Analytical Sciences
Online ISSN : 1348-2246
Print ISSN : 0910-6340
ISSN-L : 0910-6340
Volume 20 , Issue 3
Showing 1-32 articles out of 32 articles from the selected issue
Rapid Communications
  • Yuki TANAKA, Kiichi SATO, Masayuki YAMATO, Teruo OKANO, Takehiko KITAM ...
    2004 Volume 20 Issue 3 Pages 411-413
    Published: 2004
    Released: September 02, 2004
    JOURNALS FREE ACCESS
    A microchip-based cell response assay system to an anticancer agent was developed. The hepatoma cell line HepG2 was used to assess the effects of an anticancer agent, doxorubicin. The required cell number was reduced by two orders, and the observation of the time course of cell response became possible. The system clearly showed that treatment with higher doses of the drug or longer exposure times gave more effects to cells. The possibilities of novel drug response studies or toxicity assay system were demonstrated.
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Reviews
  • Shin-ichi ISHIGURO, Yasuhiro UMEBAYASHI, Ryo KANZAKI
    2004 Volume 20 Issue 3 Pages 415-421
    Published: 2004
    Released: September 02, 2004
    JOURNALS FREE ACCESS
    Titration Raman spectroscopy has been developed for studying the solvation structure of metal ions in solution. The method affords us the solvation number, and the value thus obtained in neat solvents is in good agreement with that determined by EXAFS. The method is then applied to solvent mixtures, and the individual solvation number for each solvent is extracted. In a solvent mixture of N,N-dimethylformamide (DMF) and N,N,N′,N′-tetramethylurea (TMU), the metal ion prefers DMF to TMU, which is ascribed to the solvation steric effect. The same applies also for the solvent mixture of N,N-dimethylpropionamide (DMPA) and DMF. However, unlike TMU, DMPA changes its conformation from the planar cis to non-planar staggered upon solvation to the metal ion. The enthalpy for the conformational change of DMPA is positive in the bulk, while it is significantly negative in the coordination sphere of the manganese(II) ion. Here, we briefly describe the procedure of measurements and analyses for the titration Raman spectroscopy, and review the solvation structure of the alkaline earth, first transition metal(II) and lanthanide(III) ions in some solvent mixtures in view of solvation steric effect.
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  • Hitoshi WATARAI, Hideaki MONJUSHIRO, Satoshi TSUKAHARA, Masayori SUWA, ...
    2004 Volume 20 Issue 3 Pages 423-434
    Published: 2004
    Released: September 02, 2004
    JOURNALS FREE ACCESS
    The recent development of new migration methods of micro-particles in liquids using various external fields is reviewed. The combination of a laser scattering force and a photothermal effect produced photothermal-conversion laser-photophoresis. A dielectric field generated in a planer or a capillary quadrupole electrode realized dielectrophoresis. Using a micrometer-scaled magnetic field gradient, the “Magnetophoretic velocimetry” of micro-particles was invented. Furthermore, the Lorentz force generated by combining an electric field and a magnetic field was utilized for electromagnetophoresis. These new methods were overlooked and the advantages in analytical use were discussed.
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Original Papers
  • Yasuhiro IKEZOE, Sadahiro ISHIZAKI, Hiroharu YUI, Masanori FUJINAMI, T ...
    2004 Volume 20 Issue 3 Pages 435-440
    Published: 2004
    Released: September 02, 2004
    JOURNALS FREE ACCESS
    The oscillation of the interfacial tension and electrical potential at a water/nitrobenzene interface was observed with homologous anionic surfactant molecules, sodium-alkyl-sulfates. Concerning small molecules with a short hydrophobic carbon chain, the oscillation period and amplitude decreased with a decrease of the length of the alkyl chain. On the other hand, when surfactant molecules with a long hydrophobic carbon chain were used, no remarkable periodic oscillation occurred after the first oscillation. In all systems, an interfacial flow by Marangoni convection was observed when the oscillation took place. By monitoring the movement of carbon powder scattered on the liquid/liquid interface with a CCD camera, we could observe that the liquid/liquid interface expanded outward from the area on which the surfactant molecules adsorbed when the oscillation occurred. When the small molecule was used, the speed of expansion of the interface (flow speed) was small and shrinkage followed by expansion of the interface repeatedly occurred. However, when the large molecule was used, the flow speed was large and expansion occurred only one time. These results show that hydrodynamic factors and surface activities are important in chemical oscillation systems.
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  • Liang TAN, LianYing LIU, QingJi XIE, YouYu ZHANG, ShouZhuo YAO
    2004 Volume 20 Issue 3 Pages 441-444
    Published: 2004
    Released: September 02, 2004
    JOURNALS FREE ACCESS
    The fluorescence emission spectra and 3D fluorescence spectra of bovine serum albumin (BSA) in cetyltrimethylammonium bromide (CTAB) reversed micelles were affected by the microenvironment. Blue shifts of the fluorescence emission peaks were found when BSA was present in CTAB reversed micelles. The fluorescence intensity changed with the water content. Similar changes in the peak regions of the 3D fluorescence spectra were also observed. CdS nanoparticles prepared in CTAB reversed micelles quenched the fluorescence of BSA significantly. The fluorescence of BSA was more effectively quenched by negative CdS nanoparticles than by positive or neutral CdS ones. The quenching degree increased linearly with increasing the concentration of negative CdS nanoparticles over the range of 5.0 × 10-6 - 3.0 × 10-5 mol L-1. The quenching mechanism is discussed and the quenching constant is 1.32 × 104 L mol-1.
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  • Li ZHANG, Na LI, Fenglin ZHAO, Ke’an LI
    2004 Volume 20 Issue 3 Pages 445-450
    Published: 2004
    Released: September 02, 2004
    JOURNALS FREE ACCESS
    The interaction of Methylene Blue (MB) with chondroitin-4-sulfate (CHS) has been investigated using spectroscopic techniques, including UV-Vis absorption, Rayleigh resonance scattering (RRS), and circular dichroism (CD). The addition of CHS caused a decrease in the absorbance of MB at 664 nm with a new absorption band appearing at 570 nm, enhanced RRS at 314 nm and 560 nm, and also resulted in an intense CD signal at 568 nm. The Scatchard model has been applied to calculating the binding constant and the number of binding sites. The calculated parameters are consistent with the experimental results. The factors affecting the interaction were investigated. Quantitative spectroscopic methods were developed for the first time. They are based on the fact that a decrease in the absorption at 664 nm and an enhancement of the RRS intensity at 314 nm are proportional to the concentration of CHS added in a certain range. Satisfactory results were obtained on the determination of synthetic samples.
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  • Xueguang SHAO, Yadong ZHUANG
    2004 Volume 20 Issue 3 Pages 451-454
    Published: 2004
    Released: September 02, 2004
    JOURNALS FREE ACCESS
    By theoretical analysis, it is found that wavelet transform (WT) with a wavelet function can be regarded as a smoothing and a differentiation process, and that the order of differentiation is determined by the vanishing moment, which is an important property of a wavelet function. Therefore, a method based on the continuous wavelet transform (CWT) for removing the background in the near-infrared (NIR) spectrum is proposed, and it is used in the determination of the chlorogenic acid in plant samples as a preprocessing tool for partial least square (PLS) modeling. It is shown that the benefit of the proposed method lies not only in its performance to improve the quality of PLS model and the prediction precision, but also in its simplicity and practicability. It may become a convenient and efficient tool for preprocessing NIR spectral data sets in multivariate calibration.
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  • Hirotsugu MINAMI, Masako YADA, Tomomi YOSHIDA, Qiangbin ZHANG, Sadanob ...
    2004 Volume 20 Issue 3 Pages 455-459
    Published: 2004
    Released: September 02, 2004
    JOURNALS FREE ACCESS
    A fast and accurate analytical method was established for the simultaneous direct determination of aluminum, calcium and iron in silicon carbide and silicon nitride powders by graphite furnace atomic absorption spectrometry using a slurry sampling technique and a Hitachi Model Z-9000 atomic absorption spectrometer. The slurry samples were prepared by the ultrasonication of silicon carbide or silicon nitride powders with 0.1 M nitric acid. Calibration curves were prepared by using a mixed standard solution containing aluminum, calcium, iron and 0.1 M nitric acid. The analytical results of the proposed method for aluminum, calcium and iron in silicon carbide and silicon nitride reference materials were in good agreement with the reference values. The detection limits for aluminum, calcium and iron were 0.6 µg/g, 0.15 µg/g and 2.5 µg/g, respectively, in solid samples, when 200 mg of powdered samples were suspended in 20 ml of 0.1 M nitric acid and a 10 µl portion of the slurry sample was then measured. The relative standard deviation of the determination of aluminum, calcium and iron was 5 - 33%.
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  • Libo NIE, Jianxin TANG, Huishi GUO, Hong CHEN, Pengfeng XIAO, Nongyue ...
    2004 Volume 20 Issue 3 Pages 461-463
    Published: 2004
    Released: September 02, 2004
    JOURNALS FREE ACCESS
    The gold-label-silver-stain method (GLSS) for DNA hybridization detection has been receiving increased interest as a colorimetric detective method, demonstrating the advantages of non-radioactivity, non-quenching effect of fluorescence and simplicity for analytical equipment. A colorimetric detection based on the GLSS method was applied to DNA arrays in situ synthesized on polypropylene (PP) slices. In this paper a simple plasma treatment was employed to graft amino (-NH2) on the polypropylene slice surfaces, where DNA probes were immobilized via in situ synthesis. Hybridization was accomplished by a sandwich hybridization format. With the amplification of Silver Enhancer Solution, the hybridization signals were recorded with a scanner. A target DNA concentration as low as 100 fM was detected. Complementary and mismatched sequences were clearly distinguished, and the ratio of the background-subtracted gray scale values for a perfect match, single-base mismatch, 2-base mismatch and 3-base mismatch is 22:16:9:4. The sensitivity of the in situ synthesis system was 3 orders of magnitude higher than that of the spotting system, and the signals of the former were about 2-times stronger than that of the latter under the same target DNA concentration.
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  • Ming GUO, Jian-Wei ZOU, Ping-Gui YI, Zhi-Cai SHANG, Gui-Xiang HU, Qing ...
    2004 Volume 20 Issue 3 Pages 465-470
    Published: 2004
    Released: September 02, 2004
    JOURNALS FREE ACCESS
    The binding of gatifloxacin to bovine serum albumin (BSA) in aqueous solution was studied using fluorescence spectroscopy and absorbance spectra. Further, the interactions influenced by Fe3+ and Cu2+ were also explored in this work. Based on Scatchard’s site-binding model and florescence quenching, practical formulas for small molecule ligands to bio-macromolecules have been proposed. The binding parameters were measured according to suggested models, and the binding distance and the transfer efficiency of energy between gatifloxacin and BSA were also obtained in view of the Förster theory of non-radiation energy transfer. The effect of gatifloxacin on the conformation of BSA has also been analyzed using synchronous fluorescence spectroscopy.
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  • Hiroyuki UKEDA, Yukiko ADACHI, Masayoshi SAWAMURA
    2004 Volume 20 Issue 3 Pages 471-474
    Published: 2004
    Released: September 02, 2004
    JOURNALS FREE ACCESS
    A novel flow-injection assay (FIA) system with a double line for catalase activity was constructed in which an oxidase is immobilized and the substrate is continuously pumped to reduce the dissolved oxygen and to generate a given level of hydrogen peroxide. The catalase in a sample decomposed the hydrogen peroxide, and thus the increase in dissolved oxygen dependent on the activity was amperometrically monitored using a Clark-type oxygen electrode. Among the examined several oxidases, uricase was most suitable for the continuous formation of hydrogen peroxide from a consideration of the stability and the conversion efficiency. Under the optimum conditions, a linear calibration curve was obtained in the range from 21 to 210 units/mg and the reproducibility (CV) was better than 2% by 35 successive determinations of 210 units/ml catalase preparation. The sampling frequency was about 15 samples/h. The present FIA system was applicable to monitor the inactivation of catalase by glycation.
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  • Yoshio SUZUKI, Noriyuki TANJI, Chikako IKEDA, Aki HONDA, Kenji OOKUBO, ...
    2004 Volume 20 Issue 3 Pages 475-482
    Published: 2004
    Released: September 02, 2004
    JOURNALS FREE ACCESS
    Novel labeling reagents, called MS probes, which possess a positively charged quaternary amine moiety and can transform a neutral analyte into a charged compound by simply mixing with the analyte and allowing the mixture to stand from several minutes to 30 min at room temperature or while heating to 50°C, were designed and synthesized for the highly sensitive detection of carbonyl, alcohol, carboxylic acid and primary amine samples by electrospray ionization mass spectrometry (ESI-MS). The positively charged products can be detected with high sensitivity in an ESI-MS system, which is the most popular liquid MS instrument. All of the labeled products showed a remarkably large increase in the molecular-ion peak abundance detection sensitivity of over 500-fold at picomolar concentration levels compared to that of unlabeled analytes in an ESI-MS system. These MS probes, used together with liquid MS detection, are widely applicable as a convenient method for the highly sensitive detection of less than picomolar levels of analytes, and therefore greatly enhance the power of ESI-MS analysis.
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  • Nae Yoon LEE, Masumi YAMADA, Minoru SEKI
    2004 Volume 20 Issue 3 Pages 483-487
    Published: 2004
    Released: September 02, 2004
    JOURNALS FREE ACCESS
    A novel pressure-driven sample injection method was developed as an alternative to electrokinetic injection, and electrophoretic separation was carried out on a microfabricated device employing this method. This method enables a defined volume of liquid dispensing, followed by instantaneous injection driven by pneumatic pressure, greatly simplifying the injection procedure. A particular microstructure, called a “metering chamber”, has been designed for the quantitative dispensing of an ultra-low volume of sample liquid; a “hydrophobic passive valve” equipped with an air vent channel is employed for injecting a dispensed sample into the separation channel. The reproducibility of dispensing was 3.3% (n = 15), expressed by the variation of dispensed volumes. The electrophoretic separation of DNA fragments was performed using this injection method, varying the injection volumes from 0.45 to 4.0 nL, and the separation efficiencies were compared. This precise injection method, easily variable in injection volumes, is highly suitable for quantitative as well as qualitative electrophoretic analyses.
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  • Yukitaka NAKANO, Hitoshi NOHTA, Hideyuki YOSHIDA, Kenichiro TODOROKI, ...
    2004 Volume 20 Issue 3 Pages 489-493
    Published: 2004
    Released: September 02, 2004
    JOURNALS FREE ACCESS
    A selective liquid chromatographic method has been developed for the assay of ethambutol in serum samples. The assay involves intramolecular excimer-forming derivatization with 4-(1-pyrene)butanoyl chloride (PBC) and isocratic reversed-phase chromatography with fluorescence detection. After acetonitrile-deproteinization of the serum sample, the derivatization reaction of ethambutol with PBC was completed within 30 min at 50°C. N,N′-Diethylethylenediamine was used as an internal standard. The detection limit of ethambutol was 23 ng/ml serum, corresponding to 180 fmol on column at a signal-to-noise ratio of 3. The present method was selective enough to analyze ethambutol in rabbit serum without any tedious sample clean-up procedure because biogenic monoamines gave no peak in the chromatogram. The method was applicable to drug monitoring in rabbit serum.
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  • Yoshihiko TAGUCHI, Yasuyuki ISHIDA, Hajime OHTANI, Hiroyuki BEKKU, Mas ...
    2004 Volume 20 Issue 3 Pages 495-499
    Published: 2004
    Released: September 02, 2004
    JOURNALS FREE ACCESS
    A polymeric hindered amine light stabilizer (HALS), Tinuvin 622 (MW = 4000), in PP materials formulated with a magnesium hydroxide flame retardant was determined by reactive thermal desorption (RTD) gas chromatography (GC). Two kinds of the HALS components that were formed through the RTD in the presence of tetramethylammonium hydroxide [(CH3)4NOH, TMAH] were clearly observed in the chromatograms of the PP samples, with negligible interference from the other additives and the PP substrate. Here, the coexisting flame retardant was proved to affect significantly the RTD process of the occluded HALS. As a result, the recovery of the HALS components in the RTD-GC chromatograms of the PP samples increased with increase in the content of the flame retardant. This enhancement of the HALS recovery is attributed mainly to the preferential exposure of the HALS on the surface of the ground PP sample through the interaction between the polymeric HALS and the flame retardant in the molten PP during kneading. In spite of such a considerable action of the flame retardant, the observed intensities of the characteristic peaks of HALS by RTD-GC showed a good linear relationship with the HALS content in the PP samples with constant content of the flame retardant (50 phr); this relationship could be used as the calibration line for the determination of the polymeric HALS in the PP materials containing the flame retardant.
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  • B. Ramachandra REDDY, J. Rajesh KUMAR, A. Varada REDDY
    2004 Volume 20 Issue 3 Pages 501-505
    Published: 2004
    Released: September 02, 2004
    JOURNALS FREE ACCESS
    The liquid-liquid extraction of zirconium(IV) from acidic chloride solutions was carried out with Cyanex 272 as an extractant diluted in kerosene. An increase of the acid concentration decreased the percentage extraction of metal, which indicates that the extraction follows ion exchange-type mechanism: MO2+(aq) + 2(HA)2(org) ↔ MO (HA2)2(org) + 2H+(aq), where, M = Zr(IV); HA = Cyanex 272. The extraction of Zr(IV) increases with an increase of the extractant concentration. In a plot of log D vs. log[extractant], M is linear with a slope of ∼2, indicating the association of two moles of extractant with the extracted metal species. On the other hand, the extraction decreases with an increase of the H+ ion concentration. A plot of log D vs. log[H+] gave a straight line with a negative slope of 1.7, indicating the exchange of two moles of hydrogen ions for every mole of Zr(IV). The effect of the Cl- ion concentration at a constant concentration of [H+] did not show any change in the D values. The addition of sodium salts enhanced the percentage extraction of metal, and followed the order of NaSCN > NaNO3 > Na2SO4 > NaCl. The stripping of metal from the loaded organic (L.O) with different acids indicated sulfuric acid to be the best stripping agent. An increase of the temperature during the extraction and stripping stages increases the metal transfer, showing that the process is exothermic. The synergism, regeneration and recycling capacity of Cyanex 272; the extraction behavior of associated elements, such as Hf(IV), Ti(IV), Al(III), Fe(III); and IR spectra of the extracted Zr-Cyanex 272 complex were studied.
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  • Yanling CHEN, Junhua YUAN, Chunxiang TIAN, Xiuzhong WANG
    2004 Volume 20 Issue 3 Pages 507-511
    Published: 2004
    Released: September 02, 2004
    JOURNALS FREE ACCESS
    Poly-Toluidine Blue film was prepared by electrooxidative polymerization at a glassy carbon electrode in a phosphate buffer solution. The resulting chemically modified electrode (CME) exhibited excellent electrocatalysis toward the oxidation of reduced nicotinamide coenzyme (NADH) with over a 450 mV decrease of the overpotential compared with that at a bare glassy carbon electrode. Two electrochemical determinations of NADH, cyclic voltammetry and flow injection analysis, were established based on the electrocatalytical performance of the resulting modified electrode. Under an identical determinate condition, the voltammetric detection for NADH gave a detection limit of 3.3 µmol L-1 with a linear concentration range of 9.1 µmol L-1 to 1.8 mmol L-1. As a detector in a flow-injection system, the CME gave a detection limit of 0.1 µmol L-1 for NADH with a linear concentration range of 1.0 µmol L-1 to 3.2 mmol L-1. Obviously, flow-injection analysis is superior to voltammetric detection in NADH determination for its lower detection limit and wider detectable linear range.
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  • Hiroki OHURA, Toshihiko IMATO, Kiminori KAMEDA, Sumio YAMASAKI
    2004 Volume 20 Issue 3 Pages 513-518
    Published: 2004
    Released: September 02, 2004
    JOURNALS FREE ACCESS
    A method for the potentiometric determination of bromate by circulatory flow injection analysis (CFIA) is described. The procedure involves the use of an Fe(III)-Fe(II) potential buffer solution, which is recycled via a reservoir. The analytical method is based on a linear relationship between the concentration of bromate and a very transient potential change in the electrode potential due to the generation of intermediate bromine during the reaction of bromate with the Fe(III)-Fe(II) potential buffer solution, which also contains NaBr, (NH4)6Mo7O24 and H2SO4. An aliquot (5 µl) of a bromate sample solution was injected into the stream of the potential buffer solution, 100 ml of which was circulated at a flow rate of 1 ml/min; the potential buffer solution stream was then returned to the reservoir after passing through a flow-through redox electrode detector. A potential change due to the reaction of the injected sample with the potential buffer in a reaction coil was measured with the detector in the form of a peak signal. The effects of the bromide, sulfuric acid and Fe(III)-Fe(II) concentrations in the potential buffer, and length of the reaction coil on the peak heights were examined in order to optimize the proposed CFIA method. The analytical sensitivities to bromate were 5.6 mV/µM for 1 × 10-2 M and 30.9 mV/µM for 1 × 10-3 M in the concentration of Fe(III)-Fe(II) in a potential buffer solution containing 0.35 M NaBr, 0.2% (NH4)6Mo7O24 and 1 M H2SO4. The detection limit of bromate obtained by a 1 × 10-3 M Fe(III)-Fe(II) potential buffer solution was 0.02 µM (2.5 ppb). The numbers of repetitive determinations in which the relative sensitivities within 5% were regarded as being tolerated were ca. 4000 and 2000 for the use of only 100 ml of 1 × 10-2 M and 1 × 10-3 M Fe(III)-Fe(II) potential buffer solution, respectively.
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  • Parviz NOROUZI, Mansoor NAMAZIAN, Alireza BADIEI
    2004 Volume 20 Issue 3 Pages 519-526
    Published: 2004
    Released: September 02, 2004
    JOURNALS FREE ACCESS
    A simple and fast stripping voltammetric detection method has been designed for selective and non-selective measurements of heavy metal ions in a flow-injection system. A special computer numerical method is introduced for calculating the analyte signal and noise reduction, where the signal is calculated based on the partial and total charge exchange at electrode surface. For a selective determination, the currents are integrated in the range of the oxidation and reduction of the analyte. For non-selective measurements, the integration range is set for the whole potential scan range (including oxidation and reduction of the Au surface). The time for stripping has been shown to be less than 300 ms. The main advantages of the detection method are as follows: first, removal of oxygen from the measured solution is not required; second, it is sufficiently fast for the determination of heavy metal ions in various chromatographic analysis methods. The limit of detection for tested ions was between 3 × 10-9 and 6 × 10-10 M, and the relative standard deviation at 50 ppb Pb2+ was 4.7% for 10 runs.
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  • Liping LU, Xiangqin LIN
    2004 Volume 20 Issue 3 Pages 527-530
    Published: 2004
    Released: September 02, 2004
    JOURNALS FREE ACCESS
    A novel biochemical sensor was assembled on a glass carbon electrode by a electrodeposition process. Gold nanoparticles were deposited by potential +1.5 V on the glass carbon electrode. CT-DNA was deposited by potential +1.5 V on the gold nanoparticles array electrode. The properties of the modified electrode were characterized by electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). Our results showed that gold nanoparticles increase the DNA membrane capacitance and reduce the membrane resistance. This modified electrode can selectively determine uric acid and norepinephrine in the presence of a larger amount of ascorbic acid. The fabricated electrode showed good sensitivity, reproducibility, and stability.
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  • Mohammad REZA GANJALI, Farhang MIZANI, Mehdi EMAMI, Maryam DARJEZINI, ...
    2004 Volume 20 Issue 3 Pages 531-535
    Published: 2004
    Released: September 02, 2004
    JOURNALS FREE ACCESS
    A cobalt(II) ion-selective membrane sensor has been fabricated from a poly vinyl chloride (PVC) matrix membrane containing a new oxime compound (oxime of 1-(2-oxocyclohexyl)-1,2-cyclohexanediol, OXCCD) as a neutral carrier, sodium tetraphenyl borate (NaTPB) as an anionic excluder and o-nitrophenyloctylether (o-NPOE) as a plasticizing solvent mediator. The membrane sensor exhibits a linear potential response in the concentration range of 1.0 × 10-1 - 1.0 × 10-6 M of Co2+. The electrode displays a Nernstian slope of 29.8 mV decade-1 in the pH range of 3.5 - 8.0. The sensor also exhibits a fast response time of < 25 s. The detection limit of the proposed sensor is 9.0 × 10-7 M (∼40 ng/ml), and it can be used over a period of two months. The selectivity of the sensor with respect to other cations (alkali, alkaline earth, transition and heavy metal ions) is excellent. The practical utility of the sensor has been demonstrated by using it as an indicator electrode in the potentiometric titration of Co2+ with EDTA and for the direct determination of Co(II) in wastewater of the electroplating industry.
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  • Tong-Sheng ZHONG, Guodong LIU
    2004 Volume 20 Issue 3 Pages 537-541
    Published: 2004
    Released: September 02, 2004
    JOURNALS FREE ACCESS
    An amperometric immunosensor was constructed by dispersing graphite, schistosoma-japonicum antigen (SjAg) and silica sol-gel at low temperature. The performance characteristics of the prepared immunosensor were examined in the buffered solution of o-aminophenol (o-AP) used as a substrate. It exhibited excellent physical and electrochemical stability with a renewable external surface. A competitive binding assay was employed to determine schistosoma-japonicum antibody (SjAb) with the aid of horseradish peroxidase labeled SjAb (HRP-SjAb). The experimental parameters for SjAb assay were optimized, including the amount of labeled SjAb in incubation solution, incubation time, temperature and the pH of solution. The use of o-AP substrate and amperometric detection at -250 mV (vs. SCE) results in a determination limit of 0.32 µg/ml and a linear range extending up to 0.18 µg/ml. The results of SjAb assay in serum samples demonstrate the feasibility of using the proposed immunosensor for clinical analysis.
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  • Akiharu HIOKI
    2004 Volume 20 Issue 3 Pages 543-547
    Published: 2004
    Released: September 02, 2004
    JOURNALS FREE ACCESS
    The gravimetric analysis of antimony(III) with oxine (8-quinolinol, Hox) was studied. The amount of antimony left in filtrate and washing solutions was corrected with the results of atomic absorption spectrometry. The weighing form, which had not been conclusive before the present study, was determined to be SbO(ox)(Hox)2. The result (purity of antimony(III) oxide: 99.84 ± 0.05% (m/m)) of the gravimetric analysis was in good agreement with that of coulometric titration with electrogenerated iodine.
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  • Tetsutaro YOSHlNAGA, Makoto TSUCHIDA, Yasushi TOYOSE, Hiroshi HIRATSUK ...
    2004 Volume 20 Issue 3 Pages 549-552
    Published: 2004
    Released: September 02, 2004
    JOURNALS FREE ACCESS
    In an iodometric titration method for iodine (or chlorine) analysis, the percent recovery of iodine (or chlorine) decreases in the low concentration region and at the relatively higher temperature range. We have shown that the percent recovery vs. concentration curve can be expressed by a simple empirical formula. The empirical formula contains parameters that depend on temperature and those parameters were obtained as a function of temperature. The empirical formula can be used as a correction function for experimental iodine (or chlorine) concentrations. By applying the correction function with the parameters to the experimentally obtained concentrations, we can estimate the reliable concentration in the low concentration region. Estimated concentrations were within 10% (as RSD) of the exact values after the correction in the range of 0.4 mg I2 L-1 (≡ ca. 0.1 mg as Cl2 L-1) - 4.4 mg I2 L-1 (≡ ca. 1.2 mg as Cl2 L-1) in the temperature range of 0 to 30°C.
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