Good Preclinical Bioanalytical Chemistry Requires Proper Sampling from Laboratory Animals: Automation of Blood and Microdialysis Sampling Improves the Productivity of LC/MSMS.
Fuming XIE, Craig S. BRUNTLETT, Yongxin ZHU, Candice B. KISSINGER, and Peter T. KISSINGER
Bioanalytical Systems, Inc. (BASi), 2701 Kent Avenue, West Lafayette, IN 47906-1382, USA
The preclinical bioanalytical process with animal models begins with sampling biological fluids and tissue. The goal is to understand oral absorption kinetics, distribution, metabolism, excretion, blood brain barrier penetration, drug-drug interactions, and the influences on biomarkers, hematology, electrophysiology, cardiology, blood pressure and behavior. An overview is obtained by periodic blood sampling of 8 - 12 samples over a total time span of 10 - 24 h. Urine, feces, bile and microdialysates can augment the information available from whole blood. In today's preclinical environment, the majority of samples are processed by LC/MSMS augmented by robotic sample preparation tools. These tools save labor and improve precision for smaller volume/lower concentration samples. Our laboratories have been engaged in a project that is focused on improving both the quality and throughput for laboratory animal studies, while providing for reduced numbers of animals and enhanced animal comfort. We have implemented a robotic system that can accomplish most of the above goals for laboratory rats, dogs and primates. Studies with mice are at an earlier stage, but feasibility has been demonstrated. This presentation is a progress report on this evolving research program in cooperation with multiple pharmaceutical and drug development companies. We will illustrate results and discuss future directions.
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Reviews
Surface-analytical Studies on Environmental and Geochemical Surface Processes
Haruhiko SEYAMA* and Mitsuyuki SOMA**
*Environmental Chemistry Division, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan
**Institute for Environmental Sciences, University of Shizuoka, 52-1 Yada, Shizuoka 422-8526, Japan
The surface chemical compositions of solid samples from environmental and geological sources can differ from the bulk or average compositions, because of changes caused by adsorption, dissolution, oxidation, etc. Accordingly, analytical information on surface layers is important for a better understanding of the environmental chemistry involving solid surfaces. The rapid development of surface-analytical techniques has enabled us to probe the surface chemistry of environmental and geological solid samples of complex composition. This article demonstrates some examples of important items of information that can be obtained by applying surface-analytical techniques, such as X-ray photoelectron spectroscopy and secondary ion mass spectrometry, to environmental and geological samples. The surface analysis of fly ashes, soils, sediments and weathered silicate minerals is reviewed.
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Original Papers
A Screening Method for Estrogens Using an Array-Type DNA Glass Slide
Sung Bae KIM, Takeaki OZAWA, and Yoshio UMEZAWA
Department of Chemistry, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
A new screening assay was described for the determination of endocrine disrupting chemicals (EDCs), such as synthetic estrogens, with an array-type DNA glass slide having characteristics of 1) a high sample throughput, 2) a compact size allowing a small sample volume, and 3) a sensitive determination based on the estrogen-dependent binding of the human estrogen receptor α(hERα) with its estrogen responsive element (ERE; Vit. A2 gene promoter). We devised a glass slide on which a thin agarose gel was mounted. Avidin was then covalently immobilized on each well of the glass slide after the gel was activated by a NaIO4 solution. Also, the biotinylated ERE as a DNA probe was immobilized on the gel layer through avidin-biotin binding. After the estrogen-dependent binding of a yellow fluorescent protein-fused hERα (YFP-hERα) to ERE on the gel layer, the fluorescence intensity of YFP-hERα quantitatively extracted into the gel was directly determined with a fluorescence microplate reader. Pre-incubation of YFP-hERα with estrogen at 37°C for 30 min enhanced the estrogen-dependent hERα-ERE binding. The determined hormonal activities of estrogens on the interaction of YFP-hERα with ERE were as follows in their decreasing order: diethylstilbestrol (DES) > 17β-estradiol (E2) = ethynylestradiol (EE2) > 4-hydroxy tamoxifen (OHT) > clomiphene (Clo). The present method provides a sensitive estrogen-dependent dose-response curve down to ∼10-13 M in the case of DES. This method will become a competitive alternative to the conventional in vitro assays, such as a DNA-binding assay using radioisotopes.
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Monitoring of Oxidation Steps of Ascorbic Acid Redox Reaction by Kinetics-Sensitive Voltcoulometry in Unsupported and Supported Aqueous Solutions and Real Samples
Jozef ORLICKÝ,* Katarína GMUCOVÁ,** Ilja THURZO,** and Juraj PAVLÁSEK***
*Institute of Molecular Physiology and Genetics, Slovak Academy of Sciences, Vlarska 5, 833 34, Bratislava, Slovak Republic
**Institute of Physics, Slovak Academy of Sciences, Dúbravská cesta 9, 845 11 Bratislava, Slovak Republic
***Institute of Normal and Pathological Physiology, Slovak Academy of Sciences, Vlárska 5, 833 34 Bratislava, Slovak Republic
Aqueous solutions of ascorbic acid in unsupported and supported aqueous solutions and real samples were studied by the kinetics-sensitive double-step voltcoulommetric method with the aim to contribute to a better understanding of its behavior in biological systems. The data obtained from measurements made on analytes prepared in the laboratory, as well as those made on real samples (some commercial orange drinks, flash of the fresh fruits) point to the redox reaction of L-ascorbic acid (L-AH2) being very sensitive to both the presence of dissolved gaseous species (O2, CO2) and the ionic strenght in the analyte. Either the dissolved gaseous species, or the higher ionic strength caused by both the presence of supporting electrolyte and increased total concentration of ascorbic acid, respectively, give birth to the degradation of LAH2. Naturally, the highest percentage of L-AH2 was spotted in fresh fruit.
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Differential Pulse Adsorptive Stripping Voltammetric Determination of Dinoseb and Dinoterb at a Modified Electrode
Mallipattu SREEDHAR, Tukiakula Madhusudana REDDY, Kami Reddy SIRISHA, and Srinivasulu Reddy Jayarama REDDY
Electrochemical Research Laboratories, Department of Chemistry, Sri Venkateswara University, Tirupati-517 502, India
A sensitive adsorptive stripping voltammetric method for the determination of dinitrophenolic herbicides, dinoseb (DSB) and dinoterb (DTB) at a bare carbon paste electrode (CPE) and a clay modified carbon paste electrode (CMCPE) was developed. A systematic study of various experimental conditions, such as the pH, accumulation variables and composition of a modifier on the adsorptive stripping response, were examined by using differential pulse voltammetry. A significant improvement was observed in the sensitivity by using the present method with CMCPE. When CMCPE was used, a linear response was obtained over the concentration range 2 x 10-10 to 3 x 10-7 M and 6 x 10-10 to 6 x 10-7 M with lower detection limits of 1 x 10-10 M and 5.4 x 10-10 M for dinoseb and dinoterb, respectively, at an accumulation time of 100 s. The interference from other herbicides and ions on the stripping signals of both compounds was also evaluated. The described method was applied to estimate of the dinoseb and dinoterb in environmental samples.
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Selective Measurement of Gaseous Hydrogen Peroxide with Light Emitting Diode-Based Liquid-Core Waveguide Absorbance Detector
Jianzhong LI and Purnendu K. DASGUPTA
Department of Chemistry and Biochemistry, Texas Tech University, Lubbock TX 79409-1061, USA
Atmospheric H2O2 is typically determined by enzymatically mediated fluorogenic reactions that do not discriminate between H2O2 and organic peroxides. Reactions of Ti(IV) with H2O2 has also been the basis of colorimetric measurements of H2O2 but is too insensitive. A more sensitive determination is possible with the Ti(IV)-4-(2-pyridylazo)resorcinol (PAR) complex, however, unreacted PAR must be chromatographically separated. A titanium(IV)-porphyrin complex, oxo[5,10,15,20-tetra(4-pyridyl)porphyrinato]titanium(IV) [TiO(tpypH4)4+], (TiTPyP) was introduced for the measurement of aqueous H2O2. In this paper, we show that TiTPyP can be used for measuring H2O2(g), it does not respond to CH3HO2. With a proper membrane collector, practically there is no interference from concurrently present gaseous SO2 and O3. The approach permits a S/N = 3 limit of detection (LOD) of 26 pptv with a 50 mm path liquid core waveguide (LCW) absorbance detector and a light emitting diode based light source. This is adequate for real atmospheric measurements.
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Determination of Elemental and Ionic Compositions for Diesel Exhaust Particles by Particle Induced X-ray Emission and Ion Chromatography Analysis
Katsumi SAITOH,*1 Koichiro SERA,*2 Tadashi SHIRAI,*3 Tatsuji SATO,*4 and Matsuo ODAKA*4
*1 Environmental Research & Information Center of Akita Prefecture, 3-1-1 Sanno, Akita 010-8572, Japan
*2 Cyclotron Research Center, Iwate Medical University, 348 Tomegamori, Takizawa 020-0173, Japan
*3 Tokyo Dylec Co., Ltd., 29 Daikyo-cyo, Shinjuku, Tokyo 160-0015, Japan
*4 National Traffic Safety and Environment Laboratory, 7-42-27 Jinndaiji-Higashi, Chofu, Tokyo 182-0012, Japan
The purpose of this study is to clarify the chemical characterization of PM2.5 and PM10 in diesel exhaust particles (DEP). Sampling of PM2.5 and PM10 in DEP was carried out in November 1999 using an automobile exhaust testing system at the National Traffic Safety and Environment Laboratory, with a diesel truck (engine type: direct injection, displacement: 7961 cc, carrying weight: 2020 kg, equivalent inertia weight: 5600 kg) placed on a chassis dynamometer. Sampling conditions included idling, constant speed of 40 km/h, M-15 test pattern and 60%-revolution/40%-load of maximum power. Samples were collected on a polycarbonate membrane filter (Nuclepore®, pore size: 0.8 µm) using a MiniVol Portable Air Sampler (Airmetrics Co., Inc.). The concentrations of several elemental and ionic species in the PM2.5 and PM10 samples were determined by particle induced X-ray emission (PIXE) and ion chromatography analysis. PIXE analysis of the PM2.5 and PM10 samples revealed 15 elements, of which Na, Mg, Si, S, Cl, Ca, Fe and Zn were found to be the major components. Ionic species were Cl-, NO2-, NO3-, SO42-, Na+, NH4+, K+ and Ca2+. Concentrations of elements and ionic species under the sampling condition of 60%-revolution/40%-load were highest in comparison with those of the other sampling conditions. The elemental and ionic species data were compared for PM2.5 and PM10; PM2.5 concentrations were 70% or more of PM10 concentrations for the majority of elements, and concentrations of ionic species in PM2.5 and PM10 were almost identical.
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Determination of Trace Metal Complexes by Natural Organic and Inorganic Ligands in Coastal Seawater
Ghiasse ABBASSE, Baghdad OUDDANE, and Jean Claude FISCHER
Université des Sciences et Technologies de Lille, Laboratoire de Chimie Analytique et Marine (ELICO) UMR CNRS 8013, Bât. C8 2ème étage, 59655 Villeneuve d'Ascq Cedex, France
It is well-documented that organic compounds form strong complexes with most metals in aquatic systems, and that seawater is a complex medium which contains a large variety of organic and inorganic ligands, including colloidal matter. We suggest that most trace metals are complexed in seawater and that some inorganic metals complexes are either labile or not stable. In contrast, metal-organic complexes are often stable and need various and specific treatments to be dissociated. In this paper we try to illustrate a good tendency of some trace metals to be complexed by organic ligands in seawater. A solid-phase extraction method was applied using a C18 column as a resin that is able to separate metals complexed by neutral organic ligands, and the chelamine resin to separate metal species that are present as labile inorganic complexes. The determination of total dissolved metal concentrations was achieved by formatting a metal-8-hydroxyquinoline complex, followed by adsorption on C18 columns and ICP-AES analysis.
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Identification of Electrical Degradation Products of 4-Chlorophenol in Water
Jongki HONG,* Do-Gyun KIM,* Jung-Ju SEO,* Chulhyun LEE,** Chaejoon CHUNG,** and Kwang-Wook KIM***
*Hazardous Substance Research Team, Korea Basic Science Institute, 126-16 Anam-Dong, Sungbuk-Ku, Seoul 136-701, Korea
**Nucleic Magnetic Resonance Research Team, Korea Basic Science Institute, 52 Eoeun-Dong, Yoosung-Ku, Daejeon, 305-333, Korea
***Korea Atomic Energy Research Institute, Yoosung-Ku, Dukjin-Dong, Daejeon, Korea
The electrical decomposition of 4-chlorophenol in water was examined with iridium dioxide doped on a titanium electrode. A number of electrical degradation products of 4-chlorophenol, such as hydroquinone and chlorohydroquinone via the addition of hydroxyl radicals, and dichlorophenol through addition of chlorine radical, were observed as major products. Moreover, hydroxylated chlorobiphenylethers, hydroxylated dibenzo-p-dioxin/furans and hydroxylated chlorobiphenyls formed by a dimerization process during the electrolysis process of 4-chlorophenol were also observed. On the other hand, benzoquinone, muconic acid and aldehyde derivatives that were further oxidative products of hydroquinone formed by photocatalysis process, were not observed. The electrical decomposition products of 4-chlorophenol were trimethylsilylated and then identified by gas chromatography–mass spectrometry. The degradation rate of 4-chlorophenol in water by iridium oxide electrode was measured against the electrical process duration. After iridium electrical process for 120 min, about 50% of 4-chlorophenol was converted into a number of products through oxidation processes. On the basis of the identified products, the degradation pathways of 4-chlorophenol under electrolysis process were proposed.
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Simultaneous Analysis of Carbamate Pesticides in Tap and Raw Water by LC/ESI/MS
Nobuko MAKIHATA, Tatsuhiko KAWAMOTO, and Kiyoshi TERANISHI
Hyogo Prefectural Institute of Public Health and Environmental Sciences, Kobe 652-0032, Japan
Ten carbamate pesticides including four suspected endocrine disruptors, methomyl, benomyl (carbendazim), aldicarb and carbaryl, were simultaneously analyzed by LC/ESI/MS. The influence of the matrix on the variation of the ion signal intensities of (M + H)+ and adduct ions was investigated. Although the intensities of three oxamyl ions changed depending on the matrix, the variation in the concentration calculation of oxamyl was reduced by using the sum total of the area value of two ions. The limits of the quantitation of ten pesticides without a concentration procedure were from 0.4 - 30 µg/l. The solid-phase recovery rates of ten pesticides spiked into tap water and raw water were in the range of 69 - 111%. Using this method, the concentrations of the pesticides in tap and raw water sampled at 14 monitoring points in Hyogo Prefecture were determined. Carbendazim in three raw water samples and carbofuran in one of these three samples were detected at low concentrations (less than 0.32 µg/l).
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Aquacyanocobalt(III)-Cobyrinate as a Key Compound in NO2-Sensitive Polymeric Liquid Membranes
Tomas NEZEL,* Gleb ZHYLYAK,* Gerhard J. MOHR,** and Ursula E. SPICHIGER-KELLER*
*Centre for Chemical Sensors, Swiss Federal Institute of Technology, Technoparkstr. 1, 8005 Zürich, Switzerland
**Institute of Physical Chemistry, The Friedrich-Schiller University of Jena, 07743 Jena, Germany
The reactions within a recently introduced NO2-sensitive polymeric membrane based on aquacyanocobalt(III)-cobyrinate are described. The detailed reaction mechanism was investigated in three ways: using UV/VIS-spectroscopy, determining the reaction products and investigating the influence of other gases. It could be shown that the membrane's high sensitivity and selectivity derives from the remarkable reaction of NO2 with this cobyrinate derivative, which yields nitric and nitrous acid. This reaction can be transduced with a consecutive protonation of the included chromoionophore into an optical signal, which allows the detection of NO2 in the ppb-range.
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Simultaneous Determination of Copper(II) and Cobalt(II) by Ion Chromatography Coupled with Chemiluminescent Detection
Chao LU,* Jin-Ming LIN,* Carmen W. HUIE,** and Masaaki YAMADA***
*Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P. O. Box 2871, Beijing 100085, China
**Department of Chemistry, Hong Kong Baptist University, 224 Waterloo Road, Kowloon Tong, Hong Kong, China
***Department of Applied Chemistry, Graduate School of Engineering, Tokyo Metropolitan University, 1-1 Minami-Ohsawa, Hachioji, Tokyo 192-0397, Japan
In the absence of any special luminescent reagents, a weakly chemiluminescent emission was observed during the decomposition of hydrogen peroxide, catalyzed by transition-metal ions, such as Cu(II) and Co(II), in basic aqueous solution. The chemiluminescent intensity was significantly enhanced by the addition of ethyldimethylcetylammonium bromide and uranine. The signal-to-noise ratio (S/N) was proportional to the concentrations of Cu(II) and Co(II). Based on these phenomena, a flow-injection chemiluminescent method for the simultaneous separation and determination of Cu(II) and Co(II) was developed. The detection limits of the present chemiluminescent method for Cu(II) and Co(II) were 7.5 and 0.01 ng/ml, respectively. After ion chromatographic separation of Cu(II) and Co(II) by an IonPac CS5A column with oxalic acid and lithium hydroxide monohydrate as the eluent, the present chemiluminescent system was used as a post-column detector for these two transition metal ions in natural water samples.
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Determination of Butamyrate Citrate in Cough Preparations by Derivative UV Spectrophotometry and High Performance Liquid Chromatography
Eleftheria T. MALLIOU, Constantinos G. ANTONIOU, and John E. KOUNDOURELLIS
Laboratory of Pharmaceutical Analysis, School of Pharmacy, Aristotelian University, 54124 Thessaloniki, Greece
Derivative spectrophotometric procedures and an isocratic high performance liquid chromatographic method for the determination of butamyrate citrate (Sinecod®, Safarol®) in cough syrups have been developed. In the spectrophotometric method, direct measurement of the drug at its absorption maxima is impossible because of interference from different absorbing excipients. Extraction of butamyrate citrate was performed with n-pentane/isopropyl alcohol. Quantification was carried out through the use of 1D derivative at a trough depth of 253.6 nm where interferences from other coextracted compounds are negligible. The extraction efficiency expressed as a % recovery and precision were assessed by fortifying placebo syrup(s) with known amounts of the compound. Also, a reversed phase high performance liquid chromatographic method was used with a mobile phase containing 0.015 M aqueous tetraethylammonium hydrogen sulfate, methanol and acetonitrile 40:30:30 adjusted to pH 3.50 with ammonium hydroxide. The retention behavior of butamyrate citrate as a function of both pH and salt concentration in the aqueous portion of the mobile phase was investigated. Quantification was achieved with UV detection at 258 nm based on peak area. The HPLC method clearly separates the analyte from its degradation products derived after storage of samples under different stress conditions such as acid, alkaline, temperature, oxygen and light. The described methods were successfully applied to the determination of butamyrate citrate in commercial pharmaceutical products and in placebo syrups prepared in the laboratory with good accuracy and precision. The results of the present study show that the use of the derivatives and the HPLC procedure provide precise and sensitive methods for the determination of the compound in pharmaceutical formulations.
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Flow Injection Analysis of Hydrogen Peroxide Using Glass-Beads Modified with Manganese(III)-Tetra(4-carboxyphenyl)porphine Derivative and Its Analytical Application to the Determination of Serum Glucose
Masaki MIFUNE,* Katsuyoshi SUGIMOTO,* Akimasa IWADO,** Hiromichi AKIZAWA,** Noriko MOTOHASHI,*** and Yutaka SAITO*
*Faculty of Pharmaceutical Sciences, Okayama University, Tsushima-Naka, Okayama 700-8530, Japan
**Graduate School of Sciences and Technology, Okayama University, Tsushima-Naka, Okayama 700-8530, Japan
***Kobe Pharmaceutical University, Motoyamakita-machi, Higashinada, Kobe 663-8179, Japan
A flow injection analysis system of hydrogen peroxide was developed. The present system is based on measuring of the absorbance of a quinoid dye formed by the reaction between aminoantipyrine and 2H2O2 (catalyzed by peroxidase), which produces quinoid dye and 4H2O. A column packed with aminopropyl-glass beads modified with a manganese(III)-tetra(4-carboxyphenyl)porphine derivative (Mn-TCPPG column), which has peroxidase-like activity, was used in place of an immobilized peroxidase column in the above reaction. The linear range of the calibration curve was 0.4 - 80 µg/ml hydrogen peroxide. The relative standard deviation of this system was 2.97% (n = 100, 10 µg/ml hydrogen peroxide 20 µl injection). The Mn-TCPPG column has sufficiently stability for the continuous injection of hydrogen peroxide untill 100 times. The advantageous feature of the Mn-TCPPG column was a less-electrostatic interaction between the mother glass beads and the anionic chromogen or quinoid dye formed and the stability in terms of the storage, temperature and moisture. The determination of serum glucose was achieved by attaching an immobilized glucose oxidase column to this system without deproteinization.
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Electrochemiluminescent Determination of L-Cysteine with a Flow-Injection Analysis System
Liande ZHU, Yingxiu LI, and Guoyi ZHU
State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry,
Chinese Academy of Sciences, Changchun 130022, P. R. China
A flow-injection electrochemiluminescent method for L-cysteine determination has been developed based on its enhancement of the electrochemiluminecence of luminol at a glassy carbon electrode. This method is simple and sensitive for cysteine determination. Under the selected experimental parameters, the linear range for cysteine concentration was 1.0 x 10-6 - 5.0 x 10-5 mol/l, and the detection limit was 0.67 µmol/l (S/N = 3). The relative standard deviation for 11 measurements of 1.0 x 10-5 mol/l cysteine was 4.5%. The proposed method has been applied to the detection of cysteine in pharmaceutical injections with satisfactory results.
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Sensitive and Simple Cloud-point Preconcentration Atomic Absorption Spectrometry: Application to the Determination of Cobalt in Urine Samples
Jamshid L. MANZOORI and Ghasem KARIM-NEZHAD
Department of Analytical Chemistry, Faculty of Chemistry, The University of Tabriz, Tabriz, Iran
A new approach for developing a cloud-point extraction-flame atomic absorption spectrometric method has been described and used for the determination of cobalt. In this approach, water was removed from the final diluted surfactant rich phase obtained in cloud-point extraction procedure. The results indicated that removing water from this phase increased the enhancement factor by 4-fold. 1-(2-Pyridylazo)-2-naphthol (PAN) and octylphenoxypolyethoxyethanol (Triton X-114) were used as a hydrophobic ligand and a nonionic surfactant, respectively. The chemical variables affecting the preconcentration step were optimized. The effect of the water concentration in the final diluted methanolic surfactant solution on the analytical signal was investigated. The results showed that the analytical signal decreased by 30% and 52% in 15% and 25% water concentrations in methanol, respectively. An enhancement factor of 115 was obtained for cobalt extracted from only 10 ml of a sample. The detection limit obtained under the optimal condition was 0.38 µg l-1. The proposed procedure was applied to the determination of cobalt in urine samples.
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Determination of Lead in Seawater by Flow-Injection On-line Preconcentration-Electrothermal Atomic Absorption Spectrometry after Coprecipitation with
Iron(III) Hydroxide
Junichi NAKAJIMA, Yoshihiro HIRANO, and Koichi OGUMA
Department of Materials Technology, Faculty of Engineering, Chiba University, Yayoi-cho, Inage, Chiba 263-8522, Japan
A flow-injection on-line preconcentration-electrothermal atomic absorption spectrometric (ETAAS) method coupled with a coprecipitation method has been developed for the determination of lead in seawater. The combination of two preconcentration procedures, coprecipitation with iron(III) hydroxide and solid-phase extraction with a lead-selective resin, Pb·SpecTM, allowed the determination of lead at the ng kg-1 level. Lead in 250 g of a sample solution was collected by coprecipitation with 10 mg of iron. The precipitate was dissolved in 25 ml of 1 mol l-1 nitric acid; then, a 4-ml aliquot of the sample solution was introduced into the flow-injection system to preconcentrate and separate lead from iron on a Pb·Spec microcolumn. The sorbed lead was eluted with a 1.0 x 10-4 mol l-1 EDTA solution. The 30-µl portion of the eluate corresponding to the highest analyte concentration zone was injected into a graphite furnace. The overall enhancement factor was about 200 for 250 g of the sample. The average and standard deviation of ten blank values obtained were 1.7 ng and 0.38 ng, respectively. The recovery was 93.7 ± 5.0% for seawater spiked with 20 ng kg-1 lead. The proposed method is applicable to the analysis of seawater for lead at slightly higher levels.
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Determination of Chromium(III) and Total Chromium in Water by Derivative Atomic Absorption Spectrometry Using Flow Injection On-line Preconcentration with a Double Microcolumn
Han-wen SUN, Wei-jun KANG, Shu-xuan LIANG, Jing HA, and Shi-gang SHEN
College of Chemistry and Environmental Science, Hebei University, Baoding, 071002, China
A rapid and sensitive method has been proposed for the sequential determination of chromium(III) and total chromium in water samples by flame atomic absorption spectrometry combined with a flow injection on-line preconcentration on a double-microcolumn. The chromium(III) and total chromium in samples were retained on a double-microcolumn with a cation exchange resin, respectively, and eluted directly into a nebulizer by 3 mol L-1 HNO3. The characteristic concentration (gives a derivative absorbance of 0.0044) and the detection limit (3sigma) for chromium were 0.512 µg L-1 and 0.647 µg L-1 for a preconcentration time of 1 min, respectively. This is an improvement of 20 and 14-times than those of conventional FI-FAAS. The proposed method allows the determination of chromium in the range of 0 - 90 µg L-1 with a relative standard deviation of 3.63% at the 10 µg L-1 level. The method has been applied for the analysis of chromium in reference water of National Research Center for Certified Reference Materials (GBW08607) and other water samples with satisfactory results.
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Modified Babington Nebulizer for Inductively Coupled Plasma Atomic Emission Spectrometry
Hirofumi ISOYAMA,* Tetsuo UCHIDA,** Takashi NAGASHIMA,* and Osamu OHIRA*
*Toki Municipal Institute of Ceramics, Hida 287-3, Hida-cho, Toki, Gifu 509-5403, Japan
**Department of Applied Chemistry, Nagoya Institute of Technology, Gokiso-cho, Showa, Nagoya, Aichi 466-8555, Japan
A PTFE Babington nebulizer equipped with a hood was investigated for inductively coupled plasma atomic emission spectrometry in conjunction with a PTFE cyclone chamber, in order to nebulize various sample solutions containing high salts, hydrofluoric acid and/or suspended solid. A hood of 3 mmφ (nozzle side) - 5 mmφ (outlet side) and 6 mm in length gave a comparable or higher sensitivity compared to a system with a commercially available concentric nebulizer and a glass cyclone chamber. Moreover, the present nebulizer was fully interchangeable with a concentric one at normal argon pressure, attaining sufficient stability, a short wash-out time and good nebulizing of high matrices solutions. The present system was successfully applied to the determination of trace impurities in highly pure silica powders.
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Photoacoustic Determination of Iron in Corn Meal
O. DELGADO-VASALLO,*1,*2 J. L. PEÑA,*2 E. San Martíin MARTÍNEZ,*3 A. CALDERÓN,*3 G. Peña RODRÍGUEZ,*3,*4 M. R. Jaime FONSECA,*3 and E. MARIN*1
*1 Universidad de La Habana, Facultad de Fíisica-IMRE, San Lázaro y L, Vedado 10400, Habana, Cuba
*2 CICATA-IPN, Unidad Altamira, Km 14.5 Carretera Tampico-Puerto Industrial Altamira, C. P. 89600, Altamira, Tamaulipas, México
*3 CICATA-IPN, Unidad Legaria, Legaria 694, Col. Irrigación, 11500 México D. F.
*4 U. F. P. S. Departamento de Física, A. A. 1055, Cúcuta, Norte de Santander, Colombia
We report here on the use of the photoacoustic technique for the determination of low concentrations of total iron in corn meal samples. The determination of this element in food is of considerable interest because several foods are currently enriched with it at proper levels in order to increase the resistance of people, after consumation, to several diseases, such as anemia. The proposed technique is based on an open photoacoustic cell configuration in conjunction with a suitable colorimetric method. We applied it to a measurement of the total iron concentration in corn meal samples. The results agree very well with those obtained using a conventional spectrophotometric method, showing the possibilities of new experimental methodologies based on photothermal methods to perform this kind of study, with the advantage of a higher sensitivity and increment of the range of appreciable absorbance.
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Distribution of the Amplitude of the Self-Oscillation of the Electrical Potential Difference Observed in an Organic Phase of a Water-Oil-Water Liquid Membrane System
Toshifumi YOSHIDOME, Jun TAKAHAMA, Masaru MITSUSHIO, and Morihide HIGO
Department of Applied Chemistry and Chemical Engineering, Faculty of Engineering, Kagoshima University,
1-21-40 Korimoto, Kagoshima 890-0065, Japan
The electrical potential differences were measured at various points in an organic phase of a water-oil-water liquid membrane system in which self-oscillations of an electrical potential difference occurred across a three-phases-liquid membrane by using an H-shaped cell. The electrical potential difference oscillated in the direction through the two aqueous phases, but not in its vertical direction. The amplitude of the self-oscillation greatly changed around the place where the horizontal tube was connected to the vertical tube, which had no surfactant.
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Determination of EDTA Species in Water by Second-Derivative Square-Wave Voltammetry Using a Chitosan-Coated Glassy Carbon Electrode
Changzhi ZHAO,* Yuzhen PAN,* Chunxiang HE,** Zhen GUO,* and Licheng SUN*
*State Key Laboratory of Fine Chemicals, Dalian University of Technology, 158-40 Zhongshan Rd., Dalian 116012, China
**Department of Chemistry, Liaoning Normal University, 580 Huanghe Rd., Dalian 116029, China
Based on the adsorption of Fe(EDTA)- on a chitosan-coated glassy carbon electrode, a second-derivative square-wave voltammetry for the determination of the EDTA species in water samples was investigated. The measuring range of EDTA was from 6.0 x 10-7 to 5.0 x 10-5 mol/L with a correlation coefficient of 0.998 and a detection limit of 2.8 x
10-7 mol/L. The relative standard deviation was less than 6.2% (n = 5) and the recovery was in the range of 98 - 105% for the determination of practical samples. The result was consistent with that from the HPLC method.
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Liquid Chromatographic Separation and Determination of Aromatic Sulfonates in an Aquatic Environment Using a Photodiode Array and Electrospray Ionization-Mass Spectrometer as Detectors
R. Nageswara RAO, N. VENKATESWARLU, Sara KHALID, and R. NARASIMHA
HPLC Group, Division of Analytical Chemistry, Discovery Laboratory, Indian Institute of Chemical Technology, Tarnaka, Hyderabad-500 007, India
A simple and rapid method involving high-performance liquid chromatographic separation, followed by photodiode array (PDA) and electrospray ionization-mass spectrometric (ESI-MS) detection of aromatic sulfonates in waste-water effluents of industrial units producing optical whitening agents, has been developed. The separation was achieved on a reversedphase Hypersil C18 column using gradient elution of a mobile phase consisting of 0.05 M ammonium formate-methanol with decreasing concentration of the buffer at room temperature. The minimum detection limits were determined to be in the range of 0.2 - 1.8 x 10-9 g using PDA and ESI-MS detectors.
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Preparation of Ferrocyanide-Imprinted Pyridine-Carrying Microspheres by Surface Imprinting Polymerization
Isamu FUJIWARA,* Mizuo MAEDA,** and Makoto TAKAGI***
*Center for Waste Water Treatment, Yamaguchi University, Yoshida, Yamaguchi 753-8511, Japan
**Bioengineering Laboratory, RIKEN (Institute of Physical and Chemical Research), Wako 351-0198, Japan
***Department of Chemical Systems Engineering, Graduate School of Engineering, Kyushu University, Hakozaki, Fukuoka 812-8581, Japan
Ferrocyanide-imprinted pyridine-carrying microspheres were prepared using ferrocyanide ions as a template. This method is based on a surface imprinting technique from the seed emulsion that consisted of 4-vinylpyridine (functional monomer), styrene, and butyl acrylate and a water mixture polymerization by a radical initiator. The ferrocyanideimprinted microspheres had about 200 times higher adsorption affinity over the non-imprinted microspheres in ferrocyanide (template) ion adsorption. This imprinted microspheres also adsorbed other tripolyphosphate, pyrophosphate, and phosphate anions much more strongly than the non-imprinted microspheres did, but were not particularly specific in ferrocyanide ion adsorption.
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Determination of Thiobarbituric Acid Adduct of Malondialdehyde Using On-line Microdialysis Coupled with High-Performance Liquid Chromatography
Jenn-Yuan SHEU,* Hsiao-Pei KU,* Wei-Chang TSENG,* Min-Tzu CHEN,* Li-Yu TSAI,** and Yeou-Lih HUANG**
*Graduate Institute of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
**School of Technology for Medical Sciences, Kaohsiung Medical University, Kaohsiung, Taiwan
An on-line analytical system for the continuous monitoring of malondialdehyde (MDA) was developed. This method involves the use of microdialysis perfusion, on-line derivatization and on-line HPLC analysis. This method gave a linear response for MDA concentrations and HPLC peak areas in the range from 0.051 µM to 2.43 µM. The intra-day (RSD = 1.6 - 10.5%) and inter-day (RSD = 1.1 - 9.3%) precisions were acceptable. The average in vitro probe recovery of MDA standard was 18.4 ± 1.0%. The detection limit was 0.03 µM, corresponding to 0.6 pmol for an injection volume of 20 µl. This method was used for in vitro peroxidation investigations, which provided evidence for elevated MDA levels following the incubation of metal ions to a linoleic acid solution.
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Flow-Injection Determination of Ornidazole by Chemiluminescence Detection Based on a Luminol-Ferricyanide Reaction
Yi LV, Zhujun ZHANG, Deyong HE, and Yufei HU
Institute of Analytical Science, Department of Chemistry, Southwest Normal University, Beibei, Chongqing 400715, P. R. China
A flow-injection analysis (FIA) with a chemiluminescence detection method was developed for the determination of ornidazole based on the inhibition intensity of chemiluminescence from the luminol-ferricyanide system. Under the condition of 1.0 x 10-3 mol/L luminol and 5.0 x 10-6 mol/L potassium ferricyanide, the response to the concentration of ornidazole is linear from 0.2 µg ml-1 to 10 µg ml-1, and a detection limit of 0.05 µg ml-1 can be obtained. This method has been successfully applied to the determination of ornidazole in pharmaceutical preparations.
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Simple Method of Paroxetine Determination Using a Single Channel FIA with No In-line Reaction Process
Göksel ALTIOKKA and Kevser KIRCALI
Department of Analytical Chemistry, Faculty of Pharmacy, Anadolu University, 26470 Eskisehir, Turkey
A flow-injection analysis (FIA) of paroxetine hydrochloride (PRX), a selective serotonin reuptake inhibitor (SSRI) currently used as an antidepressant drug, is described. A 0.1 mol dm-3 acetate buffer at pH 3.07 was found to be the best solvent. The analyte was detected at 293 nm. The calibration equation was linear over the range of 1.07 x 10-6 to 5.35 x 10-6 mol dm-3. The limit of detection (LOD) and the limit of quantitation (LOQ) were 3.2 x 10-7 and 9.5 x 10-7 mol dm-3, respectively. The proposed method was applied to the determination of PRX in pharmaceutical preparations. The results were compared with those obtained by a conventional batchwise UV-spectrophotometry.
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Kinetic-Catalytic Determination of Vanadium(IV) Using Methyl Orange-Bromate Redox Reaction
Ghodratollah ABSALAN and Yosef ALIPOUR
Department of Chemistry, Faculty of Sciences, Shiraz University, Shiraz 71454, Iran
Determination of V(IV) based on its catalytic effect on the reaction between Methyl Orange and bromate in the presence of citric acid was studied. The calibration curve obtained by fixed-time method was linear in the range of 2.5 - 300 ng ml-1. By use of slope method, a calibration curve containing two linear portions were obtained. Using fixed-time and slope methods, we obtained detection limits of 0.8 and 1.5 ng ml-1, respectively. Fe2+, As(III), V(V) and Hg2+ interfered. The method was successful for analysis of water samples.
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Instrumental Achievements
Crystal Structure and Synthesis of 17α-(5-Chlorovaleroyloxy)-16β-methylpregna-4,6-diene-3,20-dione
Manuel SORIANO-GARCÍA,* Elena RAMÍREZ,** Eugene BRATOEFF,** Marisa CABEZA,** and Gerardo AGUIRRE-HERNÁNDEZ***
*Departamento de Bioestructura, Instituto de Química, UNAM, Circuito Exterior, Ciudad Universitaria, Coyoacán, México D. F. 04510, México
**Departamento de Farmacia, Facultad de Química, UNAM, Ciudad Universitaria, Coyoacán, México D. F. 04510, México
***Centro de Graduados e Investigación del Instituto Tecnológico de Tijuana, Blvd. Industrial S/N, Tijuana, Baja California, México
C27H37O4Cl is orthorhombic, P212121. The unit-cell dimensions at 293 K are a = 7.1388(15), b = 12.9836(14), c = 26.665(10)Å, V = 2471.5(10)Å3, Dx = 1.239 g/cm3, and Z = 4. The R value is 0.070 for 1458 observed reflections. The A, B, C and D rings occur in distorted envelope, distorted half-chair, chair, and envelope and a half-chair conformations. The molecules in the crystal are packed at the normal van der Waals distances.
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Crystal Structure of (2,2'-Bipyridine-N,N')(2,2',2"-Triaminotriethylamine-N,N',N",N'")nickel(II) Diperchlorate
Yung-Chan LIN,** Tian-Huey LU,* Fen-Ling LIAO,** and Chung-Sun CHUNG**
*Department of Physics, National Tsing Hua University, Hsinchu, Taiwan 300, R. O. C.
**Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan 300, R. O. C.
An X-ray structure determination shows that the Ni(II) ion is a distorted six-coordinated octahedron by four nitrogen atoms of the tetradentate tren ligand constituting the equatorial square base, and by two nitrogen atoms of the bidentate bpy ligand in a cis position. The two six-membered rings of bpy are coplanar and almost pararell. The tetradentate ligand consists of three five-membered chelate rings in gauche coformations. The Ni-N(tren) bond lengths of this complex are almost equivalent to the reported values.
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Instrumental Achievements
Crystal Structure of (5,14-Methyl-7,12-dimethyl-1,4,8,11-tetraazadiiminecyclotetradecylene-N,N',N",N'")nickel(II) Bis-(diisopropyldithiophosphate) Complex
Fangfang JIAN, Kui JIAO, Faqian LIU, and Qingxiang WANG
New Materials & Function Coordination Chemistry Laboratory, Qingdao University of Science and Technology, Qingdao, 266042, P. R. China
The macrocyclic tetradentate Ni(II) compound was obtained in a reaction and determined by X-ray diffraction. The crystal structure shows that the molecule is centrosymmetric, and Ni atom located in a square planar coordination environment. The two [(iPrO)2PS2]- anions are outside the macrocycle complex to balance. The Ni-N bond lengths are in the range of 1.906(2) to 1.950(2)Å.
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Instrumental Achievements
Crystal Structure of {1,4-Bis[1-(3,5-dichlorophenolato-2-ylmethyl)-ylpropylamino-κ2N,O]piperazine-κ2N,N'}cobalt(II)
Koji KUBONO,* Naoki HIRAYAMA,** Hisao KOKUSEN,*** and Kunihiko YOKOI*
*Division of Natural Science, Osaka Kyoiku University, Kashiwara, Osaka 582-8582, Japan
**Department of Chemistry, Faculty of Science, Kanazawa University, Kanazawa 920-1192, Japan
***Department of Environmental Engineering, Kanazawa Institute of Technology, Nonoichi, Ishikawa 921-8501, Japan
The X-ray crystal structure of the title complex, Co(Cl2bprpi) is described. In this complex the Co(II) center displays a distorted octahedral coordination geometry. The piperazine ring exhibits boat conformation, forming chelate rings and capping the Co atom. The N2-Co1-N3 angle is 69.41(15)°, extremely smaller than 90°. Because the small angle causes a large steric hindrance, the piperazine ring can be effective as an ion size-recognition site. The molecular structure is stabilized by intramolecular N-H···O hydrogen bonds and Cl···H contacts.
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Instrumental Achievements
Crystal Structure of 7,8-Dihydroxy-4-methylcoumarin
Hiromasa KUROSAKI,* Rakesh K. SHARMA,** Masami OTSUKA,*** and Masafumi GOTO*
*Faculty of Pharmaceutical Sciences, Kumamoto University, Oe-honmachi 5-1, Kumamoto 862-0973, Japan
**Department of Chemistry, University of Delhi, Delhi-7, India
***Graduate School of Pharmaceutical Sciences, Kumamoto University, Oe-honmachi 5-1, Kumamoto 862-0973, Japan
The structure of 7,8-dihydroxy-4-methylcoumarin was determined by an X-ray diffraction method. The compound crystallized in the triclinic space group P1, Z = 2, with a = 7.631(2), b = 9.456(5), c = 7.075(3)197, α= 103.13(3), β= 91.84(3), γ= 68.21(3)°, and V = 460.9(3)Å3. The X-ray crystal structure was also compared with those of 5,7-dihydroxy-4-methylcoumarin and 7-hydroxy-4-methylcoumarin.
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