BUNSEKI KAGAKU Abstracts

A novel LED-induced fluorescence analysis system using a CD-type microfluidic device was developed to miniaturize the elements of a complete analytical system. The determination of IgA in human saliva by ELISA using the developed system was evaluated. The solutions of the sample, washing reagent, enzyme-labeled anti-IgA, washing reagent and fluorescent substrate in the reservoirs on the CD-type microfluidic device were sequentially introduced into the separation and detection chamber, immobilized with an anti-IgA, by centrifugal force generated by rotation of the CD-type microfluidic device. The determination of IgA was performed by measuring the fluorescence intensity of the enzymatic product using a laboratory-made fluorescence detector with an LED and a CCD. The quantitative values of IgA obtained on the developed system were in excellent agreement with that on conventional ELISA using a 96-well microtiter plate. Since large-size and expensive peripheral equipment, such as a pump, valve, laser and microscope, are unnecessary, this system would be useful for on-site analysis, such as environmental monitoring, food safety testing and point-of-care testing.

An archeo-scientifc study of ancient ceramics aims to contribute to reconstructing the history of non-literate and prehistoric societies. For this purpose, it would be especially significant to uncover the relationship between the production and supply of ceramics in those societies. Sue ware is the most abundantly produced type of ceramics in ancient times, and many kiln sites of Sue ware have been discovered and studied throughout Japan. Hence, we chose this representative type of ancient ceramics as a study subject to develop an X-ray fluorescence method to investigate the provenance of the ceramics. A comparison among the fluorescent spectrums, which were obtained from the excavated Sue wares, revealed that the fluorescent spectrums of K, Ca, Rb and Sr showed region-specific patterns, and thus the kiln sites can be clearly distinguished with the charts of K-Ca and Rb-Sr. The charts of granitic rocks that constitute a basement of Japanese islands showed similar regional specificities, suggesting that the region-specific pattern of the fluorescent spectrum of Sue ware is due to its main component, feldspar, in terms of petrology. A discriminant analysis on the excavated Sue wares from kiln sites and Kofun tumuli revealed that the product from Izumi-Suemura, Osaka, the largest Sue ware production site in the Kofun period, were supplied to all of Japan in a unilateral way, indicating the effectiveness of this method. The method could also be applied to archaeological studies on the ceramics of the ancient and middle ages, such as the issue of production and supply of Haniwa ware that was arranged around Kofun tumulus. Thus, analytical chemistry is very useful for archaeological science of ancient ceramics, suggesting a new way to conduct ceramic archaeology, in which an analytical chemist would participate.

Deposits formed in different parts of automotive engines were characterized by analytical techniques. Also, the methods for clarifying the formation factors of the deposits, such as the formation origins, formation environments and formation routes, were investigated. First, the deposits were classified into three types of ten components based on the difference in their formation origins: four components derived from fuel, three components from engine oil and three components from particulate matter contained in the intake air. Next, the characteristics of these components were examined by four kinds of analytical techniques. The results are as follows. The ten components defined above could be distinguished from one another by four kinds of analytical indexes: chemical structure, elemental composition, thermal gravimetric property and solubility. Of the components, seven of these derived from the fuel and engine oil reflect the environment of the thermal load and the oxygen concentration at the time of deposit formations. Therefore, the formation environment of a target deposit could be estimated from the deposit composition determined by the analytical indexes. Furthermore, the deposit formation routes, which vary with different gas flows and oil flows of the engine inside, could be estimated in two ways. If the formation routes were limited in advance, it would be effective to examine the composition differences between a target deposit and the deposits of each expected route. If the formation routes were uncertain, it would be effective to examine the difference in the component distribution contained in a target deposit.

The tritium migration behaviors in lithium titanate (Li₂TiO₃) and lithium-enriched lithium titanate (Li_2＋xTiO₃) were investigated by Evolved Gas Analysis (EGA) using proportional counters and liquid scintillation counters. Li_2＋xTiO₃ was considered to be a mixture of Li₂TiO₃ and Li₄TiO₄ structures. Tritium release related to the Li₄TiO₄ structure appeared in the tritium EGA spectra for Li_2＋xTiO₃. It was clarified from kinetic analysis for the isothermal tritium release rate that the tritium release behaviors for Li_2＋xTiO₃ were found to be controlled by the diffusion process in the Li₂TiO₃ structure. On the other hand, the defective structure and/or structure boundary induced by the Li₄TiO₄ structure would rerain tritium diffusivity in Li_2＋xTiO₃.

In this study, an experiment to investigate the thermal behavior of perfluorooctanoic acid (PFOA) adsorbed on granular activated carbon (GAC) was carried out. PFOA of a known amount adsorbed by GAC was heated by an electric furnace with a gas mixture of oxygen and nitrogen being used for the carrier gas. The samples were analyzed by using LC/MS/MS, an ion chromatograph, and an atmospheric pressure helium- radiofrequency barrier plasma discharge-atomic emission spectrometry (He-rfBD-AES) to analyze the behavior of PFOA from form changes and the mass balance of F. A heating experiment of PFOA was also carried for a comparison. When PFOA was heated, it evaporated at 150°C and 300°C. The generation of fluoride and decomposition compounds along with the combustion was confirmed at 500°C. When PFOA adsorbed by GAC was heated, PFOA and the homologues did not evaporate at 150°C. Additionally, the generation of fluoride was confirmed at 150°C and 300°C. It was indicated that GAC inhibits the evaporation of PFOA, and facilitates the combustion reaction of PFOA compared with when PFOA was heated without using GAC.

This paper discusses the validity of the mixture-fraction model with the assumption of chemical equilibrium, which is widely used to simulate a diffusion flame. Two equilibrium models were tested: (1) a single-step equilibrium model that considers only the fuel, oxygen, nitrogen, carbon dioxide, and water vapor; (2) a multi-step equilibrium model that considers 53 intermediate species. These equilibrium models were compared with the results of a detailed-chemistry model that considers the rates of 325 elementary reactions. The detailed-chemistry model was applied to one-dimensional counterflow diffusion flames. Temperature and mass fractions computed by the detailed-chemistry model were generally between the values given by the two equilibrium models. Depending on the condition and the range of mixture fraction, either a single-step equilibrium model or a multi-step equilibrium model better approximated the detailed-chemistry model. When the flame temperature was increased by using pure oxygen as the oxidizer, the multi-step equilibrium model tended to be more accurate than the single-step equilibrium model.

The application of electrochemical sensors to biochemical analysis is attractive, because the measurement is fast, easy, and continuous in a turbid cell suspension. In addition, the apparatus used is inexpensive. In this paper, we report on how electrochemical sensors, such as oxygen electrode and ion sensors, are useful to analyze the photoinactivation of bacteria induced by dyes. Furthermore, we coupled a K^＋ sensor with spectrometry. This methodology enabled us to rapidly screen the sizes of pores formed in a liposomal membrane. We also describe a simple method for constructing ion sensors in a laboratory.

When fluid molecules are confined in a narrow gap between two smooth surfaces, their dynamic properties are completely different from those in the bulk. The molecular motions are highly restricted, and the system shows “solid-like” responses when sheared slowly. In this paper, we describe friction measurements of molecularly confined films of a variety of fluids (from simple liquids to polymer melts) using a surface forces apparatus (SFA). Because the optical technique of SFA (fringes of equal chromatic order) allows us to perform accurate measurements of the true contact area and fluid film thickness during sliding, we can evaluate the dynamic structure of confined fluids. The following topics are described in this paper: i) molecular solidification mechanism of fluids due to confinement; ii) structural change of confined fluids in “stop-start” measurements; and iii) layering transition of a confined polymer melt during sliding.

The characterization of Islamic yellow opaque glazed pottery excavated from the Raya site, Egypt, was carried out at an archeological site in Sinai, Egypt, using a portable X-ray fluorescence spectrometer and a portable X-ray powder diffractometer that we developed. The X-ray analyses revealed a cubic yellow pigment, Pb₂Sn_2−XSb_XO_6＋X/2, in the yellow opaque glaze. This pigment formed a continuous solid solution with the replacement of tin by antimony. The calculated lattice constants from the powder diffraction data showed an increase in the cubic lattice constant as the Sn/Sb ratio increased. The X-ray powder diffraction pattern of the yellow pigment showed a strong preferred orientation parallel to the (111) plane. This phenomenon seemed to be caused by crystal growth of the yellow pigment, and may be related to weathering of the glaze. SEM-EDS analysis was carried out in our laboratory to study the weathering mechanism of the yellow opaque glazed pottery, using samples excavated at the Fustat site, Egypt, which are housed in a collection at Waseda University, Japan. The samples were analyzed to reveal the relationship between the chemical composition and the weathering of the glaze. It was found that if the base glaze is an alkali, the yellow glaze metamorphosed into a powdery state by weathering. In contrast, if the base glaze was lead, the yellow glaze became exfoliated from the clay body by weathering.

SEM-EDX analyses of insulator samples are usually believed to be difficult because of charge-up effect, and thus carbon or gold evaporation was performed prior to the SEM observation. However, such an electric conductive thin film will emit characteristic X-rays, interfering the EDX analysis. In the present study, we report that using an anti-static spray is an easier and more effective way than using an ionic liquid. Possibility of metal corrosion by the anti-static spray should be noted.

The measurement error due to protein in measuring the pH by a test strip was analyzed based on the chemical equilibrium of a protein error. The measurement error depends on the ratio of the molar absorptivities of the dissociated molecule of a pH indicator and the pH indicator-protein complex, the concentrations of a pH indicator and protein and pH; it becomes a positive error or a negative error. However, the pH at which no measurement error occurs also exists, and depends on the ratio of the molar absorptivities of the dissociated molecule of a pH indicator and the pH indicator-protein complex. This pH is higher than the pK_D value of a pH indicator in the case that this ratio is large, and is lower than it in case that this ratio is small. The measurement error increases as the protein concentration increases and the dye concentration decreases. In addition, as the pH rises, a positive error decreases and a negative error increases.

The intermolecular π-π charge-transfer (CT) complex formation ability of electron acceptors, such as p-chloranil, tetracyanoethylene, 7,7,8,8-tetracyanoquinodimethane, 2,3-dichloro-5,6-dicyano-1,4-benzoquinone, and 1,2,4,5-tetracyanobenzene, has been evaluated as retention factors of HPLC using a phenyl-silica column as a stationary phase with mobile phase consisting of heptane and benzene. It was found that there is a good linear correlation between the retention factors of the acceptors and the formation constants (K_CT) for the CT complexes with pyrene. On the other hand, half-wave reduction potentials (E_1/2) as experimental LUMO energies of acceptors are well correlated with the intermolecular CT band energies based on Mulliken’ CT theory, but unfavorably explain the K_CT values. Therefore, the retention factors obtained by the HPLC system are considered to be a direct indicator value of the intermolecular π-π type CT ability of electron acceptors. The proposed procedure could be useful as a simple method to know the intermolecular CT ability of acceptors instead of the electrochemical measurement of the E_1/2 values.