BUNSEKI KAGAKU Abstracts

Vol. 54 No. 1

January, 2005

Reviews

New Development in Chemometrics

Takeshi Hasegawa^1,2 and Yukihiro Ozaki³

(Received 16 June 2004, Accepted 28 August 2004)

A recent trend of chemometrics for spectral analysis is summarized. A fundamental concept for the analysis of spectra using chemometrics by considering the spectra as multivariate data is presented, followed by the introduction of a quantitative analysis of spectra, classification of spectra, pretreatment of spectra, and spectral decomposition techniques using the latest examples of chemometric studies.

Keywords : chemometrics; spectral analysis; calibration; vibrational spectroscopy; multivariate analysis.

Accounts

Electrostatic Effects and Involvements of Solvation in Separation of Ions

Tetsuo Okada¹ and Makoto Harada¹

(Received 28 June 2004, Accepted 6 August 2004)

This paper reviews the electrostatic and solvation effects, both of which play decisive roles in separation and recognition of ions. Charged interfaces are often utilized for ionic separation and recognition; ion-exchange chromatography, micellar partition, ion sensors, and solvent extraction are typical examples. Usual stoichiometric rules, which assume two discrete phases and the electroneutrality in both phases, do not apply to such systems where electrostatic energies dominate the entire interaction, because the electrostatic force is exerted beyond a long distance. We have evaluated the results of chromatographic separation of ions with models derived from electrostatic theories, and have revealed various phenomena that were not found by the conventional stoichiometric models. Considerations based on the electrostatic models strongly imply important involvements of ionic solvation in the determination of separation selectivity. X-ray absorption fine structure (XAFS) has thus been applied to elucidate the local solvation structures of ions at separation interfaces. XAFS has very high elemental selectivity, is hardly subject to the interference from matrices, and provides structural data for noncrystalline materials. The local structures of counteranions in anion-exchange resins have been, for example, studied in various solvents, suggesting that tight ion-associations are formed between the ion-exchange groups and halide anions in aprotic solvents, while they are partly dissociated from the ion-exchange sites by complete solvation in water and methanol. In addition, the total reflection of the incident X-ray at the surface of an aqueous solution allows us to study XAFS of ions attracted by surface monolayers. Some results obtained with this novel method are also discussed.

Keywords : electrostatic theory; ionic solvation; separation selectivity; chromatography; X-ray absorption fine structure.

Research Papers

Entrainer Effect of Water on Supercritical Carbon Dioxide Extraction for Dioxins in Soils

Takashi Miyawaki¹, Ayato Kawashima¹ and Katsuhisa Honda¹

(Received 6 May 2004, Accepted 12 August 2004)

The effect of water as an entrainer was studied on supercritical carbon dioxide extraction (SCE-CO₂) of Polychlorinated dibenzo-p-dioxins/polychlorinated dibenzofurans (PCDD/DFs) in paddy soil. Using water as an entrainer elevated the extraction efficiency of PCDD/DFs, and it's optimal extraction condition was as follows: a water flow velocity of 0.04 ml/min (2% versus CO₂ flow velocity); 30~40 MPa, 130~190°C; 50 min dynamic SCE-CO₂. The extraction efficiency of PCDD/DFs by 2% water entrainer was almost the same as those by 10% toluene- and 5% methanol-entrainers, and corresponded to about 80% of those by the conventional method (Soxhlet extraction). These results indicate that SCE-CO₂ with water as an entrainer is rapid and organic-solvent less technique for the extraction of PCDD/DFs in soils.

Keywords : polychlorinated dibenzo-p-dioxins; polychlorinated dibenzofurans; supercritical fluid extraction; soil.

Odor Sensing Based on the Color Changes of pH Indicator/Polyvinylpyrrolidone Films

Satoshi Nishimura¹, Takanori Inoue², Yoshiaki Kurauchi² and Kazuya Ohga²

(Received 21 June 2004, Accepted 31 August 2004)

Changes in the color of pH indicators (Methyl Orange, Methyl Red, Thymol Blue, Phenol Red, Phenolphthalein and Alizarin Yellow) were observed when polyvinylpyrrolidone films containing each of these six pH indecators were exposed to methanol and typical odor components of citrus fruits. Color images of the polymer films obtained with a scanner were separated into red, green and blue components, and then the three components were converted into gray levels, integers from 0 to 255. Differences between the gray levels before and after exposure to the sample gases were characteristic of each of the gases, and showed that Alizarin Yellow/polymer film exposed to linalyl acetate and linalool gave large color changes, as the radar plots of the differences distinctly illustrated. An optical fiber having the Alizarin Yellow/polymer film at the cladding part and a thin gold film on an end surface was used as a sensing element; a decrease in the signal intensity of reflected halogen-lamp light from the fiber was observed at 635 nm when the fiber was exposed to linalyl acetate. A polymer film of 9.00 µm in thickness gave a significant decrease in the intensity; the response reached a steady state in 20 min.

Keywords : odor sensor; optical fiber; pH indicator; polymer film.

Rapid Determination Method of Oxygen Contained in Organic Compounds by Means of Contact Thermal Decomposition

Haruo Honma¹

(Received 13 July 2004, Accepted 11 September 2004)

A procedure for a quick determination of the amount of the oxygen element present by means of contact thermal decomposition is as follows. Approximately 10 ml of carbon black is filled into a molybdenum cylindrical crucible developed by us. The crucible is heated to 1300°C, and a sample contained in a silver capsule is dropped into it for instantaneous thermal decomposition, by which the oxygen element is reduced to carbon monoxide. The principle of the method is that the carbon monoxide is oxidized to carbon dioxide at 650°C, and the amount of the resulting carbon dioxide can be determined using an infrared detector. The method of determination has been established by examining in detail the fundamental aspects listed below: 1) fabrication of prototypes of various instruments and evaluations of their functions, 2) adjustment of the reagent and apparatus used for the determination, 3) determination of a reference value for a blank test value and its behavior, 4) correction for obtaining a linear correlation between the signals detected by an infrared detector and to component concentration, 5) to contact thermal decomposition temperature, 6) a comparison of to effects of contact and no-contact thermal decompositions, 7) an examination of to oxidation condition under low temperature for carbon monoxide and 8) a measurement of to time required for a determination. In this study, the amounts of oxygen contained in several standard samples were determined in order to evaluate the accuracies of the obtained based values on the statistics of the determined values.

Keywords : catalytic pyrolysis; oxygen rapid determination carbon black; molybdenum crucible; molybdenum funnel.

Technical Papers

Development of a Portable Monitor for a Formaldehyde in the Workplace Environment

Yasuhiro Terauchi¹, Tetsuya Kawabe¹, Nobuo Nakano¹, Yoshio Suzuki² and Kouji Suzuki^2,3

(Received 3 June 2004, Accepted 20 August 2004)

A portable formaldehyde gas monitor was developed and applied to measurements of the workplace environment using a sensitive and selective tablet for formaldehyde. It is based on a color change of the tablet by a reaction with formaldehyde. A tablet impregnated with a processing solution containing KD-XA01, phosphate buffer solution in methanol was found to be a highly sensitive and selective for the detection of formaldehyde. When a sample including formaldehyde was exposed to the tablet, the surface color of the tablet changed from white to yellow. The degree of the color change was proportional to the concentration of formaldehyde at a constant sampling time and flow rate, which was recorded by measuring the relative intensity of reflecting light at 400 nm. The tablet was used to detect 0.3 ppm of formaldehyde, which was set by ACGIH, with a sampling time of 3 min and a flow rate of 250 ml/min. Reproducibility tests showed that the relative standard deviation of the response (n=10) was 2.1% for 0.3 ppm of formaldehyde. This monitoring method is simple, specific, and capable of unattended operation, and is recommended for the workplace environment.

Keywords : formaldehyde; portable monitor; tablet for formaldehyde; workplace environment.

Notes

Amperometric Assay of Glutathione in Whole Blood and Serum

Hideaki Kinoshita¹

(Received 20 July 2004, Accepted 20 August 2004)

The anodic steady-state current by a sulfhydryl compound in concentrations about 10 mM at a dialysis membrane covered phthalocyanine-embedded carbon paste electrode (mCoPCPE) completely vanished after the addition of N-ethylmaleimide (NEM) in double concentrations of the sulfhydryl compounds. The concentrations of reduced glutathione (GSH) in whole blood and serum were determined by measuring the current decrease at 150 mV after the addition of NEM in blood solutions of pH 6.8. This method has the advantage of eliminating the procedures for deproteinization. The correlation coefficients between the GSH concentration determined in this method and those by a spectrometric measurement were 0.98 and 0.90 for 10 whole blood and 15 serum samples, respectively

Keywords : glutathione; amperometry; membrane-covered electrode; whole blood; serum.

Highly Accurate Sensing for a Temporal Change in the Freshness of Brown Rice Using a Chemiluminescence Measurement Combined with a Luminol-Peroxidase System

Hiroyuki Noda¹, Tsuneyoshi Goto², Hiroaki Ohya¹ and Hitoshi Kamada¹

(Received 12 July 2004, Accepted 25 August 2004)

Highly accurate sensing for a temporal change in the freshness of brown rice was investigated using a chemiluminescence measurement. The experimental setup was composed of a dark box, a highly sensitive cooled CCD camera (HAMAMATSU, C4880), and a personal computer for data processing. The chemiluminescence intensity was estimated by using a photon counter (HAMAMATSU, C8801). Some pieces of brown rice were placed in the chemiluminescence measurement system. Two kinds of rice, such as new and old ones (stored at one year), were used for chemiluminescence measurements. The addition of 2-methoxyphenol, which is a substrate of peroxidase (POD), led to a decrease in the chemiluminescence intensity of brown rice. Therefore, the luminescence observed may have originated from the POD in brown rice. The chemiluminescence intensity of new rice was fifty-times larger than that of old rice. An increase in the storing period of brown rice at room temperature led to an extreme decrease in the chemiluminescence intensity. Further, the mixture of old and new rice could be distinguished by chemiluminescence imaging. Thus, the chemiluminescence measurement will be a useful technique to evaluate temporal changes in the freshness of brown rice.

Keywords : chemiluminescence; imaging; brown rice; freshness; POD.

The Optimum Recrystallization of Berberine Chloride and Its Quality Check by HPLC

Naomichi Fukuda¹ and Michiko Yonemitsu¹

(Received 6 July 2004, Accepted 10 September 2004)

Berberine and palmatine are isoquinoline alkaloids contained in “oubaku”, Phellodendri Cortex, and their structures are similar. The Rf values of TLC and the retention times (HPLC) of these compounds are close. Their complete separation is difficult; a small quantity of palmatine chloride exists even in a commercial berberine chloride. Some crystals exist in the Student practice, from gel-type crystals (small needles) to big needles according to the volume of water. These phenomena suggest that a possibility exist to purify berberine chloride only by recrystallization. We recrystallized 3 times crude berberine (10 g, gained from the Student practice) from 140 ml of water per 1 g, and separated pure needles (neally 100%, 2.31 g) which were checked with HPLC.

Keywords : berberine chloride; palmatine chloride; purification by recrystallization; quality check by HPLC.

Analytical Reports

Performance of Portable Surface Acoustic Wave Sensor Array Detector for Chemical Agents

Koji Matsushita^1,2, Hiroyuki Sekiguchi^1,2 and Yasuo Seto¹

(Received 14 April 2004, Accepted 28 August 2004)

The detection performance of a portable surface acoustic wave sensor array chemical agent detector (JCAD, BAE Systems) was investigated with nerve gases, blister agents, and blood agents. The vapors of sarin, soman, tabun and lewisite 1 (low level) were recognized as “NERV (nerve agent)” after about 10 sec of sampling, and the detection limits were about 30, 50, 100 and 300 µg/m3, respectively. The vapors of mustard gas and lewisite 1 (high level) were recognized as “BL (blister agent)” after about 10 sec sampling, and the detection limit for mustard gas was about 40 µg/m3. The gases of hydrogen cyanide and cyanogen chloride were recognized as “BLOD (blood agent)” after about 2 min sampling, and the detection limits were about 30 and 1000 µg/m3, respectively. Many solvents, such as methanol, dichloromethane and ammonia, were also recognized as chemical-warfare agents.

Keywords : chemical-warfare agents; on-site detector; detection performance; surface acoustic wave sensor array.

Determination of Rubidium in Infant Formulas by Flame Photometry

Kazuyuki Tsuchiya¹ and Yuzo Tamari¹

(Received 10 May 2004, Accepted 5 September 2004)

The rubidium content of infant formulas was determined by flame photometry using the atomic absorption spectrophotometer (AAS) with air-acetylene flame. In this work, the optimum instrumental conditions for rubidium analysis were determined: the burner height of AAS, the acetylene pressure, the hydrochloric acid concentration as a measuring solution and so on. The effects of coexisting ions expected from matrix components of infant formulas were tested; the results showed no interferences of Na⁺, Ca²⁺, Mg²⁺, PO₄^3- (~250 µg/ml) and K⁺ (~25 µg/ml). In addition, a variation of the sample amount (0.1~1 g) for the analysis did not interfere with the determination of the rubidium content of the sample. Rubidium was determined as follows: A sample (0.3 g) in a beaker (50 ml volume) was decomposed by heating with a nitric-perchloric acid mixture on a hot-plate; the solution was then diluted to 100 ml with water after the addition of 2 ml of 6 mol/l hydrochloric acid. Standard rubidium was recovered to be 100±0.9 (n=20) from an infant formula sample. This method was applied to 24 infant formula samples, resulting in the fact that there was a significant difference in the rubidium content between 10.7±2.9 µg/g (n=14) in follow-up formulas and 5.35±1.71 µg/g (n=10) in young infant formulas (p<0.05).

Keywords : rubidium; rubidium intake; flame photometry; infant formula.

Digests of Doctoral Dissertation

Study on Solvent Effect on Distribution Equilibrium of Palladium(II) in Supercritical Carbon Dioxide Extraction and Solvent Extraction Using 2-Methyl-8-quinolinol

Jin Ougiyanagi

Department of Japan Materials Testing Reactor (JMTR), Oarai Research Establishment, Japan Atomic Energy Research Institute, 3607, Narita-cho, Oarai-machi, Ibaraki 311-1394

(Awarded by Ibaraki University dated March 25, 2003)

The solvent effect on the distribution ratio (D_M) of Pd(II) by extraction with 2-methyl-8-quinolinol (HMQ) was studied using supercritical CO₂ (SF-CO₂) and organic solvents, such as perfluoro-methylcyclohexane, heptane, cyclohexane, carbon tetrachloride and benzene. From the experimental result on the slope of log D_M vs. HMQ concentration plot, the extracted species was determined to be Pd(MQ)₂. A linear relationship was observed in a plot of the distribution constant of HMQ (KD,HMQ) vs. the solubility parameter (d) of the extraction medium based on regular solution theory in both the SF-CO₂ extraction (SFE) and the solvent extraction (SE) systems. The difference in the slope between the SFE and the SE systems is attributable to the extent of the specific interaction of the solute HMQ with the solvent molecules, i.e., CO₂ and the organic solvent molecules. The D_M vs. d plot obtained under a given extraction condition using SF-CO₂ (11~40 MPa) and organic solvents showed clear linearity. The D_M obtained using SF-CO₂ at a pressure range from 8.5 to 11 MPa was independent of the d of SF-CO₂, which coincides with the experimental fact that the solubility of Pd(MQ)₂ in the SF-CO₂ at 8.5 to 11 MPa was practically constant.

(Received July 5, 2004)

Keywords : extraction; supercritical CO₂; organic solvent; palladium(II); 2-methyl-8-quinolinol; distribution constant; solubility parameter.

Studies on Intraparticle Mass Transfer in Silica Gel Using Single-Microparticle Injection and Microabsorption Methods

Tomomi Sekine

Institute for Environmental Management Technology, National Institute of Advanced Industrial Science and Technology, 16-1, Onogawa, Tsukuba-shi, Ibaraki 305-8569

(Awarded by University of Tsukuba dated March 25, 2004)

Mass transfer processes in microparticle/solution systems were kinetically analyzed by a new technique combined with the microcapillary injection/manipulation and microabsorption method of a single microparticle. In situ measurements of both the sorption and desorption processes for the same single particle and the particle size dependencies of the sorption and desorption rates are indispensable for discussing the microscopic mechanisms of the intraparticle mass transfer processes. Quantitative measurements of the intraparticle mass transfer of the dyes in single silica gel microparticles were demonstrated for various pH and ionic strength (I) values using this method. The relationship between these kinetic and isotherm parameters was quantitatively discussed based on a pore diffusion model. The intraparticle mass transfer processes of three dyes in single silica gel microparticles for various pore sizes (d_p) and I values were also investigated. The observed diffusion coefficient (D_o) and the isotherm parameters were highly dependent on d_p (3~30 nm). The relationship between D_o and d_p and the hindrance parameter could be quantitatively analyzed based on the theoretical model of the pore diffusion for the first time. The present approach would be useful to obtain information of diffusion, adsorption/desorption, complexation, and so forth, in nanometer-sized pores of microparticles.

(Received July 26, 2004)

Keywords : microabsorptiometry; single microparticle; mass transfer; sorption/desorption; pore diffusion; surface diffusion; silica gel.

Study on the Preparation and Usage of Standard Solutions for Instrument Calibration

Kazuhiro Shikakume

Chemical Standards Department, Tokyo Laboratory, Chemicals Evaluation and Research Institute, Japan, 1600, Shimo-takano, Sugito-machi, Saitama 345-0043

(Awarded by Yokohama National University dated March 26, 2004)

In this thesis, based on the concept of uncertainty, recently introduced as a replacement for the error, methods for solving several problems in preparing and utilizing standard solutions were studied. The study began by reviewing the methods used to evaluate the uncertainties of the concentration value of standard solutions, while taking into consideration the current state of agreement in the international societies for standard materials and the uncertainties. Secondly, an evaluation of the storage stability, an important factor in the uncertainty of standard solutions, was considered based on newly designed experiments. Accordingly, the effects of the factors and the levels on the storage stability of cyanide ions were evaluated quantitatively by applying signal-to-noise ratios and orthogonal-array experiments. The storage stability under the optimum conditions were revealed. Separately, the article explains that the concentration of the standard solution was reduced due to a degradation of cyanide ions into ammonia and formic acid. Thirdly, for the purpose of evaluating the uncertainty of the quantitative values, the theoretical backgrounds and reasonable calculating method of the quantifications for both cases of the homogeneous precision and the non-homogeneous precision of the values on the ordinate axis are discussed, including an evaluation of the uncertainty of the calibration line parameters. Fourthly, the linearity of the regression line for the calibration in anion determination by ion chromatography with a suppressed conductivity detector was studied both theoretically and experimentally. Depending on the required precision or concentration range, the results indicate that linear regression curve fitting is not always suitable for producing accurate analytical curves.

(Received August 3, 2004)

Keywords : standard solution; uncertainty; storage stability; homogeneous precision; calibration curve; ion chromatography.

Studies of the Organic Chemical Evolution and Stereo Chemistry of Amino Acids in Cosmic and Planetary Extreme Environments

Yoshinori Takano

Institute of Geology and Geoinformation (IGG), National Institute of Advanced Industrial Science and Technology (AIST), AIST Central 7, 1-1-1 Higashi, Tsukuba 305-8567

(Awarded by Yokohama National University dated March 25, 2003)

Stereo chemical verifications of amino acids regarding organic cosmochemical and geochemical approaches were systematically performed. Representative results are as follows. At first, endo- and exogenous abiotic formations of bio-organic compounds were investigated. Among these, we clarified that the primary irradiation products were not free amino acid analogs, but were amino acid precursors having high molecular weight; both proteinous and non-proteinous amino acids were detected after acid-hydrolysis. Secondary, the emergence of an enantiomeric excess of chiral amino acids in meteorite was experimentally verified. The synthesized complex organics containing amino acid precursors from simple gas mixtures were irradiated with right (R-) or left (L-) continuous ultraviolet circularly polarized light (UV-CPL) obtained from synchrotron radiation (SR). Then, R-CPL preferentially photosynthesized D-alanine, and L-CPL yielded more L-alanine. Statistically significant enantiomeric excesses (%D-%L) of +0.44% and -0.65% were obtained by R-CPL and L-CPL, respectively. Thirdly, geological samples in terrestrial extreme environments, such as a semi-permafrost environment, subterranean hydrothermal systems, and deep-sea hydrothermal systems, were analyzed in terms of the concentration of amino acids, the chiral ratio and the enzymatic activities to search for new biospheres. The present findings are therefore strong evidence that those frontiers are previously unknown extreme environment biospheres extending the planetary habitable zone.

(Received August 24, 2004)

Keywords : organic geochemistry; organic cosmochemistry; biosphere; chirality.

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