Fe(phen)₃]²⁺, [Fe(phen)₂-MeOH]²⁺, and [Fe(phen)₂]²⁺ were identified. These Fe(II)-related species probably originate from [Fe(phen)₃]²⁺ and partly from [Fe(phen)₂]²⁺ in a NB solution, and cause the broadening of the absorption band at 510-520 nm. In the gas phase, [Fe(phen)₂]²⁺ is predominant, but unstable and tends to form stable adducts with either one molecule of NB or MeOH. And Na⁺ might come from an ESI-MS equipment and adducts with phen. Interestingly, Na⁺ related complexes, such as [Na(phen)]⁺ and [Na(phen)₂]⁺ were also formed in a NB solution in 3 days. In ionization process of ESI-MS, polymerization of phen is easily occurred, and more phen polymerization is promoted with Fe.

Ion exchange resins are widely used to product pure water and in the purification and measurement of substances in various fields. The physical and chemical properties of resins are generally evaluated by a batch method and/or a column method using a lot of resins. In this study, however, the dynamic behavior of ion-exchanging Ca²⁺ for a single grain of strongly acidic cation-exchange resin was evaluated using a multi-pixels array type Ca⁺ image sensor and a micromanipulator. It was found that the Ca²⁺ adsorption occurred in two steps. The dynamic behavior was also simulated by Matlab with a forward difference method based on the experimental model. By comparing the practical measurement and the simulation, the Ca²⁺ adsorption behavior by ion-exchange resin was fully characterized. This method using an ion-image sensor and the Matlab simulation is very useful to evaluate the dynamic properties of sub-millimeter particles.