BUNSEKI KAGAKU Abstracts

Products of a thermal reaction of chlorpyrifos were analyzed by LC/MS and GC/MS. As a result, it was found that chlorpyrifos undergoes an elimination reaction of phosphate by a thermal reaction. Furthermore, it is indicated that the structural analogue of 2,3,7,8-TCDD arises by a thermal reaction of chlorpyrifos. In addition, the toxicity of the products of the thermal reaction of chlorpyrifos, evaluated by DR-CALUX^®, was higher than that of chlorpyrifos itself.

Sputter etching with cluster ions, formed by several thousands of atoms (moleculars) over, is attracting attention as polymer depth profiling in X-ray photoelectron spectroscopy (XPS). Cluster ion beam etching is a low energy ions irradiation method that can reduce sample damage. We investigated the XPS depth profiling of polymer films by using giant cluster ions, which are charged water droplet giant cluster ions. As a result, it was shown that the charged water droplet cluster ion etching method is very effective for the XPS depth profile analysis of polymers.

We propose a rapid preparation method for the simultaneous analysis of gas-phase polycyclic aromatic hydrocarbons (PAHs) and oxygenated polycyclic aromatic hydrocarbons (OPAHs) by an accelerated solvent extractor (ASE) and solid-phase extraction (SPE). We used polyurethane foam (PUF) for collecting gas-phase PAHs and OPAHs. Recovery of selected PAHs and OPAHs from blank PUF ranged from 80 to 100%, except for low molecular PAHs and OPAHs, such as acenaphthylene, acenaphthene, 1,4-naphthoquinone with a relative standard deviation (R.S.D.) of less than 5%, while their recoveries from the collected PUF ranged from 80 to 120%, except for benzanthrone with a R.S.D. from 10% and 20%. The proposed preparation method in combination with ASE and SPE could be useful for screening gas-phase PAHs and OPAHs, although there is a problem to some extent concerning the collection efficiencies of low molecular PAHs and OPAHs in the gas-phase. The application of the proposed method to samples collected at Shinjuku in June, 2012 revealed that the concentration of PAHs and OPAHs, mainly presented in the gas-phase, was significantly higher than that of PAHs and OPAHs, mainly presented in the particle phase.

The chemiluminescence (CL) reaction of tris(2,2'-bipyridine)ruthenium(III), [Ru(bipy)₃]³⁺, is induced by a coreactant, such as an aliphatic tertiary amine. Therefore, many analytical applications of [Ru(bipy)₃]³⁺ as a CL reagent have been reported. Finding a novel molecule that reacts as a coreactant led us to develop this CL detection technique for a wider range of compounds. We have found that [Ru(bipy)₃]³⁺ reacts with conjugated diene compounds, or five-membered heteroaromatic compounds to emit chemiluminescence in aqueous solutions. In addition, we confirmed the effect of functional groups beside nitrogen of aliphatic amines on the [Ru(bipy)₃]³⁺ CL reaction. Based on these findings, we proposed new chromatographic methods for the determinations of various compounds in environmental, biological, and food samples.

In order to develop implantable devices for the continuous monitoring of interstitial glucose, two kinds of sensors, namely, enzymatic and synthetic receptor-based optical sugar sensors have been fabricated and their response properties evaluated. Enzymatic sensors are based on microscopic pH-sensitive optode beads and glucose oxidase (GOX)-immobilized beads inside hydrophilic membrane capsules with ca. 12 μm thickness. A theoretical model describing the sensor glucose responses was proposed. In this model, the glucose influx and the gluconic acid efflux across the capsule membrane were combined with the enzymatic kinetics inside the capsule. Excellent agreements of the predicted sensor responses with experimentally obtained ones allowed us to confirm that enhanced sensor responses for glucose could be achieved by reducing the gluconic acid efflux across the capsule membrane. The synthetic receptor-based sensors were fabricated by covalently immobilizing phenylboronic acid receptors and boronate specific alizarin dyes on a hydrogel film. Rapid and reversible absorbance responses for fructose were induced by dissociation of the receptor/dye complexes on the film due to competitive complexation between the receptor and the analyte sugar. In addition, to obtain receptors with higher glucose affinity, a series of bis(phenyl boronic acid)-type receptors were designed and synthesized. Among them, it was found that a bis(benzoboroxole)-type receptor possessing a m-xylenediamine linker showed the largest binding constant for glucose.

Herein, we report on the release behaviors of sulfur and chlorine in the gasification process of livestock manure composts, i.e., pig feces compost (PC) and chicken droppings compost (CC) by pyrolysis under reduction atmosphere at low temperatures (<650°C). The pyrolysis of the composts generates gaseous species, tar and soot, containing sulfur and chlorine. The amounts of sulfur and chlorine released from the composts were dependent on increases of the pyrolysis temperatures. More than 80% of sulfur from PC and 39 – 56% from CC were released as gas, tar and soot. In contrast, chlorine released after the pyrolysis of PC and CC was less than 20%. This was considered to be mainly due to the chemical forms of sulfur and chlorine in the composts. Furthermore, the CC char, which contained a large amount of calcium, could be applied as the adsorbent for sulfur and chlorine in the gas, tar, and soot released by the pyrolysis of PC. This would be due to interactions of sulfur and chlorine to calcium in the CC char.

A preparation method of Cd-containing rice grain was developed for X-ray fluorescence (XRF) analysis. Cd-containing rice grain was prepared by putting the base rice grain (white rice; Akita, Japan) into methanol containing an appropriate amount of Cd and then heating and cooling. The resulting rice grain was packed into a polyethylene cup (32 mm internal diameter × 23 mm height) covered with a 6-μm-thick polypropylene film for XRF analysis. In the XRF measurement of Cd Kα, Cd-containing rice grain had a sufficient durability, stability, and repeatability. The calibration curve of Cd constructed with a suite of Cd-containing rice grains showed good linearity (r = 0.996) in the range of 0.50 – 9.8 mg kg⁻¹, whose concentrations of Cd were determined with atomic absorption spectrometry (AAS) using HNO₃-H₂SO₄ decomposition after the XRF measurements. The lower limit of detection of Cd was 0.13 mg kg⁻¹. The target concentrations of Cd in rice grains were in good agreement with the values obtained by AAS after acid decomposition.

We carried out the development of a general-purpose optical interference-type chemical instrument that responds to the refractive index. Toward the determination of a unique solution concentration, high sensitivity and high accuracy, as well as response to a sample solution with a continuously and fast-changing concentration, the phase of interference fringe was adopted as signal. A new sample cell and interferometer consisting of two pieces of glasses placed in a wedge conformation was devised; further, the sample cell was miniaturized. The use of the new sample cell and interferometer consisting of two pieces of glasses placed in a wedge conformation successfully compensated for any signal fluctuations due to a laser instability etc. This measurement system correctly responded to the concentration. The phase change is roughly proportional to the concentration in the region from 0 to 0.3% aqueous solution of ethanol, and detection limit was determined to be 0.022%. This was comparable to that of a commercially available refractive index meter. The system responded quantitatively correctly to continuous and fast changes of the sample concentration to follow almost in time, which showed the possibility of real-time measurements up to a rate of 0.0024% s⁻¹. Measurements of Ni(CH₃COO)₂ were successfully carried out. Although it is necessary to study each case, the applicability for a coloring substance has been suggested.

The expanded π-conjugation of porphyrin macrocycles, which are models of chlorophyll, has been intensively explored for the last two decades. Expanded π-conjugated porphyrin macrocycles exhibit structures, electronic properties, coordination chemistry, and reactivities different from those exhibited by other porphyrin macrocycles. The crystal structure of the light-harvesting antenna complex (LH2) from the Rhodopseudomonas acidophila strain 10050 shows that the active assembly consists of two concentric cylinders of helical protein subunits, which enclose the dimeric pigment molecules. Self-assembling into porphyrin arrays through noncovalent bonds is challenging from the viewpoint of nature's synthetic methodology. In this study, the preparation of a pyrrole-fused porphyrin free base attached with ethoxycarbonyl and aldehyde groups at α-pyrrole positions was achieved. It was easy to introduce a zinc metal ion to the pyrrole-fused porphyrin free base by a conventional methodology. Through previous studies, it has become increasingly apparent that pyrrole-fused porphyrin-zinc complexes are very attractive as self-assembling systems. When we increased the solution concentration of the pyrrole-fused porphyrin-zinc complex from 0.5 mM to 6.0 mM, large changes were detected by ¹H NMR spectroscopy. The significantly upfield chemical shifts observed for the methylene protons of ethoxycarbonyl and part of porphyrin moiety suggest that pyrrole-fused porphyrin-zinc complexes interact with each other through the zinc metal center and carbonyl oxygen. Calculations to fit the theoretical curves to the observed data of methyl and methylene protons were perfomed, and the K value was obtained by the fitting curves.