Vol. 47, No. 7
July, 1998
Toshimitsu Okamoto, Kazuo Takayama, Masaru Ikeda* and Hisomu Nagashima**
*Product Development Laboratories, Sankyo Co., Ltd., 1-2-58, Hiromachi , Shinagawa-ku, Tokyo, 140-0005
**Institute of Science and Technology, Inc., 3-10-2, Kitashinagawa, Shinagawa-ku, Tokyo 140-0001
A graphitized carbon packing sintered from carbonic material at high temperature was examined as a column for the simultaneous determination of alkali metal ions. Combinations of various ion-interaction reagents with nitric acid as an eluent have been investigated in order to optimize the separation of 5 common alkali metal ions (Li+, Na+, K+, Rb+ and Cs+). The calibration curves were linear over the ranges from 0.3 to 8.0 µg/ml for Li+, from 1.0 to 25.0 µg/ml for Na+, from 2.5 to 50.0 µg/ml for K+ and from 3.0 to 75.0 µg/ml for Rb+ and Cs+ with a correlation coefficient (r) of 0.999 or better. The relative standard deviations (RSD) of the peak areas were found to be 0.5~0.9% for 10 replicated measurements. The newly developed method was applied to the determination of Na+ and K+ in pharmaceutical compounds. The analytical results were within ±0.3% of the theoretical value, and were thus in good agreement with the theoretical value for each sample.
Keywords: graphitized carbon; alkali metal ions; pyrocatechol violet; sodium; potassium.
Hiroki Tamura*, Shin-ichi Takasaki** and Ryusaburo Furuichi*
*Research Group of Materials Chemistry, Graduate School of Engineering, Hokkaido University, Kita-13, Nishi-8, Kita-ku, Sapporo-shi, Hokkaido 060-8628
**Kurita Central Laboratories, Kurita Water Industries Ltd., 7-1, Wakamiya, Morinosato, Atsugi-shi, Kanagawa 243-0124
Magnetite, an iron oxide present under reducing conditions, is a component of soils, iron ores, corrosion scales on iron and steels, and others. For a wet analysis of magnetite in samples, magnetite is preliminarily dissolved; the precision and accuracy of the final analytical results are greatly influenced by the dissolution process. A dissolution model would be useful in the design of dissolution processes and control of the optimum dissolution conditions for particular analytical purposes. Here, modeling was made for the kinetics of the dissolution of magnetite in EDTA (H4Y) solutions by assuming the following successive reactions: 1) chelation of the Fe ion sites on Fe3O4 with HnY(4-n)-, and the transfer of Fe chelates to the solution; 2) the reaction of the oxide ion sites left behind on Fe3O4 with protons, and the transfer of the formed water to the solution. The derived rate equation reproduced the time-course of the dissolved Fe concentration and the Fe concentration peaks at pH 2.3. For five EDTA species with different proton numbers (n=0~4), the resulting model parameters (rate constants) were examined in the pH range 1.5~3.3. From the pH dependence of the model parameters, H2Y2- was estimated to be the most likely dissolving EDTA species in solution.
Keywords: magnetite; EDTA; dissolution rate; kinetic model; dissolving EDTA species.
Masahiro Hori*, Kunihiro Uda** and Jian-ping Yang*
*Faculty of Education and Human Science, Yokohama National University, 79-2 Tokiwadai, Hodogaya-ku Yokohama-shi 240-8501
**Komyo-Rikagakukogyo Co., Miyauchi, Nakahara-ku, Kawasaki-shi 211-0051
A simple and rapid method involving a detector tube with a discriminator was developed for low-concentration formaldehyde in indoor air. The detector tube(4 mm in inner diameter) is packed with silica gel(60 to 80 mesh) coated with a mixture of hydroxylamine phosphate and thymol blue. This acts as a pH indicator which changes color from yellow to reddish pink. The discriminator tube connected before the detector tube is packed with hydrogenphosphate-coated silica for ammonia, 3,3'-dimethylnaphtidine-coated celite for nitrogen dioxide and zinc-activated carbons particles for ketones. The sample air is aspirated through them at 300 ml/min with a diaphragm pump, and the measurable concentration ranges are 10 to 120 ppb for 30 min aspiration and 40 to 480 ppb for 10 min aspiration. The detection limit of 1.5 mm in stain length is 5 ppb; the stain length and coefficient of variation at 20 and 100 ppb are 6 mm and 8 %, and 26 mm and 3%, respectively. The reading values on the detector tubes are corrected by means of a temperature-correction factor table, because the stain length is effected by the room temperature, but not the humidity. The ability of the procedure was demonstrated in applying to fields which were different from each other in formaldehyde concentration and co-existing gases.
Keywords: formaldehyde; detector tube with discriminator; indoor air; simple and rapid method.
Kiyoshi Hirakawa, Masashi Nishida, Isao Yoshida and Daido Ishii*
*Division of applied chemistry, Graduate school of Kumamoto institute of technology, Ikeda, Kumamoto-shi, Kumamoto 860-0082
(Received 11 March 1998, Accepted 27 April 1998)The new technology for approaching plug flow in a flow-injection analysis was developed. For that purpose, a flexible fused silica capillary of 0.35 mm outer diameter as the axis of rotation, for example, was inserted into a whole reaction tube of 1.0 mm inner diameter, 100 cm length. The obtained FIA signal was improved to be a symmetrical, such as a Gauss curve. A plug containing the sample and reagents was mixed only in the direction of the radius, and did not mix in the direction of the stream. The diffusion of the injected solute was controlled in the reaction tube. The mixed stream in the reaction tube was changed into plug flow due to the effect of the axis of rotation. This method was also applied to teflon tubing of 0.5 mm inner diameter, 100 cm length used in a normal FIA system. This new technology was also demonstrated for the FIA reaction of iron(III) with acidic KSCN.
Keywords: the axis of rotation; plug flow; diffusion control; FIA.
Hajime Goto, Jin-Ming Lin and Masaaki Yamada*
*Department of Industrial Chemistry, Faculty of Engineering, Tokyo Metropolitan University, Minami-ohsawa, Hachioji-shi, Tokyo 192-0397
(Received 16 March 1998, Accepted 27 April 1998)Very intense chemiluminescence(CL) has been observed upon adding an aqeous solution of luminol and lucigenin on basic metal peroxedes (MgO2, BaO2), which were readily prepared through a treatment of the corresponding metal oxides with hydrogen peroxide. Luminol gives intense CL on both metal peroxides, whereas lucigenin does so only on BaO2. Reactive oxygen species bound firmly to the metal peroxides are thought to be oxidizing agents leading to CL, and were characterized by chemical and ESR methods. From experiments using trappers of the reactive oxygen species, hydroxy(OH) and superoxide(O2-) radicals were suggested to exist stably on the surface of MgO2 and BaO2, respectively. This was confirmed on the basis of the ESR spectra obtained by means of the spin-trapping technique using 5,5-dimethyl-1-pyrroline-N-oxide (DMPO). A reaction scheme is proposed for the formation of the reactive oxygen species.
Keywords: chemiluminescence; basic metal peroxide; luminol; lucigenin; characterization of reactive oxygen species.
Nobuo Nakano, Tetsuya Kawabe*, Masahiro Isaka**and Yasue Nozima***
*Riken Keiki Co., Ltd., 2-7-6, Azusawa, Itabashi-ku, Tokyo 174-8744
**Ebara Research Co., Ltd., 4-2-1, Honfuzisawa, Fuzisawa-shi, Kanagawa, 251-8502
***Ebara Corporation, 11-1, Haneda, Asahi-cho, Ohta-ku, Tokyo 144-8510
An automatic monitor has been developed for measuring ammonia in air using a sensitive tape for ammonia gas. It is based on the color change of the tape by a reaction with ammonia. Tape impregnated with a processing solution containing Rose Bengal (pH indicator), p-toluenesulfonic acid, glycerin and methanol was found to be a highly Sensitive means of detecting ammonia gas, and maintains stable sensitivity for at least one month. When a sample including ammonia was passed through the tape, the ammonia was absorbed on the surface of the tape, and reacted with Rose Bengal to form a stain. The extent of the stain was proportional to the concentration of ammonia at a constant sampling time and flow rate, and could be recorded by measuring the intensity of reflecting light (555 nm). The tape could be used to detect down to 0.5 µg/m3 of ammonia with a sampling time of 10h and a flow rate of 700 ml/min. Reproducibility tests showed that the relative standard deviation of the response (n=10) was 1.3% for 0.5 µg/m3 ammonia. The variation of the ammonia concentration obtained by the monitor showed good agreement with that of ion chromatography. The monitor is a simple and useful method for measuring ammonia gas in clean rooms.
Keywords: monitor of ammonia; ammonia sensitive tape; rose bengal; p-toluensulfonic acid.
Shoji Kurata*
*Criminal Investigation Laboratory, Metropolitan Police Department, 2-1-1, Kasumigaseki, Chiyoda-ku, Tokyo 100-8929
(Received 17 March 1998, Accepted 28 April 1998)In forensic investigations, the identification of pressure-sensitive adhesive poly(vinyl chloride) (PVC) tapes for electrical insulation left at crime scenes can frequently provide useful information in conducting a search for criminals. PVC tapes are mainly composed of PVC backing and a pressure-sensitive adhesive. The main ingredients of adhesive additives comprise mixtures of natural rubber and styrene/butadiene copolymer rubber, plasticizers and various tackifiers. The separation of tackifiers from plasticizers has been very difficult; consequently, most studies on the discrimination of PVC tapes have been carried out by analyzing PVC backing, including various pigments, fillers, plasticizers and stabilizers. In this study, the discrimination of 8 samples of red adhesive PVC tapes was carried out by Fourier-transform infrared spectroscopy and pyrolysis gas chromatography/mass spectrometry on tackifiers, partially separated from adhesives by using florisil column chromatography. The result showed that 8 samples could be classified into 7 groups, and agreed with results obtained by various analyses of PVC backings of those samples. This analytical method was very effective for the qualitative discrimination of PVC tapes.
Keywords: tackifiers; discrimination; PVC tapes; florisil column chromatography; gas chromatography/mass spectrometry.
Susumu Muguruma*, Naoki Oguri, Shigeki Uchino** and Jitsuo Kiji***
*Osaka Laboratory, Japan Analytical Industry Co., Ltd., Unilife 303, 13-8, Higashimikuni 5-chome, Yodogawa-ku, Osaka 532-0002
**Laboratory, Japan Analytical Industry Co., Ltd., 208, Musashi, Mizuho, Nishitama, Tokyo 190-1213
***Department of Materials Science, Tottori University, 4-101, Koyama-minami, Tottori-shi, 680-0945
A ferromagnetic alloy foil (Pyrofoil) has been used in Curie-point pyrolyzer as heating source for pyrolysis. However, it was reported that the yield ratio of the pyrolyzates varied depending on the composition of the metalic substances on the surface of the Pyrofoil. Therefore, this investigation was performed in order to enhance the reproducibility of the pyrolysis by using four testing methods: (1) the use of gold-plated Pyrofoil (G-F), (2) the use of platinum-plated Pyrofoil (Pt-F), (3) double-wrapping method {a sample previously wrapped in an aluminum foil is wrapped over with the Pyrofoil (Al-F)} and (4) the use of non-treated Pyrofoil (N-F). Styrene-methyl methacrylate copolymer {P(S-MMA)} from 0.1 µg to 300 µg and poly(ethylene-terephthalate) (PET) were used as samples. G-F showed the best relative standard deviation (RSD), less than 1.4% when measuring the relative peak ratios; the order of the RSD was G-F<Al-F <N-F<Pt-F. Also, in the case of a PET analysis, use of G-F resulted in the lowest RSD. Thus, it has been clarified that the use of the G-F enhances the reproducibilities in measurements by Curie-point pyrolyzer.
Keywords: Curie-point pyrolyzer; pyrolysis-GC; styrene-methyl methacrylate copolymer and poly(ethylene-terephthalate).
Yusuke Okawa, Hiroyuki Kobayashi and Takashi Ohno*
*Faculty of Engineering, Chiba University, 1-33, Yayoi-cho, Inage-ku, Chiba-shi, 263-8522
(Received 12 March 1988, Accepted 11 April 1998)An FIA system capable of the direct and simultaneous determination of ascorbic acid and glucose in commercial soft drinks is described. The system features a flow-through electrolysis cell (electrochemical filter, ECF) for a coulometric determination based on the quantitative electrolysis of ascorbic acid and a glucose oxidase monolayer electrode for the amperometric determination of glucose. Although ascorbic acid interferes with the glucose biosensor, quantitative electrooxidation in the ECF supresses the error. The glucose biosensor did not exhibit saturation for 0.1 M-order glucose samples. The measured values for nine commercial soft drinks without any pretreatment, such as dilution, showed a good correlation to those determined with conventional methods.
Keywords: flow injection analysis; biosensor; electrochemical filter; glucose; ascorbic acid.
Takayoshi Fujino, Fumiko Yoshikawa and Hayao Noguchi*
*Department of Applied Chemistry, Faculty of Science and Engineering, Kinki University, 3-4-1 Kowakae, Higashiosaka-shi, Osaka 577-8502
(Received 30 March 1998, Accepted 30 April 1998) This study concerned the simultaneous differential determination of mixed inorganic and organic acid by nonaqueous conductometric titration with sodium tetrahydroborate, which was dissolved in N,N-dimethylformamide(DMF). The inflection points were found on conductometric titration curves of a mixed solution of organic and inorganic acid in DMF; they were caused by a difference in the acidity or reactivity. The acid concentration of each of mixed acid was successfully determined simultaneously by the present method. We attempted to identify the ions in the DMF solution and the resulting precipitates during the course of titration by fast atom bombardment mass spectrometry (FAB-MS) and fourier-transform infrared spectroscopy (FT-IR). The determination limit was about 0.01 M by this method.Keywords: nonaqueous conductometric titration; sodium tetrahydroborate; mixed acid; simultaneous differential determination; N,N-dimethylformamide.
Shigeru Terashima, Takashi Okai and Masahiro Taniguchi*
*Geological Survey of Japan, 1-1-3, Higashi, Tsukuba-shi, Ibaraki 305-0046
(Received 13 March 1998, Accepted 21 May 1998)For the determination of boron in geological materials, spectrophotometry with the extraction of methylene blue fluoroborate by dichloroethane is more sensitive than ICP-AES. However, the interference of diverse elements in spectrophotometry is considerably more serious than that in ICP-AES, and the analytical procedures are much more complicated. Although the sample digestion-method with an acid mixture of H2SO4-HF can be safely adopted to common igneous rocks, some sediments and sedimentary rocks are not completely decomposed. A 0.1 g sample was fused with 0.5 g of sodium carbonate, and the melt was dissolved in 6 M HCl; then, boron was directly determined at the 249.678 nm emission line by ICP-AES. A determination limit of 4 µg/g of boron was achieved with a precision of less than 7%. The present method has been successfully applied to the analysis of 28 international geological reference materials.
Keywords: boron in geological reference materials; comparison of ICP-AES and spectrophotometry; sodium carbonate fusion.
Takashi Okai*
*Geological Survey of Japan, 1-1-3, Higashi, Tsukuba-shi, Ibaraki 305-8567
(Received 19 March 1998, Accepted 9 May 1998)A selective chemical leaching technique using 1 M acetic acid or a pH 5 acetate buffer solution (mixture of 1 M acetic acid and ammonium acetate) and an ICP-AES determination were applied to carbonate rock reference samples. In 1 M acetic acid digestion, P2O5 and some components show increased values with an increasing solution/sample ratio. This suggested that much attention should be given to not only the used acid and solution species but also to the solution/sample ratio. The analytical precisions for MgO, Fe2O3, Mn, Sr and Ba were good. However, those for low level components showed a worse precision. The Ba content in pH 5 acetate buffer solution digestion gave higher values than in 1 M acetic acid digestion. This may have been caused by the difference in the barite solubility in those two digestion solutions.
Keywords: selective chemical leaching; carbonate rock; reference samples; ICP-AES.
Naoko Nonose
National Institute of Materials and Chemical Research 1-1, Higashi, Tsukuba, Ibaraki 305-8565
(Awarded by Keio University, dated January 22, 1997)In the present thesis, the mechanisms of spectroscopic interference (spectral overlap caused by interfering ion species) and non-spectroscopic interference (matrix effect) in inductively coupled plasma-mass spectrometry (ICP-MS) were clarified, and analytical methods to reduce such interference described. Interfering ion species were classified into two group: refractory oxide (MO+) and Ar polyatomic ions (ArX+ X=: H,C,O,N). The MO+ resulted from the ionization of undissociated neutral oxides in the ICP. A higher plasma temperature and/or the lower partial pressure of oxygen in the ICP would be required to reduce the formation of oxide ion species. The formation of ArX+ was related to a collision-induced reaction of Ar with X+ occurring at the interface region, and the use of shielded ICP suppressed the collision. While, in ICP-MS coupled with the electrothermal vaporization (ETV) technique, independent matrix effects were observed. One was "signal enhancement caused by hydrogen mixed with argon carrier gas"; the other was "signal enhancement caused by a halogen matrix". Both signal-enhancement effects resulted from the promotion of ionization of analytes through a charge-transfer reaction and/or electron impact. In order to reduce such matrix effects, the separation of trace elements from the matrix constituents would be required.
(Received April 4, 1998)Keywords: inductively coupled plasma mass spectrometry; spectroscopic interference; matrix effect; electrothermal vaporization.
Shin-ichi Ichikawa
Advanced Science Research Center Japan Atomic Energy Research Institute, Tokai-mura, Ibaraki 319-1195
(Awarded by Nagoya University, dated March 12, 1997)In order to search for unknown lanthanide isotopes using on-line isotope separation, the selective mass separation of lanthanides was studied on the basis of monoxide ion formation in a thermal ion-source. For this purpose, an integrated target-ion source and a gas-jet coupled ion source was developed. With these ion sources, off-line and on-line experiments were performed. The off-line experiments were carried out in order to understand the ionization behavior of the elements from Ba to Sm in the ion source, starting with their oxide reagents. The observed MO+/M+ ratio was highest for La and Ce, and decreased with atomic number and temperature. In on-line experiments, La isotopes produced in heavy-ion fusion-evaporation reactions were mass-separated as La16O+, being well separated from the Cs and Ba isobars. Using the gas-jet coupled thermal ion source, Gd and Tb isotopes produced in the proton-induced fission of 238U were observed as m onoxide ions, being well separated from other molecular species, when a small amount of oxygen gas was injected into the gas-jet stream in order to enhance the chemical reaction of M+O -> MO in the ion-source. Using this method, new isotopes of 121La, 125Pr, 127Pr, 165Gd and 166Tb were identified.
(Received April 1, 1998)Keywords: isotope separation on-line; gas-jet coupled ion source; integrated target-ion source; new isotopes, 121La, 125Pr, 127Pr, 165Gd, 166Tb; measured half-life; heavy-ion induced reactions; proton-induced fission of 238U.
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