Antioxidant compounds, such as polyphenols, are widely contained in food and drink to prevent undesirable oxidation. The FAO/WHO Joint Expert Committee on Food Additives (JECFA) and the Joint FAO/WHO Meeting on Pesticide Residues (JMPR) determine the acceptable daily intake (ADI) based on all available facts at the time of evaluation. JECFA generally sets ADI values based on the lowest relevant no-observed-adverse-effect level (NOAEL) in the most sensitive test species. The ADI values for food additives are commonly derived from NOAEL values in long-term in vivo studies in animals. However, unexpected effects caused by combined reactions may arise, because the ADI is determined for single compounds. There are many ingredients in foods and drinks. In fact, antioxidant compounds are also strong reducing agents. They can act as pro-oxidants under in vitro conditions and in the presence of copper ions. It is necessary that interactions occur in the human body. In this review, we introduced the interaction of antioxidant and pro-oxidant activities using electron spin resonance (ESR) measurements for the increase in reactive oxygen species (ROS) in relation to their structures and interactions with transition metals. The antioxidant activity was assessed with the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay, and the pro-oxidant effect of phenolic compounds on DNA damage was assessed by measuring 8-hydroxy-2'-deoxyguanosine (8-OHdG), which is effectively formed during oxidative damage. In conclusion, ortho-dihydroxyl groups that can chelate with Cu²⁺ induce the greatest pro-oxidant activity. Moreover, the interactions between phenolic compounds and copper induced to H₂O₂ were studied. The obtained results indicated that ROS participated in oxidative stress induced by antioxidant compounds in the presence of Cu²⁺. Those results indicate that combinations of high concentrations of antioxidants and certain metal ions can generate large amounts of ROS in artificial intestinal juice. Further studies will be needed to evaluate the physiological significance of these findings.

The trace elemental analysis of polished rice was performed using X-ray fluorescence (XRF) analysis in order to characterize the geographical origins. Short, medium or long grains of samples collected from 5 origins (Japan, China, Malaysia, Bangladesh, and Myanmar) were powdered and prepared as pressure-molded tablets for analysis. The long-grain types with dry texture required a higher pressure (12 tonf/cm²) and a longer time (10 minutes) for molding. By using an energy-dispersive XRF spectrometer equipped with three-dimensional polarization optics and employing three secondary targets (Ti, Ge, and Zr), 10 elements (P, S, Cl, K, Ca, Mn, Fe, Cu, Zn, Rb) were detected in 15 minutes. The concentrations of P, Mn, Fe, Cu, Zn and Rb were quantified by using calibration curves of each element. Using the elemental concentrations and the stable isotope ratios (δ¹³C, δ¹⁵N, δ¹⁸O), the polished-rice samples were examined by principal-component analysis to classify the geographical origins. The geographical discrimination progressed by combining the elemental compositions and the isotope ratios and, consequently, the Asian rice samples were characterized according to the graphical origins by the complemental parameters.

Ion exchange in crystalline coordination polymers (CPs) has been studied not only as a separation and detection method, but also as a post-synthetic route of new substances. The ion-exchange selectivity, which is one of the most important parameters, sometimes differs from those observed in conventional ion-exchange systems. This is an intriguing phenomena; however, the mechanisms therein have not been elucidated. In the author’s opinion, the structural change of the crystalline framework should be one of the most important factors to affect the ion-exchange selectivity. In this review article, two ion-exchange systems using CPs are presented; one is the ion-exchange of lanthanide ion (Ln³⁺) in a CP comprising of Ce³⁺ and bis(nitrophenyl)phosphate (L1), namely CeL1₃, and the other is alkali-metal ion-exchange in a CP based on La³⁺, alkali metal ion (M⁺), and 1,4-phenylenebis(methylidyne)tetrakis(phosphonic acid) (L2). The former offers an exceptional ion-exchange selectivity, i.e., CeL1₃ replaces Ce³⁺ only by Yb³⁺ and Lu³⁺ with a high loading ratio. Powder X-ray diffraction analysis relvealed that the ion-exchange reaction concommitants with the crystal-structural transition. According to results obtained, an ion-exchange reaction model was proposed. In the latter system, an exceptional selectivity of alkali-metal ion-exchange has already found by another research group, and was explained by the difference in the ionic size between the outgoing and incoming alkali-metal ions. However, the author demonstrates herein that the proposed model was invalid by examining ion-exchange reactions comprehensively and evaluated with the structural change of the framework. It is deduced for the above two cases that the structural strain generated by the coexistence of two kinds of metal ions with different ionic size and that the resulting structural change would be significant for the ion-exchange reactions.

Fluorescence and bioluminescence have been actively applied to various chemical sensors and biosensors, including to cellular/in vivo imaging. On application to the detection of specific targets, it is necessary to develop fluorescent/bioluminescent probes that selectively respond to the target analytes such as molecules, ions or cells by changing their optical properties. The authors have focused on the development of small molecular probes by means of molecular design based on the desired function. In this paper, we describe the approaches to molecular design of fluorescent/bioluminescent probes and their applications, including the introduction of our recent research works. Finally, a future outlook for further functionalization of small molecular probes is provided.

We examined the amount of radioactive cesium eluted into water by the Ministry of the Environment Notification No. 13 Test and the tank leaching test for the municipal solid waste incineration (MSWI) fly ash of 8000 Bq kg⁻¹ or less that can be landfilled. From MSWI fly ash obtained by the two types of dissolution tests, we considered that more than 60 % of the radioactive cesium contained in the incineration fly ash attaches to water-soluble compounds or exists as a water-soluble compound. Treating MSWI fly ash as innocuous is a just issue, and water cleaning treatment was selected as a pretreatment considering, the elution of radioactive cesium from the incineration fly ash buried in the disposal site. From the results of the water washing test by repeated elution treatment and continuous elution treatment, elution was the most practical method for 36 hours continuously. We attempted to separate and concentrate radioactive cesium using three types of solid-phase disks: RAD disk, activated carbon filter paper, and Prussian blue non-woven fabric. RAD disk has a high recovery rate as a method for separating and concentrating radioactive cesium in a cleaning solution obtained by washing fly ash from municipal waste incineration with water.

Since the invention of organic elemental analysis by Pregl CuO has been used as a filler in a combustion tube of conventional elemental analyzers. However, as the tube temperature reaches ca. 1000 °C, the high temperature causes a serious degradation of the tube when many metal containing samples are analyzed. Thus, the new filler, CuO/TiO₂, has been developed to perform the analysis at a lower temperature of 550 °C, inspired by a report that plastic can be decomposed at 500 °C using TiO₂ as a catalyst. Using this filler at 550 °C, CHN elemental analyses were successfully performed for the standard materials of organic elemental analysis, and refractory materials, such as organic silicon compounds, organic fluorine compounds, organic phosphorus compounds and metal chelating materials, which are known to be difficult to analyze. Moreover, this CuO/TiO₂ filler might also be used for a total organic carbon analyzer, where an expensive platinum filler is usually used. Furthermore, graphite was not decomposed almost at all by the present method. Thus, the fractional analysis of organic carbon and elemental carbon can be achieved by performing the analyses at 550 °C for organic carbon and 950 °C for elemental carbon, sequentially. This new technique will be useful in various fields, e.g., in the evaluation of new functional materials containing both organic compounds and elemental carbon, such as carbon nanotubes and carbon nanofibers, as well as, fine-particulate analysis in the environment, etc.

Sixteen commercial vegetable oils and thirteen blended oils were analyzed using liquid chromatograph-mass spectrometer/evaporative light scattering (LC-MS/ELSD) and identified by waveform pattern analysis of obtained chromatograms. Triacylgrycerols (TAGs), which are the main components of vegetable oils, were detected using MS and chromatograms reflecting the TAGs components of each samples were obtained using ELSD at the same time. All samples were identified by waveform pattern analysis of the chromatograms using spectral analysis software. As for blended oils, their ingredients and the compositional ratio could also be presumed. This method was found to be effective for detecting and identifying vegetable oils and blended oils in forensic examination, both quickly and efficiently.

In July 2020, heavy rains caused floods in the Kyushu region, resulting in an accidental spillage of 12 pesticides from a pesticide storehouse upstream of the Chikugo River tributary. In this study, we analyzed the spilled pesticides by a target screening method using GC/MS and LC/MS/MS. Some of the spilled pesticides (iminoctadine,diquat,paraquat) were measured by direct injection using LC/MS/MS. The toxicity of the pesticides to aquatic organisms was assessed by bioassays using algae (Raphidocelis subcapitata), water fleas (Daphnia magna), and fish (Danio rerio) embryos. As a result, no spilled pesticides were detected and no toxic effects were observed on aquatic organisms. The screening method using GC/MS and LC/MS/MS determined chemicals in 1 day, i.e., from sampling to reporting the survey results. The recovery tests of pesticides, using river water in a heavy rain disaster by a target screening method, were at generally acceptable levels (recovery rate: 44-110 %) compared with the target recovery rates (50-150 %). However, the recovery rate of highly hydrophilic pesticides (iminoctadine,diquat,paraquat) was 0.29-0.75 %. Therefore, it is necessary to develop a screening method for hydrophilic substances used in heavy rain disasters.