Abstracts

Abstract

STUDIES ON MIMIC PEROXIDASE BEHAVIORS OF MOLYBDENUM(VI)–SODIUM DODECYL SULPHATE COMPLEX FOR THE DETERMINATION OF HYDROGEN PEROXIDE AND GLUCOSE by Li‐Hua Chen, Chemical School, Nankai University, Tianjin, 300071, China and Chemical Department, Jishou University, Jishou City, Hunan, 416000, China; Liu‐Zhan Liu and Han‐Xi Shen, Chemical School, Nankai University, Tianjin, 300071, China

ABSTRACT: Some transition metals–sodium dodecyl sulphate (M–SDS) complexes are used to mimic the active group of peroxidase. The catalytic characteristics of these mimic‐enzymes in the oxidation reaction of fluorescence substrate, pyronine B (PB), with hydrogen peroxide have been studied. Though the catalytic activities of M–SDS complexes are much lower than horseradish peroxidase (HRP), they can catalyze the oxidation reaction of PB with hydrogen peroxide leading to fluorescence quenching of PB. Mo(VI)–SDS complex exhibited the highest catalytic activity among same type mimic enzymes. Under optimum conditions, linear relationship between fluorescence quenching F ₀/F and concentration of H₂O₂ is in the range of 0.0–8.6 × 10⁻⁷ M. By coupling this mimic catalytic reaction with the glucose oxidase, glucose can be detected. Linear relationship between F ₀/F and concentration of glucose is in the range of 0.0–1.4 × 10⁻⁷ M. The method has been applied to the determination of glucose in human serum and the results are in good agreement with the method of phenol‐4‐aminoantipyrine.

Analytical Letters, 37(4), 561–573, 2004

Abstract

ELECTROCHEMICAL BEHAVIOR AND ANALYTICAL APPLICATIONS OF SELF‐ASSEMBLED MONOLAYERS ON GOLD ELECTRODE WITH A COBALTOUS PORPHYRIN by Yongsheng Wang, Jingwan Kang, Haixia Wu, Zhonghua Xue, and Xiaoquan Lu, Department of Chemistry, Northwest Normal University, Lanzhou 730070, P.R. China

ABSTRACT: A porphyrin 5‐(4‐hydroxyethoxyphenyl)‐10,15,20‐trisphenylporphyrin (HEPP) was synthesized. The voltammetric behavior of gold electrodes modified with neutral free‐base and positively charged cobaltous center porphyrin films through exposed hydroxyl and pre‐assembled carboxyl terminal via coupled reaction were investigated using Fe(CN)₆ ^3−/4−, ascorbic acid (AA), and dopamine (DA) as probe species. The voltammetric sensing of AA at the physiological level in the presence of DA can be achieved on functionalized self‐assembled monolayer (SAM) of short chain cobaltous porphyrin. The selectivity of response can be improved by introducing structural defects and positively charged center (Co²⁺) in monolayer modified electrode. The results showed that the current of AA anodic peak and its concentration had a linear relationship in a wide range of concentration from 4 × 10⁻⁷ to 2 × 10⁻² mol L⁻¹. The detection limit obtained by differential pulse voltammetry was 6.9 × 10⁻⁸ mol L⁻¹.

Analytical Letters, 37(4), 575–590, 2004

Abstract

APPLICATION OF THE DISORGANIZED MONOLAYER GOLD ELECTRODE TO COPPER DETERMINATION IN WHITE WINE by Grégoire Herzog and Damien W. M. Arrigan, NMRC, University College, Lee Maltings, Prospect Row, Cork, Ireland

ABSTRACT: Underpotential deposition stripping voltammetry (UPD‐SV) at disorganized monolayer‐modified gold electrodes was employed for the determination of copper in white wine. Spontaneous adsorption of 2‐mercaptoethane sulfonate (MES, HS–CH₂–CH₂–SO₃ ⁻) onto gold electrodes results in formation of a porous, disorganized monolayer. This protects the electrode surface from organic matter present in the wine which otherwise adsorbs onto the electrode surface and passivates it. Detection of copper was performed by UPD‐SV in acidified wine matrix. The approach was validated by the analysis of two spiked wine samples, yielding recoveries of 96% and 95% with relative standard deviations of 7% and 16%, respectively. These results demonstrate the ability of disorganized monolayer‐modified gold electrodes for detection of copper in white wine.

Analytical Letters, 37(4), 591–602, 2004

Abstract

SILVER COMPOSITE ELECTRODE FOR VOLTAMMETRIC DETERMINATION OF HALOGENIDES by S. Šebková and T. Navrátil, J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Dolejškova 3, 182 23 Prague 8, Czech Republic; M. Kopanica, Department of Analytical Chemistry, Faculty of Science, UNESCO Trace Element Satellite Center at Charles University in Prague, Albertov 2030, 128 43 Prague, Czech Republic

ABSTRACT: The application of the silver composite electrode prepared from silver, graphite powder and methacrylate resin for the voltammetric determination of halogenide ions was studied. Cathodic direct (DC) current as well as differential pulse (DP) stripping voltammetry (DPV) enable direct determination of chloride, bromide, as well as iodide ions. The achieved limits of detection for all determined ions are sufficient for practical analytical purposes (tap water, natural water, etc.) and results reported in this paper are fully comparable with results achieved using other electrodes. The possibilities of sample analysis without elimination of the presence of surface‐active substances or of dissolved oxygen were studied. The silver composite electrode represents a suitable sensor for analytical purposes and seems to be promising for replacement of mercury electrodes in many cases.

Analytical Letters, 37(4), 603–628, 2004

Abstract

DETERMINATION OF THEOPHYLLINE IN DRUGS AND TEA ON NANOSIZED COBALT PHTHALOCYANINE PARTICLES MODIFIED CARBON PASTE ELECTRODE by Gong‐Jun Yang, Kun Wang, Jing‐Juan Xu, and Hong‐Yuan Chen, The State Key Laboratory of Coordination Chemistry, Institute of Analytical Science, Department of Chemistry, Nanjing University, Nanjing 210093, P.R. China

ABSTRACT: Metallophthalocyanine (MPc) and its derivatives are well known as electrocatalysts to catalyze oxidation or reduction of some species, such as cysteine, nitric oxide. Their nanosized particles may display the potential optics, electronic, catalytic, and structural properties. In this paper, carbon paste electrodes (CPE) modified with nanosized cobalt phthalocyanine (Nano‐CoPc) particles (Nano‐CoPc‐CPE) are fabricated. The electrocatalytic oxidation of theophylline (THP) on the Nano‐CoPc‐CPE is investigated by means of differential pulse voltammetry. The Nano‐CoPc particles perform better electrocatalytic activity to THP, the response current enhanced about 3.4 times compared to bulk CoPc‐modified CPE (B‐CoPC‐CPE). On optimal conditions, there is a good linear relationship between anodic peak current and THP concentration in the range of 4.0 × 10⁻⁷–1.0 × 10⁻⁴ mol L⁻¹ with the detection limit of 1.4 × 10⁻⁷ mol L⁻¹ (S/N = 3). The current responses of successive 40 measurements at the identical surface and at the renewed ones of Nano‐CoPc‐CPE are examined with relative standard deviation of 2.1% and 3.5%, respectively. It indicates that the electrode shows a good stability and reproducibility. It can be used to determine THP in tea and drug without separation from the matrix. The possible electrocatalytic mechanism is investigated by means of electrochemical method and UV/VIS spectroscopy.

Analytical Letters, 37(4), 629–643, 2004

Abstract

IN VITRO SELECTION OF DNA APTAMERS ON CHIPS USING A METHOD FOR GENERATING POINT MUTATIONS by Ryoichi Asai, Shin I. Nishimura, Takuyo Aita, and Katsutoshi Takahashi, Computational Biology Research Center (CBRC), National Institute of Advanced Industrial Science and Technology (AIST), Tokyo, Japan

ABSTRACT: We successfully developed a novel selection method for the acquisition of DNA aptamers that selectively recognize resorufin using on‐chip selection in combination with method for point mutations. This method proved efficient for selection for DNA aptamers of single‐stranded oligo‐DNAs. A genetic algorithm was applied to produce oligonucleotides for the combinatorial library. A fluorescent molecule, resorufin, was applied for the ligand selection as a target. The binding affinity of the library was analyzed by the DNA chip. This selection method of DNA ligands includes on‐chip selection and point‐mutated sequence, which the highest affinity was selected. The fluorescence intensity of the library on the DNA chip increased after three repetitions of the selection round. The average of response for the affinity test increased with each generation.

Analytical Letters, 37(4), 645–656, 2004

Abstract

PREPARATIVE NATIVE CONTINUOUS POLYACRYLAMIDE GEL ELECTROPHORESIS (PNC‐PAGE): AN EFFICIENT METHOD FOR ISOLATING CADMIUM COFACTORS IN BIOLOGICAL SYSTEMS by Bernd Kastenholz, Research Centre Juelich, Institute for Phytosphere Research (ICG‐III), 52425 Juelich, Germany

ABSTRACT: A new electrophoretic method [preparative native continuous polyacrylamide gel electrophoresis (PNC‐PAGE)] was developed to isolate cadmium cofactor‐containing proteins in biological systems. For this purpose Arabidopsis cytosol was subjected to gel permeation chromatography (GPC) and high molecular mass cadmium proteins (MW ≈ 200 kDa) in a GPC fraction of this plant were isolated by PNC‐PAGE. Furthermore plant cytosol was directly separated by this method. The cadmium concentrations in all GPC and PAGE fractions were determined by GF‐AAS using matrix modifier. As electrophoresis buffer of the PAGE method a Tris–HCl buffer (20 mM Tris, 1 mM NaN₃, pH 10.00) was used. The gel (degree of polymerization of the polyacrylamide: 4%; gel length: 4 cm) was polymerized for 69 hr. By these procedures it was revealed that the high molecular mass cadmium proteins of Arabidopsis can be detected in quantitative amounts by using PNC‐PAGE. It could be shown that the chemical structure of the cadmium proteins did not change under these PAGE conditions. PNC‐PAGE is supposed to be an efficient method for isolating other metal cofactors such as Zn, Cu, Ni, Pd, Co, Fe, Mn, Pt, Cr, and Mo and might be suitable for subsequent structural determinations of metalloproteins present in PAGE fractions.

Analytical Letters, 37(4), 657–665, 2004

Abstract

ANALYSIS OF CERIVASTATIN IN HUMAN PLASMA AND IDENTIFICATION OF ITS LACTONE METABOLITE BY CAPILLARY ELECTROPHORESIS by Hassan Y. Aboul‐Enein, Pharmaceutical Analysis Laboratory, Biological and Medical Research Department (MBC‐03), King Faisal Specialist Hospital and Research Center, P.O. Box 3354, Riyadh, 11211, Saudi Arabia and Imran Ali, National Institute of Hydrology, Roorkee, 247 667, India

ABSTRACT: A simple, fast, inexpensive, and reproducible method was developed for the analysis of cerivastatin in human plasma and identification of its metabolite by capillary electrophoresis (CE). The back ground electrolyte (BGE) used was phosphate buffer (50 mM, pH 3.5) with 15 kV as the applied voltage. The detection was achieved by using UV mode at 254 nm and the detection limit of cerivastatin and its metabolite was approximately 5 µg mL⁻¹. The separation and resolution factors were 1.07 and 4.01, respectively. The recovery of cerivastatin from plasma using SPE was 80%.

Analytical Letters, 37(4), 667–678, 2004

Abstract

SPECTRAL RESOLUTION OF A BINARY MIXTURE CONTAINING VALSARTAN AND HYDROCHLOROTHIAZIDE IN TABLETS BY RATIO SPECTRA DERIVATIVE AND INVERSE LEAST SQUARE TECHNIQUES by Erdal Dinç, Bengi Uslu, and Sibel A. Özkan, Department of Analytical Chemistry, Faculty of Pharmacy, Ankara University, Ankara 06100, Turkey

ABSTRACT: Two new spectral approach (graphical and chemometric techniques) were applied for resolution of a binary mixture of valsartan (VST) and hydrochlorothiazide (HCT) in tablets without a separation procedure. In the ratio derivative spectrophotometry, analytical derivative amplitudes were measured at 231.5 and 260.5 nm for VST and at 270.6 nm for HCT in the first derivative of the ratio spectra. The calibration graphs follow Beer's law in the ranges of 8–24 µg mL⁻¹ for VST and 2–10 µg mL⁻¹ for HCT. The prepared calibrations for the first technique were tested for the synthetic binary mixtures of both drugs. Mean recoveries and relative standard deviations were found as 100.4% and 1.76% for VST, 102.5% and 2.41% for HCT, respectively. In the inverse least square technique, absorbances matrix were produced by measurements in the spectral range from 225 to 280 nm of the interval of Δλ = 5 nm at 12 wavelengths in zero order spectra of the various binary mixtures. The prepared calibration set for the absorbance and concentration values were used to predict the concentration of VST and HCT in their binary mixtures and tablets. The “Maple V” software was used for the numerical calculations. For this technique, mean recoveries and relative standard deviations were found as 101.2% and 1.58% for VST and 96.2% and 2.35% for HCT. Both techniques were successfully applied for the determination of these two drugs in tablets.

Analytical Letters, 37(4), 679–693, 2004

Abstract

COBAT(III) HEXAMETHYLENEDTHIOCARBAMATE AS A NEW COLLECTOR FOR FLOTATION PRECONCENTRATION OF IRON, NICKEL, LEAD, AND ZINC PRIOR TO ETAAS by Umit Ay, Department of Chemistry, Science Faculty, Kocaeli University, Izmit, Republic of Turkey; Katarina Cundeva, Trajěe Stafilov, and Gorica Pavlovska, Institute of Chemistry, Faculty of Natural Science, Sts. Cyril and Methodius University, Skopje, Republic of Macedonia; Göksel Akçin, Department of Chemistry, Faculty of Science and Art, Yildiz Technical University, Istanbul, Republic of Turkey; Vesna Paneva Zajkova, Faculty of Mining and Geology, Sts. Cyril and Methodius University, Štip, Republic of Macedonia

ABSTRACT: A fast method for separation of iron, nickel, lead, and zinc from water matrices prior to their atomic absorption spectrometry (AAS) is described. The separation and preconcentration of metals was performed by precipitate colloid flotation with cobalt(III) hexamethylenedithiocarbamate, Co(HMDTC)₃, as a new collector. The optimal conditions for flotation of each analyte by Co(HMDTC)₃ were determined. After flotation separation analytes were analyzed by flame atomic absorption spectrometry (FAAS) or electrothermal atomic absorption spectrometry (ETAAS) depending of their concentrations in the water sample. The results of AAS analyses are compared with those obtained by inductively coupled plasma‐atomic emission spectrometry. The limit of detection of analytes was determined 0.838 µg/L for iron and 1.105 µg/L for zinc using FAAS and 0.129 µg/L for lead and 0.113 µg/L for nickel by ETAAS.

Analytical Letters, 37(4), 695–710, 2004

Abstract

SPECTROPHOTOMETRIC METHOD FOR THE DIRECT DETERMINATION OF ANIONIC SURFACTANT SODIUM DODECYL BENZENESULPHONATE (SDBS) USING A HYDROPHOBIC NEAR‐INFRARED (NIR) CATIONIC CYANINE DYE WITHOUT SOLVENT EXTRACTION by Yuqin Wu, Jinlong Chen, Shujuan Zhuo, Lun Wang, Yongxin Li, and Changqing Zhu, College of Chemistry and Materials Science, Anhui Normal University, Wuhu, 241000, China; Hong Zheng, The Key Laboratory of Analytical Science of MOE, Department of Chemistry, Xiamen University, Xiamen 361005, China

ABSTRACT: A new hydrophobic near‐infrared (NIR) cationic cyanine dye was synthesized and evaluated as a new reagent for the determination of anionic surfactant sodium dodecyl benzenesulphonate (SDBS). The cyanine dye with an absorption maximum at 770 nm reacted with SDBS, causing significant hypochromism. Under the optimal conditions, the decreased absorption is proportional to the concentration of SDBS over the range 2.9 × 10⁻⁷–1 × 10⁻⁵ mol/L. The detection limit was 1.9 × 10⁻⁷ mol/L. The relative standard deviation for 1.43 × 10⁻⁶ mol LSDBS was 1.3% (n = 9). The proposed method was applied to determination of anionic surfactant in the river with 93–106% recovery levels. Preliminary research shows that the hypochromism is due to the formation of dye aggregate facilitated by SDBS.

Analytical Letters, 37(4), 711–723, 2004

Abstract

DIFFERENTIAL KINETIC SPECTROPHOTOMETRIC DETERMINATIONS OF ASCORBIC ACID AND L‐CYSTEINE BY PARTIAL LEAST SQUARES METHOD by Jahanbakhsh Ghasemi and Hamid R. Seraji, Department of Chemistry, Faculty of Sciences, Razi University, Kermanshah, Iran; Mohammad Noroozi and Majid Hashemi, Researches and Petroleum Engineering Center of Kermanshah, Kermanshah, Iran; Ali Jabbari, Department of Chemistry, Faculty of Sciences, K. N. T. University of Technology, Tehran, Iran

ABSTRACT: A kinetic spectrophotometric method was developed for simultaneous determination of ascorbic acid (AA) and L‐cysteine (Cys), based on detecting the colored final product. These compounds react differentially with Fe(III) in neutral medium, and the product of reduction. Fe(II), will form a colored compound with chromogenic reagent 1,10‐phenanthroline, which shows a maximum absorbance at 510 nm. The absorbance was measured at 510 nm every 2 sec from 10 to 190 sec, and the data obtained were processed by chemometric approach, partial least squares (PLS). The experimental calibration set was composed with 25 sample solutions using orthogonal calibration design for two component mixtures. The concentration ranges for AA and Cys were 2.00–11.82 and 1.50–14.99 ppm, respectively. The effect of pH and temperature was studied. The proposed method was successfully applied to the simultaneous determination of both analytes in pharmaceutical formulation.

Analytical Letters, 37(4), 725–737, 2004

Abstract

SOLID‐PHASE MICROEXTRACTION COUPLED WITH HIGH PERFORMANCE LIQUID CHROMATOGRAPHY‐FLUORIMETRIC DETECTION FOR THE DETERMINATION OF BISPHENOL A, 4‐n‐NONYLPHENOL AND 4‐tert‐OCTYLPHENOL IN ENVIRONMENTAL WATER SAMPLES by Yaqi Cai, Guibin Jiang, Jingfu Liu, Xia Liang, Ziwei Yao, Jiemin Liu, Jiyan Liu, and Qingxiang Zhou, Research Center for Eco‐Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing, 100085, China; Xia Liang and Qingxiang Zhou, Key Laboratory of Environmental Science and Engineering, Department of Chemistry, Xinxiang, Henan, 453002, China

ABSTRACT: Solid‐phase microextraction (SPME) coupled to high performance liquid chromatography and fluorimetric detection has been developed for the analysis of three endocrine disruptors: bisphenol A, 4‐n‐nonylphenol, and 4‐tert‐octylphenol. Several kinds of commercially available coating fibres were evaluated for their extraction efficiency to the target analytes and the carbowax/templated resin (CW/TPR) coating fibre was found to be the best one. The parameters affecting the extraction efficiency, such as absorption time, extraction temperature, pH values of the sample solutions, agitating rate, salting‐out effect, desorption mode, composition of the desorption eluent, and the flow rate of mobile phase at the desorption stage, were investigated and optimized. The chromatographic conditions were also examined. The developed method has been used to determine bisphenol A, 4‐n‐nonylphenol and 4‐tert‐octylphenol in several spiked natural water samples and good recovery results (93.9–108.2%) were obtained. Detection limits of 0.43, 0.16, and 0.29 ng mL⁻¹ for bisphenol A, 4‐n‐nonylphenol, and 4‐tert‐octylphenol, respectively, were achieved under the optimized conditions.

Analytical Letters, 37(4), 739–753, 2004

Abstract

STUDIES ON THE SUPRAMOLECULAR INTERACTION BETWEEN TETRAMETHRIN AND β‐CYCLODEXTRIN BY SPECTROFLUORIMETRY AND ITS ANALYTICAL APPLICATION by Wenli Liu, College of Life Science and Medicine Chemical Engineering, Taizhou University, Taizhou, People's Republic of China; Bo Tang, Yan Wang, and Zhenzhen Chen, College of Chemistry, Chemical Engineering and Materials Science, Shandong Normal University, Jinan 250014, Shandong Province, People's Republic of China.

ABSTRACT: The supramolecular interaction between tetramethrin and β‐cyclodextrin (β‐CD) has been studied by spectrofluorimetry. The results show that β‐CD reacts with tetramethrin to form an inclusion complex with an association constant of 40.3 L mol⁻¹. The composition of the complex is 1:1 (β‐CD:tetramethrin). Based on the significant enhancement of fluorescence intensity of tetramethrin in inclusion complex, a spectrofluorimetric method with high sensitivity and selectivity was developed for the determination of tetramethrin in aqueous solution. Under the optimum conditions, the complex had maximum excitation and emission wavelengths at 295 and 356 nm, respectively. The linear range of the method was 11–1500 ng mL⁻¹ with a detection limit of 3.4 ng mL⁻¹. The proposed method was successfully used to determine trace amount of tetramethrin in river water.

Analytical Letters, 37(4), 755–766, 2004

Abstract

PRECONCENTRATION‐SEPARATION OF HEAVY METAL IONS IN ENVIRONMENTAL SAMPLES BY MEMBRANE FILTRATION‐ATOMIC ABSORPTION SPECTROMETRY COMBINATION by M. Soylak, Erciyes Universitesi Fen‐Edebiyat Fakultesi, Kimya Bolumu 38039, Kayseri, Turkey; I. Narin, Nigde Universitesi Fen‐Edebiyat Fakultesi, Kimya Bolumu 51000, Nigde, Turkey; U. Divrikli and L. Elci, Pamukkale Universitesi Fen‐Edebiyat Fakultesi, Kimya Bolumu 20020, Denizli, Turkey; S. Saracoglu, Erciyes Universitesi Egitim Fakultesi 38039, Kayseri‐Turkey; M. Dogan, Hacettepe Universitesi Fen Fakultesi, Kimya Bolumu 06532, Ankara, Turkey

ABSTRACT: The preconcentration performance characteristics of cellulose nitrate membrane filter were investigated for the atomic absorption spectrometric determinations of traces metal ions in the environmental samples. The method was optimized for several parameters, including buffer pH, matrix, and type of the membrane. The investigated analyte ions were collected on cellulose nitrate membrane filter as their 8‐hydroxyquinoline (8‐HQ) (oxine) complexes. Then membrane filter was dissolved by using small amounts of concentrated nitric acid. The levels of copper, iron, cobalt, and cadmium ions in the final solutions were determined by flame atomic absorption spectrometry (FAAS). The recoveries of analytes were generally in the range of 94–102%. No influences have been observed from the matrix of the natural water samples. The presented procedure was applied for the determinations of analyte ions contents of natural waters, some ammonium salts, and microwave digested black tea samples with satisfactory results. The relative standard deviations of the determinations were below 9%. The method was verified by the analysis of two reference standard materials (GBW 07309 stream sediment and NRCC‐SLRS‐4 Riverine Water).

Analytical Letters, 37(4), 767–780, 2004

Abstract

ACCUMULATIVE SOLID‐PHASE SORPTION OF POLLUTANTS AS A METHOD FOR HYGIENIC AND ENVIRONMENTAL INSPECTION. III. DETECTION OF BIOWASTE USING BORONYLATED CARRIER by J. A. Khavkin, M. J. Roytman, and M. J. Khavkine, Technology Commercialization Corp. (TCC), 45 Tudor City Place, Suite 1619, New York, 10017, NY, USA

ABSTRACT: Detection of various biological waste (BW) with the aid of complex formation on surface of composition “Biowadet” is described. This composition contains unmodified poly(methylmethacrylate) (PMMA) granules with situated on their surface phenylboronic acid. Its hydrophobic part is dipped into hydrophobic polymer matrix, while hydrophilic boronic groups are orientated into water media. These groups can bind two nearly situated hydroxyls, that provides complex formation with various polyhydroxilic substances, for example with polysaccharides, lipopolysaccharides (LPS), glycoproteins, etc. These substances can be liberated by competition mechanism with glycerol in weakly acidic conditions. Periodate salts give oxidation of hydroxilic groups that gives a possibility to control experiment realization. ‘Biowadet’‐method may be applied to diverse purposes, such as an indication of reservoirs pollution, preparation of immunoglobulins (Ig), isolation of gram‐negative microbes (GNM) from water, etc. The simple method for environmental monitoring with application of blue dextran (BD) is proposed too.

Analytical Letters, 37(4), 781–788, 2004