Identification of acid-stable carmine in imported apple syrup product

An unknown red pigment was purified from an apple syrup product imported from Canada, using a DIAION HP-20 column with methanol as the eluent. By spectroscopic means and chemical synthesis, the isolated pigment was identified as 4-aminocarminic acid, which is the major pigment of acid-stable carmine (a red colorant illegal in Japan). In addition, HPLC and TLC methods were proposed to detect this illegal colorant. While the color of carminic acid changed from yellow to red in the pH range of McIlvaine buffer (3.0-7.0), the color of 4-aminocarminic acid was always red, and also the ultraviolet/visible (UV/Vis) spectra did not change. These characteristics are useful to distinguish 4-aminocarminic acid from carminic acid.     

Determination of ten sulfonyl urea herbicides in unpolished rice by solid-phase extraction cleanup and LC-diode array detection

A liquid chromatographic (LC) method with diode array detection (DAD) was developed for screening of 10 sulfonyl urea herbicide residues in unpolished rice. The investigated herbicides were azimsulfuron, bensulfuron-methyl, chlorimuron-ethyl, chlorsulfuron, ethoxysulfuron, flazasulfuron, imazosulfuron, metsulfuron-methyl, pyrazosulfuron-ethyl and tribenuron-methyl. Acetonitrile-water (2:1) extracts of rice samples were cleaned up with solid-phase extraction cartridges (octadecylsilane-bonded silica (ODS) and graphitized carbon black (GCB)). Three fractions of the GCB eluate were taken for analysis using 3 separate injections in order to avoid interference in LC-DAD analysis and to reduce analyte coelution problems. Recoveries from rice samples fortified with the 10 herbicides at 0.05 and 0.2 microgram/g ranged from 46.6 to 119.6%, and coefficients of variation were 3.1-12.6%. The quantitation limits were 0.01-0.02 microgram/g.     

Structure of acid-stable carmine

Acid-stable carmine has recently been distributed in the U.S. market because of its good acid stability, but it is not permitted in Japan. We analyzed and determined the structure of the major pigment in acid-stable carmine, in order to establish an analytical method for it. Carminic acid was transformed into a different type of pigment, named acid-stable carmine, through amination when heated in ammonia solution. The features of the structure were clarified using a model compound, purpurin, in which the orientation of hydroxyl groups on the A ring of the anthraquinone skeleton is the same as that of carminic acid. By spectroscopic means and the synthesis of acid-stable carmine and purpurin derivatives, the structure of the major pigment in acid-stable carmine was established as 4-aminocarminic acid, a novel compound.     

Chemiluminometric sensor for simultaneous determination of L-glutamate and L-lysine with immobilized oxidases in a flow injection system

A chemiluminometric flow-through sensor for simultaneous determination of L-glutamate (Glu) and L-lysine (Lys) in a single sample has been developed. Immobilized uricase, immobilized peroxidase, support material, coimmobilized glutamate oxidase/peroxidase, support material, and coimmobilized lysine oxidase/peroxidase were packed sequentially in a transparent PTFE tube, and the tube was placed in front of a photomultiplier tube as a flow cell. A three-peak recording was obtained by one injection of the sample solution. The peak height of the first peak was due to the concentrations of urate and other reductants in the sample; the immobilized uricase was used to decompose urate, and the hydrogen peroxide produced was decomposed with a luminol-hydrogen peroxide reaction by immobilized peroxidase. The peak heights of the second and third peaks were free from the interferences from the reductants and were dependent only on the concentrations of Glu and Lys, respectively. Calibration graphs for Glu and Lys were linear at 40-1,000 and 50-1,200 nM, respectively. The sampling rate was 11/h without carryover. The sensor was stable for two weeks. The sensor system was applied to the simultaneous determination of Glu and Lys in serum.     

Atomic force microscopic studies on the structure of bovine femoral cortical bone at the collagen fibril-mineral level

The structure of cortical bone at the collagen-mineral level was investigated by means of atomic force microscopy. Surfaces of the specimens treated with collagenase and ethylenediaminetetraacetic acid (EDTA) were examined. Images of blob-like objects observed in intact specimen became clearly outlined after collagenase treatment; the sizes of the blob decreased, suggesting that each blob had been fragmented by the collagenase treatment. Following EDTA treatment of an intact specimen, an image of thread-like objects appeared; the thread was partly constructed by trains of blobs and the other parts of the threads had a periodic pattern along its longer axis. The period was almost equal to the collagen D-period of the Hodge–Petruska model, indicating that the threads are collagen fibrils and that the blobs are related to the mineral phase in bone. It was concluded that minerals were deposited on and along collagen fibrils. A decorated collagen fibril model for the spatial relationship between mineral and collagen fibril was proposed. According to our model, the mineral inside the collagen fibril is about one forth of the extrafibrillar mineral.     

辐射化学在功能型有机材料研制中的应用

Although radiation-chemical reactions have been applied to many industrial fields, especially to polymer industries, they are mainly aimed at improving mechanical, thermal and surface properties of the materials. Application of radiation chemical reactions to the construction of functional organic materials, such as electronic and optical materials, is relatively few. However, radiation-chemical reactions have the following characteristics that are advantageous for studying and constructing functional organic materials.     

Dielectric relaxation in networks of end-linked dimethylsiloxane oligomers

Networks composed of very short dimethylsiloxane chains were prepared by end-linking dimethylsiloxane oligomers with a tetrafunctional crosslinking agent. Their dielectric properties were studied to elucidate the effects of crosslinks on molecular motion in highly crosslinked networks. The temperature of maximum loss for the primary relaxation process (α process) shifted greatly to high temperature with decrease in the chain length between crosslinks. The activation energy and the width of the absorption curve increased with decrease in chain length. No linear relation existed between the dielectric properties for the α relaxation and the crosslink density. On the other hand, the temperature of maximum loss for the secondary relaxation process (β process) shifted to high temperature with decreasing chain length, but the activation energy was almost independent of the chain length. Characteristics for the α, β and hypersonic relaxations in the networks are discussed in terms of inter- and intramolecular contributions.