Vol. 4 8 , No. 5
May, 1999
Hiroko Kawamoto* and Osamu Nozaki**
*Department of Medical Technology, Tottori University College of Medical Care Technology, 133-2, Nishimachi, Yonago-shi, Tottori 683-0826
**Department of Clinical Pathology, Kinki University School of Medicine, 377-2, Ohno-Higashi, Osaka-Sayama-shi, Osaka 589-8511
We have developed a novel flow-cell reactor by packing immobilized horseradish peroxidase (HRP) into the flow cell (teflon tube; 0.96 mm i.d; 25 cm long) of a chemiluminescence detector (JASCO, 825-CL), and a highly sensitive determination method for hydrogen peroxide assay by flow injection-chemiluminescence. HRP immobilized gels were made according to Nakane's method using the gels (Fujibo, Chitopeal BCW-3001, 74~210 µm). The activity of the HRP immobilized gels was stable over a period at one year at 4°C in a stock solution (phospate buffer, 0.1 mol/l, pH 6.5). Using the flow cell reactor enabled to us to start chemiluminescent reaction and to detect the light emission simultaneously just in front of the photomultiplier of the chemiluminescence detector by automatical mixing the chemiluminescent reagents. The optimal conditions for detecting hydrogen peroxide (0~10 µmol/l) were that the luminol solution was 0.56 mmol/l, and the flow rate of the HPLC pumps was 0.1 ml/min. The intra-assay reproducibility for H2O2 (4.85 µmol/l) was 2.40% (n=11), and the detection limit was 10 pmol. This method was applied to the assay of glucose, which was converted to H2O2 with glucose oxidase, resulting in intra-assay reproducibilities of 2.79%, 4.85%, 5.70% for standard glucose solutions of 2.7 mmol/l, 5.4 mmol/l and control serum (5.0 mmol/l), respectively.
Keywords: chemiluminescence; flow cell reactor; immobilized horseradish peroxidase; flow injection analysis; hydrogen peroxide.
Keiro Higuchi*, Akiko Inoue, Hiromitsu Tamanouchi**, Takayasu Hattori*** and Shoji Motomizu*
*Department of Chemistry, Faculty of Science, Okayama University, 3-1-1, Tsushimanaka, Okayama 700-8530
**FIA Division, Tokyo Kasei Kogyo Co. Ltd., 6-15-9, Toshima, Kita-ku, Tokyo 114-0003
***Scientific Instrument Division, Asahi Techneion Co. Ltd., 1-3-8, Shinmojikita, Moji-ku, Kitakyusyu-shi, Fukuoka 800-0113
A new portable flow injection system was developed for on-site chemical analysis, which allows the rapid analysis of aqueous samples at sampling sites. The system comprises a newly designed double-plunger micro pump, a six-way sample injector, a reaction coil in a thermostated compartment and a detector. All of these units are connected with 0.5 mm i.d. PTFE tubing. A visible detector is assembled using a maximum wavelength of 525 nm of a light-emitting diode (LED) and 540 nm of an interference filter. The system is of the one-box type, whose dimensions are 160(W)×160(H)×320(D) mm, and is easy to carry to the analysis site; the weight is 8 kg. A thermostated compartment is incorporated into the proposed system in order to be used outdoors, where temperatures are changeable. The system can work with DC 12 V as well as AC 100 V; therefore, a car battery or a portable battery can be used as the power source. The analytical data can be memorized in IC cards or a note-book personal computer connected with a RS232C cable. Furthermore, software on the market can be easily used. By using the proposed system, the on-site determination of nitrogen oxides, such as nitrate and nitrite, could be carried out. Calibration graphs for nitrate and nitrite ions were linear over ranges of 0 to 1.0 ppm and 0 to 100 ppb of N-NO3- and N-NO2- with good precision; the sampling rate was 40~50 samples per hour. The detection limit for N-NO3- and N-NO2- was 0.5 ppb. By using the proposed system, the on-site determination of nitrate and nitrite in river water samples was carried out. The relative standard deviations of ten injections were 0.65% for nitrate and 0.15% for nitrite. Furthermore, nitrate and nitrite in biological samples as a metabolic products of nitric oxide, which have attracted a lot of attension as a messenger of diverse physiological processes, were also determined on-site with high sensitivity. By using a car battery as a power source, the proposed system worked continuously. In addition, it worked for about 5 hours continuously with a portable battery.
Keywords: on-site analysis; portable flow injection analyzer; determination of nitrogen oxide; nitrate and nitrite.
Takatoshi Matsumoto, Kazutoshi Tanabe*1, Kazumitsu Saeki*2, Toshio Amano*3 and Hiroyuki Uesaka*4
*1 National Institute of Materials and Chemical Research, 1-1, Higashi, Tsukuba-shi, Ibaraki 305-8565
*2 Toyama Industrial Technology Center, 150, Ninoue, Takaoka-shi, Toyama 933-0981
*3 Opt Research Inc., 3-1-6, Nihonbashi- Honmachi, Chuo-ku, Tokyo 103-0023
*4 Fujitsu Limited, 2-16-27, Takezono, Tsukuba-shi, Ibaraki 305-0032
At present, there is a strong social need to develop a rapid plastic- wastes discrimination system for recycling plastics. The possibility to discriminate many kinds of plastics rapidly by combining near-infrared spectra measurements and neural network analyses was examined. For that purpose, the near-infrared spectra in the 1.3~2.3 µm wavelength region were measured for about 300 samples of 51 kinds of plastic, and normalized second-derivative spectral data were trained in a three-layered perceptron-type neural network. As a result of a discrimination test using the spectral data averaged for sample groups produced by a cluster analysis, the system showed an overall performance of 77% to discriminate 51 kinds of plastic. The possibility to develop a practical plastics discrimination system using this approach was demonstrated.
Keywords: plastic waste discrimination; neural network; near- infrared spectra.
Akinori Isozaki, Sachiko Kudou*, Hisomu Nagashima** and Tadao Okutani*
*Department of Industrial Chemistry, College of Science and Technology, Nihon University, 1-8-14, Kanda-Surugadai, Chiyoda-ku, Tokyo 101-8308
**Institute of Science and Technology, Inc., 3-10-2, Kitashinagawa, Shinagawa-ku, Tokyo 140-0001
This paper describes a simple and sensitive method for determining selenium in organic selenium compounds by ion chromatography with an oxygen-flask-combustion method. An anion-exchange column packing with porous poly(vinyl alcohol)gel (Shodex IC IF-424, 4.6 mm i.d.×100 mm) is installed in an ion chromatograph equipped with an anion micromenbrane suppressor and a conductometric detector. 1.5mM sodium carbonate and 2.0 mM sodium bicarbonate are the optimal mobile phase for the simultaneous determination of a mixture of 9 anions (F-, Cl-, NO2-, Br-, NO3-, HPO42-, SeO32-, SO42- and SeO42-) under the following conditions: flow rate, 1.0 ml/min; scavenger, 12.5 mM H2SO4; column temperature, 30°C. Several mg of sample are burned in an oxygen flask filled with 20 ml of water as an absorbent, and water is added to make 200 ml. A 50 µl aliquot of a sample solution is injected into the column. The content of selenium by this method is in good agreement with that calculated from the molecular weight within a relative error of 2%. It was found that selenium in an absorbent from the combustion of a sample exists only in the selenite form.
Keywords: determination of selenium in organic compounds by ion chromatography; porous poly(vinyl alcohol)gel; selenate and selenite; oxygen flask combustion.
Yuzo Tamari*
*Konan University, 8-9-1, Okamoto, Higashinada-ku, Kobe-shi, Hyogo 658-0072
(Received 27 November 1998, Accepted 22 February 1999)In a hydride-generation system using 2 mol/l hydrochloric acid as an acid carrier and as the acidity of a measuring solution, tellurium(IV) was detected, whereas tellurium(VI) was not. Instead of 2 mol/l hydrochloric acid, however, a 3.6 mol/l hydrochloric acid solution was recommended to determine the total inorganic tellurium in hair samples. Hair samples (2~4 g) was digested with a mixture of nitric acid and perchloric acid, decomposed by heating on a hot-plate, concentrated up to about 1 ml until white fumes of perchloric acid appeared, and then boiled with 6 ml of 20% hydrochloric acid for 5 minutes to reduce the total tellurium to tellurium(IV). The tellurium(IV) solution was transferred to a centrifugal tube, and the solution pH was adjusted to 9 with aqua ammonia after the addition of 5 mg of iron(III). After centrifuging the tube, an iron(III) precipitation was dissolved with 3.3 ml of concentrated hydrochloric acid, and then diluted to 10 ml with water. The hair tellurium content can be determined by this method without any interferences due to a matrix or minor component of hair, although ppm levels of copper in hair interfere. In this method the recovery of tellurium(IV) added to hair samples was found to be 96.2±2.4%, and no copper was detected in measuring the sample solution. As results, the human-hair tellurium content was found to be in the range of 2~7 ng/g for 3 samples.
Keywords: tellurium(IV) and tellurium(VI); hydride generation-AAS; iron(III) coprecipitation; human hair.
Syuji Okuyama and Toshiyuki Mitsui*
*Criminal Investigation Laboratory, Aichi Prefecture Police H.Q., 2-1-1, Sannomaru, Naka-ku, Nagoya 460-8502
(Received 20 January 1999, Accepted 6 February 1999)In conventional methods, the determination of the mixed ratio for a polyester and cotton mixture in fiber has been performed by the dissolution of fibers or the difference in the specific gravity between each fiber using a large quantity of fiber. In this method, trace samples were used, and measured by infrared spectroscopy. The obtained data were used in calculations for a multivariate analysis. This method was accurate to within 3%. The mixed ratio for a polyester and cotton mixture in fiber could be accurately determined without disappearance of the sample.
Keywords: polyester and cotton mixture; FT-IR; multivariate analysis; principal component analysis.
Yutaka Hayashibe, Hiroyuki Sakurai, Masaaki Katou and Minoru Takeya*
*Mitsubishi Materials Corporation, 1-297, Kitabukuro-cho, Omiya, Saitama 330-8508
(Received 17 November 1998, Accepted 22 February 1999)A fully automated flow-injection system for the spectrophotometric determination of copper and nickel ions in copper electrolyte has been developed. To detect each aqua-complex by utilizing one spectrophotometer, at first, the sum of the absorbance of copper and nickel ions was measured at a reference-path. After mixing a thiourea solution to mask copper ions as the copper-thiourea complex, the absorbance of nickel ion was measured at the sample-path. The concentrations of each element were calculated from the difference of each absorbance and from a dilution factor between the two paths. The reproducibility has been proven to be satisfactory with relative standard deviations of less than 0.8% (RSD, 30 g Cu l-1-15 g Ni l-1 levels, n=5). The determination limits were 1.4 g Cu l-1 and 5.0 g Ni l-1 with 75 ml sample injection. This system permits a throughput of 30 samples per hour. It is suitable for monitoring the concentration of copper and nickel ions in a copper electrolytic process stream.
Keywords: flow-injection; simultaneous determination; copper; nickel; spectrophotometry.
Takashi Masadome* and Yasukazu Asano**
*Department of Chemical Science and Engineering, Ariake National College of Technology, Omuta, Fukuoka 836-8585 **Laboratory of Chemistry, Department of General Education, Ariake National College of Technology, Omuta, Fukuoka 836-8585
(Received 21 December 1998, Accepted 22 January 1999)A potentiometric flow injection determination method for cationic polyelectrolytes utilizing a flow-through-type tetraphenylborate-selective electrode detector is described. The method is based on detecting any concentration decrease of the tetraphenylborate ion by the formation of an ion associate between cationic polyelectrolyte, poly(diallyldimethylammonium chloride) (Cat-floc) and tetraphenylborate ion. The response of the electrode detector, as a peak-shaped signal, was obtained for injected cationic polyelectrolyte samples. A linear relationship was found to exist between the peak height and the logarithmic concentration of Cat-floc with a slope of 17 mV/decade over a concentration range of 5×10-5 to 1×10-3 mol l-1. The detection limit for Cat-floc was 1×10-5 mol l-1. The sampling rate was ca. 12 samples/h.
Keywords: cationic polyelectrolytes; flow injection analysis; plasticized poly(vinyl chloride) membrane; tetraphenylborate-selective electrode; ion associate.
Eiko Nakamura, Naoko Miyauchi, Fumiaki Kobayashi and Hiroshi Namiki*
*Department of Chemistry, Faculty of Education, Yokohama National University, 79-2, Tokiwadai, Hodogaya-ku, Yokohama-shi, Kanagawa, 240-8501
(Received 28 December 1998, Accepted 9 February 1999)In ion chromatography using a high-capacity anion exchange column, such as TSKgel-SAX, and 0.5 M of a NaCl solution as eluent, sulfate was easily eluated from the column. In order to investigate the elution behavior of sulfate, the distribution coefficient (Kd) of mono and divalent anions was determined by the chromatographic method and batch method using TSKgel-SAX(4.3 meq/ml), TSKgel-ODS-80Ts(1.2×10-1 meq/ml) coated with cetyltrimethylammonium ion and TSKgel-IC-anion-PW(3.0×10-2 meq/ml) at various concentrations of NaCl solution. A plot of log Kd vs. log of the NaCl concentration gave a straight line, the slope of which agreed with the charge of the anions. In the TSKgel-SAX column, Kd of sulfate became samller than that of monovalent anions at a NaCl concentration greater than 0.2 M . This result suggested that sulfate was easily eluated from the column in ion chromatography using a high-concentration NaCl solution as the eluent.
Keywords: ion chromatography; elution behavior of sulfate; distribution coefficient of anions.
Sahori Takeda
Environmental Chemistry Section, Department of Energy and the Environment, Osaka National Research Institute, AIST, 1-8-31, Midorigaoka, Ikeda, Osaka 563-8577
(Awarded by Osaka City University dated March 24, 1998)A large number of chemicals have been used and detected in the environmental waters in Japan. To evaluate the pollution exactly, the development of analytical technique for the chemicals in water is important. Micellar electrokinetic chromatography (MEKC) is a new, high-performance analytical method and has a high separation efficiency. The author has carried out fundamental studies on the analysis of environmental pollutants by MEKC. First study is the investigation of the separation principle of MEKC. The distribution coefficients and thermodynamic parameters of the phthalate esters including priority pollutants in micellar solubilization were investigated. The separation mechanism in MEKC with or without added methanol was discussed. The influence of surfactant structures on the migration behavior of aromatic compounds was also investigated. We found three homologous sodium N-acyl sarcosinates and sodium N-lauroyl-N-methyl-β-alaninate were useful for MEKC. The polar moiety of surfactant is significant to change separation selectivity for hydrophilic solutes. The next study is the application of MEKC to the separation of environmental pollutants. Phthalate esters, pesticides for golf links, aniline derivatives and derivatized lower aliphatic aldehydes were successfully separated.
(Received January 13, 1999)Keywords: micellar electrokinetic chromatography; environmental pollutants; separation mechanism; surfactants; buffer composition.
Toshiyasu Matsuoka
Criminal Investigation Laboratory, Aichi Prefectural Police Headquarters, 2-1-1, Sannomaru, Naka-ku, Nagoya 460-8502
(Awarded by Meijo University dated May 13, 1998)A complex of methamphetamine was formed in urine (10 ml) upon the addition of carbon disulfide, copper ion, and ammonia. Methamphetamine (≥ 20 µg) in urine was detected based on the infrared spectrum of the complex extracted with benzene within 20 min. Paraquat in blood (1 ml) or urine (2 ml) was adsorbed on silica gel or a florisil minicolumn. The paraquat (≥ 0.36 µg) was detected by passing a color-producing reagent through a minicolumn. The paraquat in the eluate was determined by colorimetry within 20 min. A simultaneous analysis of paraquat and diquat (≥ 0.5 µg) in a phenolic extract of blood (1 ml) was achieved by second-derivative spectroscopy within 30 min. A gas-phase mini-circulation apparatus was made to recover hydrogen cyanide from blood (1 ml); the hydrogen cyanide (≥ 0.1 µg) was determined by a modified pyridine-pyrazolone method. An overall examination was achieved within 45 min. Methemoglobin and carboxyhemoglobin in blood (3 µl) were determined simultaneously by absorbance at 563 nm within 10 min. These two methods were applied to blood taken from 70 victims of fire and auto exhausts for investigating the causes of death. The bloodstain (20 µl) age could be estimated by using an oxygen electrode and the total hemoglobin within 5 min.
(Received 22 January 1999)Keywords: methamphetamine; paraquat; diquat; hydrogen cyanide; methemoglobin; carboxyhemoglobin; blood; urine; detection; rapid determination; bloodstain age; estimation; oxygen electrode.
Kimihiro Ishimura
Production Technology Laboratories, Kaken Pharmaceutical Co., Ltd., 301, Gensuke, Fujieda-shi, Shizuoka 426-8646
(Awarded by Science University of Tokyo dated September 30, 1998)Anhydrochymotrypsin (AHC), β-cyclodextrin sulfate (β-CD·SUL) and hyaluronic acid (HA) are known to exhibit affinity toward peptides having an aromatic amino acid sequence at their C-termini, heparin-binding proteins and gelatin-binding proteins, respectively. In this study, AHC, β-CD·SUL- and HA-immobilized adsorbents were developed for high-performance affinity chromatography. A column-switching HPLC system consisting of precolumns packed with these novel group-specific adsorbents and a reversed-phase analytical column was also developed for selective on-line enrichment and to separation of bioactive peptides and proteins. Among 14 peptides which contained C-terminal aromatic amino acid sequence and more than 5 amino acid residues, 10 peptides were retained on the AHC-precolumn almost quantitatively. All of the 10 proteins having heparin-binding activity were retained on the β-CD·SUL-precolumn almost quantitatively, while 5 proteins having no heparin-binding activity were not retained. Similarly, 4 proteins having gelatin-binding activity were retained selectively on the HA-immobilized precolumn. Calibration graphs for these peptides and proteins were observed to be linear, and good reproducibility was obtained. In addition to the above characteristics, their precolumns were stable after analyzing more than 200~450 samples during at least a period of 1 year.
(Received February 1, 1999)Keywords: group-specific adsorbent; high-performance affinity chromatography; anhydrochymotrypsin; β-cyclodextrin sulfate; hyaluronic acid; column-switching; precolumn.
Shigeru Amemiya
Department of Chemistry and Biochemistry, The University of Texas at Austin, Austin, Texas 78712
(Awarded by The University of Tokyo, dated March 30, 1998)The potentiometric responses of ion-selective electrodes (ISEs) based on electrically charged receptors and hydrogen-bonding neutral receptors were investigated experimentally and theoretically on the basis of the phase boundary potentials at liquid/liquid interfaces. Neutral derivatives of nucleobases were synthesized and applied to ISEs for nucleotides. Nernstian slopes obtained with these electrodes made it possible to interpret the potentiometric selectivities on the basis of the phase boundary equilibria, giving design strategies for hydrogen-bonding receptors that are suitable for ISE application. Two types of non-Nernstian responses, induced by charged receptors, were explained by taking account of the distribution of two different ions at the phase boundary. Apparently "twice-Nernstianresponses" to dications, whose slopes are two-times larger than Nernstian slopes for dications, were shown to be the only examples of super-Nernstian responses that can be explained by the phase boundary equilibria. The anionic interference for ISEs based on charged receptors and neutral receptors was shown to occur at similar anion concentrations if the charged and neutral receptors form complexes of equal stabilities and stoichiometries. While the use of neutral receptors has been more common than that of charged ones, these results show the high potentiality of charged receptor-based ISEs.
(Received February 2 1999)Keywords: liquid/liquid interface; phase boundary potential; ion-selective electrode; hydrogen bonding; apparently "twice-Nernstianresponse"; anionic interference.
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