This article reviews analytical methods developed to measure trace metal ions quickly by simple operations. To ensure sensitivity and selectivity towards the target metal ions, the techniques utilize the kinetic difference of the dissociation reaction of metal complexes, the interaction between the solid surface and the metal complexes, and the synergistic effect of spectral characteristics with complex formation equilibrium. Examples include quantitative analysis using thin-layer chromatography and enrichment on membrane filters and a visual threshold detection method for trace metal ions using homo-binuclear complex formation systems.

There are a number of surfactant analysis method for environmental samples and cosmetics using high performance liquid chromatography/mass spectrometry (LC/MS). In this study, quantitative analysis method for anionic surfactants was examined by LC/MS and high performance liquid chromatography/tandem mass spectrometer (LC/MS/MS). As a result of the investigation, it was confirmed that the analysis of low concentrations of anionic surfactants is difficult because of significant background, which is caused by the anionic surfactants contained in the mobile phase concentrated on the separation column due to HPLC gradient analysis. Therefore, we developed a method for the determination of anionic surfactants by LC/MS/MS using a switching valve that enables background reduction by a pretreatment column. The method provides good linearity of the calibration curve and seems to be effective in determining the anionic surfactants.

We verified the possibility of discrimination of raw material beans in white bean paste by Sodium Dodecyl Sulfate-Polyacrylamide Gel Electrophoresis (SDS-PAGE) of the protein fractions of white bean paste made from tebo (white kidney beans), butter beans, and baby lima beans, which are the raw material beans used for white bean paste in Japan. We found some characteristic bands in each of the white bean paste samples of tebo, butter beans, and baby lima beans. In addition, those characteristic bands were detected in simulated white bean paste in which the mixing ratio of each ingredient was varied. Although it is necessary to evaluate the usefulness of these markers based on the results of quantitative and statistical analyses in future work, these results suggest that SDS-PAGE could be a potential tool for discriminating the raw material beans of white bean paste.

A simple SPR sensor consisting of a gold-deposited glass rod with a diameter of 2 mm coated with a graphene oxide (GO) overlayer was developed. The concentrations of the GO aqueous dispersions were 0.5 and 5 mg mL⁻¹, and these solutions were used to fabricate two types of sensors by immersing the gold-deposited glass rod sensor for 15 minutes and then drying in air to form a coating layer. The response property of the GO-coated sensors was evaluated using the ethanol aqueous solutions and the sensitivity of the sensor coated with 5 mg mL⁻¹ was slightly improved compared to the unmodified one. On the other hand, the sensitivity to the dilute caffeine aqueous solution was greatly improved. It was found that the sensor with five layers of GO showed the best response and it was possible to detect lower concentrations than the caffeine contained in common beverages. On the other hand, the sensitivity decreased when the number of layers exceeded 5, and the enhancement effect of GO was almost lost at 10 layers. In this study, the gold-deposited glass rod SPR sensor coated with GO showed high sensitivity to caffeine. It was found that this sensor has potential as a new sensor for food analysis.

In the present study conducted soil remediation experiments were conducted for PFAS using liquid activated charcoals. Three types of liquid activated charcoal were injected into lysimeter and then contaminated river water was applied to the soil. Leached water after adsorption by activated charcoal in soil was analyzed using ISO 21675 and revealed several findings. 1) Most PFAS can be stabilized in soil (Andosol) after liquid activated charcoal injection. 2) PFSA seems to be more stabilized than PFCA because of less water solubility. 3) To the best of our knowledge, this is the first report to evaluate rice husk-based activated charcoal (Triporous^TM) for adsorption of PFAS in comparison to coal-based and coconut shell-based activated charcoal, which revealed that both dispersion potency of liquid activated charcoal in soil and affinity to PFAS must have been considered to enable effective remediation. 4) Andosol with higher percentage of organic carbon represented longer residence time of PFAS in soil compared to cray soil which was previously reported. 5) Measurement of fourteen quantified PFAS in leached water using ISO 21675 enabled accurate understanding for kinetics of individual PFAS during soil remediation processes.

This paper describes a simple method for obtaining surface-enhanced Raman scattering (SERS) spectra of trace amounts of ferulic acid. Silver foils whose surfaces were roughened by etching with HNO₃ were used as SERS substrates. Raman peaks originating from trans-ferulic acid were observed when a spectrum of a droplet of a 0.5 mg L⁻¹ trans-ferulic acid solution on the surface-roughened silver foil was measured.

Trans-fat or trans fatty acid (TFA), an invariable component of industrial fat, is considered as one of the major dietary factors associated with increased risk of coronary heart disease. TFA content in foods is not regulated in Japan. The aim of this study was to provide an understanding of the current status of TFA in edible vegetable oils commercially available in Japan. Using high resolution capillary gas chromatography on a very polar cyanosiloxane stationary phase (SP-2560, 100 m × 0.25 mm i.d.), we determined the fatty acid (FA) composition, total TFA levels, and TFA isomers of the 24 brands of edible vegetable oils obtained from the Japanese market. The total TFA contents of these samples were lower than 12.04 g 100 g⁻¹ (av. 1.32 g 100 g⁻¹), accounting for 1.43 % of total fatty acids. Excluding one brand with an exceptionally high TFA content found in a perilla oil sample, the TFA content averaged 0.92 %, which was similar to currently consumed margarines (0.88 %) and fat spreads (0.90 %) made chiefly from vegetable oils. The TFA profiles of the vegetable oils examined were similar to those in margarines and fat spreads, showing that the major TFA components were partially isomerized trans linoleic acid (9c,12c-18 : 2) and trans α-linolenic acid (9c,12c,15c-18 : 3). This suggests that most of the TFA in margarines and fat spreads are derived from the vegetable oils used as raw materials.