Analytical Sciences
Online ISSN : 1348-2246
Print ISSN : 0910-6340
ISSN-L : 0910-6340
Volume 23 , Issue 6
Showing 1-25 articles out of 25 articles from the selected issue
Reviews
  • Toshihiro IHARA, Motoko MUKAE
    2007 Volume 23 Issue 6 Pages 625-629
    Published: 2007
    Released: June 12, 2007
    JOURNALS FREE ACCESS
    Much effort has focused on methods for detecting various genetic differences in individuals, including single nucleotide polymorphisms (SNPs). SNP can be characterized as a substitution, insertion, or deletion at a single base position on a DNA strand. There is expected to be on average one SNP for every 1000 bases of the human genome, and some variations located in genes are suspected to alter both the protein structure and the expression level. Therefore, highly sensitive techniques with a simple procedure would be desirable for a high-throughput screening of millions of SNPs widely dispersed throughout the human genome. In this short review, we consider recently reported unique techniques for genotyping in a homogeneous solution, and organize them in terms of the chemical and physical processes accelerated on DNA.
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  • Krystyna PYRZYNSKA
    2007 Volume 23 Issue 6 Pages 631-637
    Published: 2007
    Released: June 12, 2007
    JOURNALS FREE ACCESS
    Solid-phase extraction is an attractive approach in the preparation of many kinds of samples prior to analysis; highly selective sorbents are desirable for this purpose. The objective of this review is to provide updated information about carbon-based sorbents, their interaction modes and potential application for the concentration and separation of metal ions from environmental samples prior to their determination. New selective phases such as fullerenes and carbon nanotubes are described. Selected examples illustrate the potential of these sorbents.
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Original Papers
  • Kenji KATAYAMA, Yoshikuni KIKUTANI, Takehiko KITAMORI
    2007 Volume 23 Issue 6 Pages 639-643
    Published: 2007
    Released: June 12, 2007
    JOURNALS FREE ACCESS
    A new photothermal technique was developed for measuring the flow velocity and making solute concentration measurements in a microchip by using the same optical and instrumental setup. Collinear pump and probe light were irradiated onto a microchip surface on which a grating pattern was fabricated. The pump light induced a temperature change with the grating pattern in a microchannel, and a refractive index change due to a subsequent temperature rise was monitored by a heterodyned diffraction signal of the probe light. The flow velocity and concentration were obtained by monitoring the motion and intensity change of the thermally induced grating, respectively. The dynamic range of the flow velocity measurement was 0.17 - 670 mm/s, which is sufficient for covering most chemical applications of a microchip. The detection limit of the concentration measurement was 2 × 10-6 M for a rhodamine B solution.
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  • Kosuke MUKUMOTO, Sadayoshi WATANABE, Takahiko NOJIMA, Michinori WAKI, ...
    2007 Volume 23 Issue 6 Pages 645-649
    Published: 2007
    Released: June 12, 2007
    JOURNALS FREE ACCESS
    Ferrocenylcarbodiimide (1), which is known to react with a guanine (G) or thymine (T) base of single stranded DNA, was allowed to react with DNA duplex having a single mismatched base pair of G-T, T-T, or T-cytosine (C). Electrophoreograms of the reaction mixture showed that 1 could react with G or T base of the mismatched sites on the DNA duplex. However, 1 also reacted with the G base of the terminal site on the DNA duplex. This showed that 1 can react with an unpaired base or unstable base pair such as a terminal or mismatched base on the DNA duplex. Electrochemical mismatch detection could be achieved after hybridization of the ferrocenylated mismatched DNA duplex with a selected DNA probe-immobilized electrode. These results revealed that 1 has a potentiality of serving as a labeling reagent of mismatched bases on the DNA duplex, which is important in the search for heterozygous single nucleotide polymorphisms (SNPs).
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  • Heyou HAN, Yawen CAI, Jiangong LIANG, Zonghai SHENG
    2007 Volume 23 Issue 6 Pages 651-654
    Published: 2007
    Released: June 12, 2007
    JOURNALS FREE ACCESS
    The interaction of water-soluble CdSe quantum dots (QDs) with gold (Au) nanoparticles was investigated by ultraviolet visible absorption spectroscopy. The results showed that the aggregation of Au nanoparticles was induced by CdSe QDs. The influences of factors such as the size of Au nanoparticles, acidity, buffer concentration and the concentration ratio of the CdSe QDs to Au nanoparticles were each investigated. The comparison of two different particle sizes (16 and 25 nm) of Au nanoparticles that interact with CdSe QDs in the solution showed that the aggregation of small Au nanoparticles (16 nm) is easier than that of big Au nanoparticles (25 nm). At pH 7.0 phosphate buffer solution (0.02 M), the optimal molar ratio of CdSe:Au is about 3100:1 according to calculations.
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  • Hong-Wen GAO, Chun-Lei WANG, Jiang-Yan JIA, Ya-Lei ZHANG
    2007 Volume 23 Issue 6 Pages 655-659
    Published: 2007
    Released: June 12, 2007
    JOURNALS FREE ACCESS
    The complexation between Cu(II) and naphthochrome green (NG) is very sensitive at pH 4.09 with the formation of complex ion [Cu(NG)2(H2O)2]2-. It can thus used for the determination of Cu(II) by the light-absorption ratio variation approach (LARVA) with a good selectivity. Both the ordinary detection procedure and continuous flow analysis (CFA) were carried out, where the latter is fit for continuous and rapid analysis of samples. The limit of detection (LOD) of Cu(II) is only 1 ng/ml, which is favorable for direct monitoring of natural water. About 30 samples could be analyzed per hour by CFA. Cu(II) contents in Yangtze River, West Lake, Taihu Lake of China and seawater near Shanghai were determined with satisfactory results. The CFA-LARVA spectrophotometry was the first to be coupled and it will play an important role in the in-situ analysis of natural water quality.
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  • Koichi SAITO, Atsuko OHMURA, Mikiko TAKEKUMA, Ryoichi SASANO, Yasuhiko ...
    2007 Volume 23 Issue 6 Pages 661-666
    Published: 2007
    Released: June 12, 2007
    JOURNALS FREE ACCESS
    A newly developed large-volume injection (LVI) technique that employs a unique stomach-shaped inlet liner (SSIL) inside of a programmable temperature vaporizer was used for the determination of trace amounts of dioxins in human milk and plasma. The initial temperature and the initial dwelling time of the inlet and the kind of solvent used were found to be critical in determining the analytical sensitivity of dioxins due to the loss of these relatively volatile compounds during solvent vaporization. Human milk and plasma were purified and fractionated by pre-packed multi-layered silica-gel chromatography and activated carbon silica-gel column chromatography. A 20-µL aliquot of the fraction collected from the chromatography with toluene was directly applied to the LVI system in high-resolution gas chromatography/high-resolution mass spectrometry. Excellent correlation (r > 0.97) between the values obtained by the LVI method using the SSIL device and those by the conventional regular-volume splitless injection method was obtained for PCDDs, PCDFs and non-ortho PCBs in human milk and plasma samples.
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  • Li-Bin LIU, Yuki HASHI, Min LIU, Yanlin WEI, Jin-Ming LIN
    2007 Volume 23 Issue 6 Pages 667-671
    Published: 2007
    Released: June 12, 2007
    JOURNALS FREE ACCESS
    Particle-associated polycyclic aromatic hydrocarbons (PAHs) collected in urban air of Beijing were studied using a gas chromatograph mass spectrometer (GC/MS). The average concentration of particle-associated PAHs measured in this work was in the range from 28.53 to 362.15 ng/m3, which suggested a serious pollution level of PAHs in Beijing. The results also showed that the concentration of PAHs in the winter was distinctly higher than that in summer and spring. Benzo(a)pyrene (BaP) and benzo(a)pyrene-equivalent carcinogenic power (BaPE) were adopted to evaluate the PAHs pollution state at the sampling site. Through some diagnostic ratios, it can be concluded that traffic exhaust, especially vehicles with diesel engines, and domestic coal-burning heaters might have a prominent contribution to the PAHs concentration.
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  • Jimmy LAWRENCE, Kay L. ROBINSON, Nathan S. LAWRENCE
    2007 Volume 23 Issue 6 Pages 673-676
    Published: 2007
    Released: June 12, 2007
    JOURNALS FREE ACCESS
    The direct electrochemical oxidation of sodium sulfide has been examined at five different carbon-based electrode substrates (glassy carbon (GC), boron-doped diamond (BDD), edge-plane pyrollytic graphite (EPPG), basal-plane pyrollytic graphite (BPPG) and carbon nanotubes (CNT)). An electrocatalytic response is observed at both the EPPG and CNT electrode compared to that of the other three substrates. The higher capacitative charging currents obtained at the CNT electrode hinder its detection range and, as such, the EPPG electrode has been clearly shown to be the substrate of choice for the direct electrochemical detection of sulfide. The procedure was applied to the recovery of a sulfide spike in river water, with a recovery of 104%.
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  • Hong YAO, Yuanyuan SUN, Xinhua LIN, Yuhai TANG, Ailin LIU, Guangwen LI ...
    2007 Volume 23 Issue 6 Pages 677-682
    Published: 2007
    Released: June 12, 2007
    JOURNALS FREE ACCESS
    An electropolymerized film of eriochrome black T (EBT) has been prepared at a glassy carbon electrode (GCE) by cyclic voltammetry (CV). The poly(EBT) membrane at GCE exhibits an excellent electrocatalytic activity towards the oxidation of epinephrine (EP), ascorbic acid (AA) and uric acid (UA) in acidic solution and reduced the overpotential for the oxidation of EP. The poly(EBT)-coated electrode could separately detect EP, AA and UA in their mixture with the potential differences of 180 and 160 mV for EP-AA and UA-EP, respectively, which are large enough to allow for determination of EP in the presence of AA and UA. Using differential pulse voltammetry, the peak current of EP recorded in pH 3.5 solution was linearly dependent on EP's concentration in the range of 2.5 - 50 µM. Due to its good selectivity and stability, the polymer-coated GCE was successfully applied to the determination of EP in real samples.
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  • Sulekh CHANDRA, Chandan Kumar SINGH, Himanshu AGARWAL, Ram K. AGARWAL
    2007 Volume 23 Issue 6 Pages 683-687
    Published: 2007
    Released: June 12, 2007
    JOURNALS FREE ACCESS
    An attempt has been made to develop a highly selective Cu2+-ion selective electrode based on a poly(vinyl chloride) based sensor using 1,2,5,6,8,11-hexaazacyclododeca-7,12-dione-2,4,8,10-tetraene as ionophore with 61.5% DBP in the presence of 29% PVC, 4.5% ionophore and 5% NaTBP as an anion excluder. The sensor exhibits a near Nernstian potential response of 29.5 ± 0.3 mV per decade over a wide concentration range (2.0 × 10-7 - 1 × 10-1 M) with a detection limit of 8.1 × 10-8 M between pH 3 - 11 with a fast response time of < 5 s. The selectivity coefficient values, as determined by the matched potential method (MPM), indicate excellent selectivity for Cu(II) ions over a large number of ions. The proposed sensor exhibits an adequate shelf life (4 - 5 months) with good reproducibility. The quantification of Cu(II) in electroplating wastewater and various brands of Indian tea was successfully achieved using the proposed sensor.
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  • Xueen JIA, Qingji XIE, Youyu ZHANG, Shouzhuo YAO
    2007 Volume 23 Issue 6 Pages 689-696
    Published: 2007
    Released: June 12, 2007
    JOURNALS FREE ACCESS
    The quartz crystal microbalance method (QCM), in combination with electrochemical impedance spectroscopy (EIS), has been utilized to monitor in situ anti-human IgG adsorption on several Au-based surfaces, bare Au, nanogold/4-aminothiophenol (4AT)/Au, and multi-walled carbon nanotubes (MWCNT)/Au, and succeeding human IgG reactions. Also, the immobilization protocol of anti-human IgG via its glutaraldehyde (GA) cross-linking with self-assembled 4AT on an Au electrode and the subsequent surface immunoreaction were examined. The resonant frequency (f0) and the motional resistance (R1) of the piezoelectric quartz crystal (PQC) as well as electrochemical impedance parameters were measured and discussed. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) of the ferricyanide/ferrocyanide couple were examined before and after electrode modification, the antibody adsorption and antibody-antigen reactions. We found that the amount for antibody adsorption was the greatest on the colloid Au modified surface, and that at MWCNT ranked the second, while specific bioactivity was almost identical on the four kinds of surfaces. Two parameters simultaneously obtained at the colloid Au modified surface, Δf0 and ΔCs (interfacial capacitance), have been used to estimate the association constant of the immunoreaction.
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  • Jun YANG, Xitian PI, Liguo ZHANG, Xiangshao LIU, Jing YANG, Yi CAO, We ...
    2007 Volume 23 Issue 6 Pages 697-703
    Published: 2007
    Released: June 12, 2007
    JOURNALS FREE ACCESS
    A series of symmetrical and asymmetrical microfluidic T-sensors with different inlet angles were fabricated to study the mixing characteristics of a T-type microstructure for generating concentration gradient. Computational fluid dynamics (CFD) simulations showed that the concentration gradient, transition zone and diffusion length were different for various configurations and inlet angles. Quick mix and sharp concentration gradient occurred in the asymmetrical structure with large inlet angle. The observed concentration gradients in the fabricated microchannel were consistent with the theoretical prediction. In this microstructure, stagnant zone and z-direction diffusion also affected the concentration gradient. Based on the simulation results, the microfluidic structure was optimized to generate desired concentration gradient for a cell-based study.
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  • Xiaoguang ZHOU, Chunying ZHENG, Jianshe HUANG, Tianyan YOU
    2007 Volume 23 Issue 6 Pages 705-711
    Published: 2007
    Released: June 12, 2007
    JOURNALS FREE ACCESS
    In this paper, a rapid, high efficient, sensitive and inexpensive approach based on a combination of simple ultrasonic extract and capillary electrophoresis (CE) separation with electrochemical detection (ED), is described to identify herbs by comparing their CE-ED profiles (namely, CE-ED electropherograms). The proposed method takes advantage of ultra-small sample volume, low consumption of organic solvent, simple sample pretreatment and easy cleanup procedure. It was applied to analyze the CE-ED profiles of stems of herb Acanthopanax senticosus (Rupr. Et Maxim.) Harms from different sources and different parts (roots, rhizomes, stems and leaves) of this herb. By comparing peak number, peak height and peak height ratio, we found that the CE-ED profiles showed big differences for the herbs from the different sources and the different parts of this herb. In addition, the distribution of bioactive compounds (isofraxidin, rutin and chlorogenic acid) in the different parts of this herb and their content variations affected by the source were studied with the CE-ED method. Based on their own unique CE-ED profiles, these herbs from the different sources and the different parts of this herb could be easily distinguished. Therefore, the proposed approach could be used as a rapid, high efficient and sensitive method for the identification of herbal medicines.
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  • Qian XIANG, Ying GAO, Yuanhong XU, Erkang WANG
    2007 Volume 23 Issue 6 Pages 713-717
    Published: 2007
    Released: June 12, 2007
    JOURNALS FREE ACCESS
    Capillary electrophoretic separation coupled with end-column amperometric detection for the simultaneous quantification of butylated hydroxyanisole (BHA) and propyl gallate (PG) in food was developed. Important factors affecting separation and detection, such as the running buffer, separation voltage, and detection potential, were investigated in detail. An improved working electrode preparation method was used, where a carbon disk of 33 µm in diameter was sealed in a tip and positioned opposite the outlet of a capillary. The experiments indicated that the preparation method was simple, and the obtained electrode exhibited good flexibility and stability for the determination of phenolic antioxidants. The separation was carried out within 5 min using a 50 cm length capillary, with a solution containing 5 mM phosphate and 5 mM borax of pH 8.84 as a separation buffer, and a separation potential of 20 kV. Amperometric detection was achieved with an applied potential of 0.70 V versus Ag|AgCl| saturated KCl. There was excellent linearity between the peak current and the concentrations of the analytes in the range of 1.8 - 180.2 µg/mL for BHA and 10.6 - 212.2 µg/mL for PG, respectively. Relative standard deviations of 4.92% for BHA and 5.27% for PG were obtained, respectively. The developed method was successfully applied for the determination of antioxidants in several commercial foods.
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  • Fengling CUI, Junli WANG, Yanrui CUI, Jianping LI, Yan LU, Jing FAN, X ...
    2007 Volume 23 Issue 6 Pages 719-725
    Published: 2007
    Released: June 12, 2007
    JOURNALS FREE ACCESS
    The binding of N-(p-ethoxy-phenyl)-N′-(1-naphthyl)thiourea (EPNT) to human serum albumin (HSA) was investigated under simulative physiological conditions by fluorescence spectra in combination with UV absorption spectroscopy and a molecular modeling method. A strong fluorescence quenching reaction of EPNT to HSA was observed, and the quenching mechanism was suggested to be static quenching according to the Stern-Volmer equation. The binding constants (K) at different temperatures as well as thermodynamic parameters, enthalpy change (ΔH) and entropy change (ΔS), were calculated according to relevant fluorescent data and the vant' Hoff equation. This indicated that a hydrophobic interaction was a predominant intermolecular force for stabilizing the complex, which is in agreement with the results of molecule modeling study. The effects of energy transfer and other ions on the binding constant were considered. In addition, synchronous fluorescence technology was successfully applied to the determination of HSA added into the EPNT solution.
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  • Yuji SASAKI, Yumi SUGO, Yoshihiro KITATSUJI, Akira KIRISHIMA, Takaumi ...
    2007 Volume 23 Issue 6 Pages 727-731
    Published: 2007
    Released: June 12, 2007
    JOURNALS FREE ACCESS
    Water-soluble ligands, N,N,N′,N′-tetramethyldiglycolamide (TMDGA), N,N,N′,N′-tetraethyldiglycolamide (TEDGA), N,N,N′,N′-tetrapropyldiglycolamide (TPDGA) and N,N-dipropyldiglycolamic acid (DPDGAc) were prepared and their abilities to complex with and to back-extract the metal cations were investigated. These results indicate that the DGA series and DPDGAc have a stronger complexing ability with Am(III) and Pu(IV) than comparable carboxylic and aminopolycarboxylic acids. Among these ligands, the trend of the strength of their complexing ability is TPDGA ∼ TEDGA > TMDGA ∼ DPDGAc. TPDGA has significant loss to the extraction solvent due to its high hydrophobicity. It is evident from the present work that TEDGA is the best reagent for the reverse-extraction of not only An(III), (IV) but also Ca(II), Sc(III), Y(III), Zr(IV), La(III), Hf(IV), and Bi(III).
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  • Yuji SUZUKI
    2007 Volume 23 Issue 6 Pages 733-738
    Published: 2007
    Released: June 12, 2007
    JOURNALS FREE ACCESS
    The characteristics of color development due to a protein error in the dye-binding method in the presence of a non-ionic detergent has been investigated by the calculations based on the chemical equilibrium of a protein error. The calculation results were compared with those obtained using three pH indicators (Bromophenol Blue, Bromocresol Green and Bromocresol Purple) and three non-ionic detergents in the pH region from 1 to 13. In the experiments, the color development increased with the lower concentrations of the detergents, but decreased at higher concentrations. The pH where the color development reached a maximum value shifted to a higher pH as the detergent was added. These experimental results were reproduced by the calculation when the molar absorptivity of the dye-protein complex was assumed to increase due to adding the detergent. Such agreement between the experimental and the calculated results indicates that the characteristics of the color development in the dye-binding method in the presence of a non-ionic detergent can be analyzed by calculations based on the chemical equilibrium of a protein error.
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