Temporal-special distribution of dissolved major anions at 64 sites in headstreams without any direct human activity of the Shikoku mountainous area in Japan was investigated from autumn to early winter from 2009 to 2012. It was proposed in this work that sulfate ion (SO₄²⁻) concentration in the headstream water was differentiated into fractions of geologic environment and atmospheric fallout consistent with long-range transportation and domestic origin. The geologic environment SO₄²⁻ was obtained to be 2-3 μmol L⁻¹ in metamorphic rock belts, limestone and granite areas, 21 μmol L⁻¹ in sedimentary rock belt, and 10 μmol L⁻¹ in chert areas. In the sites above phase boundary layer height and with less effect of domestic origin, a correlation of the fallout fraction of SO₄²⁻ increased exponentially against the elevation between the sampling site and the highest point in the catchment area. It was considered that the accumulation phenomena of SO₄²⁻ was caused by deposition from the upper atmospheric layer accumulating PM_2.5. The domestic origin of SO₄²⁻ under 480 m alt. of sampling site was increased in the order of categories faced to East Seto > West Seto > Bungo Channel > Kii Channel > Tosa Bay.

Ginger is a spicy vegetable with an antioxidant capacity. 6-Gingerol and 6-shogaol are thought to be the major compounds contributing to its antioxidant activity and their content changes during the heating process. We investigated changes in 6-gingerol and 6-shogaol concentrations using LC-UV and changes in antioxidant capacity using ESR during the heating process. The effects of four cooking processes, namely microwave heating, roasting, boiling, and steaming of ginger, were evaluated. The separation of 6-gingerol and 6-shogaol was achieved using an ODS column with a detection wavelength set at 228 nm for the LC-UV determination. The ESR measurement evaluated antioxidant activity as radical scavenging activity against OH radicals and O₂⁻ radicals. In the boiled and steamed processes, 6-gingerol decreased and 6-shogaol increased. Moreover, the study showed that the conversion of 6-gingerol to 6-shogaol occurred following heating. In addition, all the ginger samples, including a non-heated sample, showed strong O₂⁻ radical scavenging activity. These results suggest that ginger exhibits antioxidant activity by scavenging O₂⁻ radicals more than OH radicals.

Factor analysis (FA), one of the multivariate analysis methods frequently employed in chemometrics, is a powerful tool for extracting physical/chemical information of pure components from the analytical data of the mixture of the components. Although FA has been applied mainly to the quantitative analysis in the field of analytical chemistry, its application to the qualitative analysis has been limited. This article aims at introducing FA to the qualitative analysis for determining the speciation/structure of individual chemical species/compounds by X-ray absorption spectroscopy (XAS). The fundamental concept for extracting physically/chemically meaningful information from XAS-FA is described, and some reported studies using XAS-FA for the qualitative determination of chemical species/compounds are summarized.

Photoacoustic imaging (PAI) is an imaging technique in which near-infrared light is irradiated onto a biological tissue and the resulting ultrasound waves are converted into an image. The mechanism of optical excitation and ultrasound detection enables high-resolution imaging in depths of several centimeters. When exogenous dyes are accumulated at specific sites as PA probes, it is possible to obtain site-selective images. Recently, target-responsive PA probes have been developed, but there are still few examples of their design. The author has studied the structure-property relationship of platinum(II) diradical complexes that absorb near-infrared light, and reported the behavior of near-infrared light absorption in response to pH and hydrophobic cavity, as well as their mechanisms. Furthermore, the author has found that platinum(II) diradical complexes can be used as photothermal therapeutic agents with high photostability. In this article, PAI and PA probes are explained, and an explanation is given on the progress of research on platinum(II) diradical complexes, which are the subject of our research, then an introduction is proved of research results from one of the author’s studies, a platinum(II) diradical complex as a PA probe with signal-switching and therapeutic functions.

New pH electrodes with a self-cleaning function were developed to reduce the maintenance burden on users. Since pH is measured continuously in factory wastewater, various organic compounds and microorganisms cause problems such as contamination of the pH-responsive glass and clogging of the liquid junction. Therefore, regular cleaning and calibration are necessary to ensure stable and accurate measurements. The typical way to deal with contamination is for workers to perform periodic maintenance such as cleaning and calibrating the electrodes, but this poses a problem in that it places a heavy burden on workers and poses a large safety risk. In order to solve these problems, pH electrodes with a self-cleaning function were developed by coating a pH-responsive glass membrane with TiO₂. The electrode has a built-in UV-LED. The internal liquid is the water-insoluble gel that contains KCl granules and is highly transparent to ultraviolet light, and the liquid junction is an open junction to eliminate clogging. Furthermore, the relay box with a constant current source for lighting the LED and accessories for installing electrodes were also developed. The electrode has basic performance comparable to that of conventional pH electrodes, and was able to remain maintenance-free for a certain period of time even during on-site tests where there is a heavy maintenance burden due to organic contamination. These results are expected to make a significant contribution to industrial associations and industry. It is also expected to greatly contribute to the development of pH electrode technology in the future, and is expected to be applied to pH electrodes for laboratory applications such as medical, pharmaceutical, and biotechnology, as well as to optical sensors.

In Japan, an analytical method based on LC/MS/MS has been introduced as the official analytical method for diarrheal shellfish toxins (okadaic acid (OA), dinophysistoxin-1 (DTX1), dinophysistoxin-2 (DTX2), and their esters) in bivalves. In this study, a simplified method was developed by applying solid phase extraction using hydrophilic-lipophilic packing materials, wherein the saponified bivalve extract loaded into the cartridge was eluted without a cleanup process. In an analysis of a scallop sample, the impact of the matrix effect in LC/MS/MS measurements on the observed analytical results was evaluated by comparing the peak intensities of OA, DTX1, and DTX2 in the processed solution using the present method with those in methanol; the rate of change ranged from –1 to 6 %, and no significant change was observed. Then, the validation parameters (trueness, repeatability, intermediate precision, selectivity, and limits of quantification), for which performance criteria were established by the official analytical method were evaluated, and all observed results met the criteria. The trueness of the method was further evaluated by analyzing a scallop-certified reference material, and analytical results corresponding to the certified values were observed. The bivalve sample was then expanded to include clam, oyster, and mussel samples. The impact of the matrix effect on LC/MS/MS measurements was evaluated as described above, and satisfactory results ranging from –16 to –1 % were observed. The trueness and repeatability were further evaluated, and the results met the individual criteria of the official analytical method. The results obtained in this study indicate that the present method offers highly accurate analytical performance for diarrheal shellfish toxins in bivalves.

Fragrances consist of several hundred different ingredients (hereafter referred to as “fragrance components”) and impart the function of fragrance to fabric care products such as fabric softeners. In fragrance quality control, it is necessary to comprehensively extract and analyze fragrances composed of multiple components to confirm that they are manufactured with the designed fragrance content and to quickly identify the cause of production problems. Although liquid-liquid extraction is a commonly used fragrance extraction method, it is difficult to extract fragrances from fabric softeners containing high concentrations of surfactants because of emulsions formed by the surfactants. In this study, an extraction method using a siliceous soil column was investigated for fabric softeners that form emulsions during liquid-liquid extraction. After considering the sample loading method to the column and the extraction solvent type, a quantitative analysis method with good recovery and repeatability was developed by combining the method with GC/MS measurement. This method enabled an accurate determination of the fragrance content of fabric softeners.

Magnesium is the lightest of all the commonly used metals, which also has the best strength-to-weight ratio, thus its alloys have been developed and applied to various kinds of transport facilities and devices. Therefore, the Japan Society for Analytical Chemistry has developed new certified reference materials of magnesium (JSAC 0141, JSAC 0142, JSAC 0143) and magnesium alloys (JSAC 0151, JSAC 0152, JSAC 0153, JSAC 0154) for the analysis of their chemical components as a first case in Japan. Interlaboratory testing was carried out with the participation of 17 laboratories, followed by the ordinal statistical analysis with rejection of the outliers in prior. The final certified elements were 3-7 elements for magnesium CRMs and 6-10 elements for magnesium alloy CRMs. They are intended to be used for instrumental calibration and validation of analytical results in component analysis and impurity analysis.

Regarding chlorinated paraffins that have attracted attention recently, we conducted a comparative study of analytical methods for medium-chain chlorinated paraffin (MCCP). To facilitate a comparison of analytical methods for MCCP, an MCCP composite was prepared by mixing fixed amounts of alkanes with 14 to 17 carbon atoms and then reacting chlorine was used as an analytical sample. Separately, a common quantitative standard descripted homolog compositional ratio was prepared, and a collaborative analysis was conducted for the 19 participating laboratories. Participating laboratories reported MCCP analytical results using liquid chromatography-, gas chromatography-, and thermal desorption-mass spectrometry. As a result, the total amount of MCCP was reported to be between 0.34 g g⁻¹ and 1.34 g g⁻¹, with a coefficient of variation of approximately 42 % for all the participating laboratories. Although the abundance ratio of MCCP in the quantitative standard was biased toward low carbon numbers, we were able to understand the trends of certain analytical methods, and also to evaluate the MCCP homolog compositions in this candidate reference material (the analytical sample). By continuing this activity, we hope to solve further problems with analytical methods for MCCP.