Showing papers in "Analytical Sciences in 1989"
103 citations
TL;DR: These experiments have proved the principle applicability of a model which is based on the structural features of concentrated aqueous NaCl solutions and evidence of catalytic effects in peptide condensation reactions exerted by di- and trivalent metal ions.
Abstract: Peptide synthesis from amino acids has been shown to occur in aqueous solutions at high concentrations of sodium chloride and in the presence of Cu(II) after several days at 85°C, under nitrogen or air as well. Di- and tripeptides could be obtained in a series of experiments which have yet to be optimized. However, these experiments have proved the principle applicability of a model which is based on the structural features of concentrated aqueous NaCl solutions and evidence of catalytic effects in peptide condensation reactions exerted by di- and trivalent metal ions. Among the ions of Mg, Ca, Cr, Mn, Co, Ni, Fe, Cu, Zn and Cd, only copper was found to be active under these conditions. This leads to new aspects for possible prebiotic peptide syntheses based on a very simple system of only water, amino acids and mineral salts.
88 citations
TL;DR: The present membrane exhibits the theoretically expected absorbance response to ammonium ions in pH-buffered samples and dynamic range, selectivity coefficients, reproducibilities, and response times are promising in view of analytically relevant applications.
Abstract: A novel principle of an optical sensor (optode) has been realized in practice by combining NH4+-selective neutral ionophores of the macrotetrolide type, H+-selective neutral chromoionophores that drastically change their absorption spectrum upon protonation, and lipophilic anionic sites in the same plasticized PVC membrane. Such chemical sensors generally offer the advantages of a highly selective and reversible recognition of given ionic substrates and of a straightforward optical transduction of the recognition process. The present membrane exhibits the theoretically expected absorbance response to ammonium ions in pH-buffered samples. Dynamic range, selectivity coefficients, reproducibilities, and response times of the new optode system are promising in view of analytically relevant applications.
82 citations
TL;DR: In this article, the authors present a framework for the formation of l'acide polysilicique by reaction des acides molybdosiliciques reactifs, croissance des particules d'acides polysiliconicique, and reaction entre acides polysiciques.
Abstract: Etude generale: utilisation de la spectrophotometrie, de la chromatographie gaz-liquide des derives obtenus par trimethylsilylation, et de la chromatographie pour etudier la reaction. Mecanisme en 3 etapes: formation de l'acide polysilicique par reaction des acides molybdosiliciques reactifs, croissance des particules d'acide polysilicique par reaction des acides molybdosiliciques avec l'acide polysilicique, et par reaction entre acides polysiliciques. Influence du pH et de l'ion fluorure sur la vitesse de ces 3 processus
61 citations
TL;DR: These diaphorase-modified electrodes with an entrapped mediator were able to oxidize NADH catalytically at low applied potential and gave the current response to the substrate of the immobilized dehydrogenase atLow applied potential.
Abstract: Department of Agricultural Chemistry, Faculty of Agriculture, Kyoto University, Kyoto 606, Japan Diaphorase-immobilized carbon paste electrodes with an entrapped mediator were fabricated by covering the enzyme layer formed on the electrode surface with a dialysis membrane. The mediator (2-methyl-1, 4-naphthoquinone (VK), 1, 4-benzoquinone and ferrocene) was mixed in the carbon paste electrode. These diaphorase-modified electrodes with an entrapped mediator were able to oxidize NADH catalytically at low applied potential. Some characteristics of film-coated diaphorase-immobilized carbon paste electrodes with entrapped VK were investigated. Then, NAD+-dependent dehydrogenase (for glucose-6-phosphate, lactate, glycerol and ethanol) and diaphorase were co-immobilized on a carbon paste electrode containing both NAD+ and VK. The film-coated dehydrogenase and diaphorase co-immobilized electrodes with entrapped NAD+ and mediator (VK) gave the current response to the substrate of the immobilized dehydrogenase at low applied potential.
53 citations
TL;DR: In this paper, a continuous flow method was developed for the determination of chromium (VI) with lophine chemiluminescence using Activated Alumina for separation of Cr(VI) from metal ions such as Cu(II) and Cr(III).
Abstract: A continuous flow method was developed for the determination of chromium (VI) with lophine chemiluminescence. Activated alumina was effectively used for separation of Cr(VI) from metal ions such as Cu(II) and Cr(III) which interfered with the determination. The detection limit was 20 ng cm-3 without preconcentration and the relative standard deviation was 3% at 50 ng cm-3 of Cr(VI). The method was applied to the determination of Cr(VI) in water samples.
40 citations
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37 citations
TL;DR: In this article, a dilute aqueous micellar solution of poly(oxyethylene)=4-nonylphenyl=ether with oxyethylene units of 7.5 was separated into two phases (aqueous and surfactant) at room temperature.
Abstract: A dilute aqueous micellar solution of poly(oxyethylene)=4-nonylphenyl=ether with oxyethylene units of 7.5 (average, PONPE-7.5) was separated into two phases (aqueous and surfactant) at room temperature. The partition constants of thiazolylazo dyes and their metal chelates between the two phases were determined at 293K and an ionic strength of 0.1(NaClO4). Though a linear relationship was obtained between the partition constants of the chelating reagents in the extraction with PONPE-7.5 and those in the ordinary extraction with octanol, such a relationship was not obtained for the chelates. This suggested that the properties of the PONPE-7.5 phase as an extracting solvent were different from those of ordinary organic solvents.
34 citations
TL;DR: A reagent-impregnated resin prepared from 2-ethylhexyl hydrogen 2-hexylphosphonate (PC-88A) and Amber-lite XAD-7 beads was examined in order to apply it to the selective recovery of scandium as mentioned in this paper.
Abstract: A reagent-impregnated resin prepared from 2-ethylhexyl hydrogen 2-ethylhexylphosphonate (PC-88A) and Amber-lite XAD-7 beads was examined in order to apply it to the selective recovery of scandium. The distribution ratio of scandium to the present resin is extremely high (log D_??_6), even in highly concentrated acids. The separation factors between Sc(III) and other common metal ions including Fe(III) are sufficiently large to allow effective separations. The selective recovery of Sc(III) from the acid-leached solutions of wolframite and tin slag has been carried out by using the present resin as the column stationary phase. The retained Sc(III) is released from the resin quantitatively by elution with 4-methyl-2-pentanone. Scandium has been isolated as a precipitate by treating Sc-PC-88A complex with oxalic acid in ethanol.
34 citations
TL;DR: Les proprietes d'adsorption de l'oxyde de zirconium and de l 'oxyde of titane en chromatographie HPLC sont decrites.
Abstract: Les proprietes d'adsorption de l'oxyde de zirconium et de l'oxyde de titane en chromatographie HPLC sont decrites
TL;DR: In this article, high performance liquid chromatography was used for the determination of free fatty acids in the rabbit plasma by derivatization with monodansyl Cadaverine (MDC) at room temperature for 15min.
Abstract: Free fatty acids were determined by high performance liquid chromatography after derivatization with monodansyl Cadaverine (MDC) at room temperature for 15min in the presence of diethyl phosphorocyanidate as a coupling reagent The fluorescence properties (λex340nm, λem 518nm) of MDC-arachidic acid (C20:0) were identical to those of dansyl alanine The MDC derivatives of saturated and unsaturated fatty acids were completely separated within 50min by gradient elution on a TSK-gel 80TM ODS column When fluorometrically detected, the detection limits (S/N=3) of fatty acid were below 100fmol The calibration curves passed through the origin and gave good linearity in the range from 5 to 200pmol The method was successfully applied to the determination of fatty acids in the rabbit plasma This method would be quite useful for the analysis of various biological samples for thermolabile carboxylic acids, since it requires no heating procedure
TL;DR: These methods can be applied successfully to the chemiluminescent enzyme immunoassays for various hormones and drugs in biological fluids.
Abstract: Highly sensitive chemiluminescent enzyme immunoassays developed in our laboratory are reviewed. Oxidases, peroxidase and glucose oxidase, generating H2O2 can be assayed by isoluminol/microperoxidase or peroxyoxalate/fluorescent dye. β-D-Galactosidase is also assayed by chemiluminescence reaction based on the coupled enzyme reaction using lactose/glucose oxidase. β-D-Galactosidase can be measured by using o-nitrophenyl β-D-galactoside as substrate and chemiluminescence reaction of NADH after coupled enzyme reaction of galactose dehydrogenase. Sucrose and lucigenin are used as substrate and chemiluminescent reagent for the assay of invertase. Glucose-6-phosphate is determined by using glucose 6-phosphate as substrate and chemiluminescent assay of NADH. Alkaline phosphatase is assayed by using NADP+, alcohol dehydrogenase and hemiluminescence reaction of NADH. These methods can be applied successfully to the chemiluminescent enzyme immunoassays for various hormones and drugs in biological fluids.
TL;DR: In this article, trace amounts of silicate were determined on the basis of the coloration formed with molybdosilicate and Malachite green in aqueous solution.
Abstract: On the basis of the coloration formed with molybdosilicate and Malachite Green in aqueous solution, trace amounts of silicate were determined. In an acidic medium, silicate reacted with molybdate to form molybdosilicate, which reacted with Malachite Green to form a colored ion association complex. The color was stabilized by adding poly(vinyl alcohol). The molar absorptivity was 1.0×10(5)mol(-1)cm(-1) at 595nm, and the absorbance of the reagent blank was 0.089. The recommended concentration range of silicon was 0.1-5μg and the limit of detection was 0.01μg of silicon. Silicate in river and tap waters was determined.
TL;DR: In this article, the usability of column-switching techniques of high performance liquid chromatography is reviewed with special interest given to the enrichment and cleanup of biological samples, such as whole blood and tissue homogenates, by using a large-bore endfitting filter for the precolumn.
Abstract: The usability of column-switching techniques of high performance liquid chromatography is reviewed with special interest given to the enrichment and cleanup of biological samples. In Section 2, band broadening and a fully automated operation system are especially noted. In Sections 3 and 4, it is emphasized that the recovery of on-line solid extraction in a precolumn is quantitative (100%), depending upon the combination of the stationary phase and the mobile phase. In Section 5, are elucidated the deproteinization and recovery from protein-bound entities by a size exclusion coupled with internal-surface reversed-phase techniques or by hydrophobic interaction. These methods are extensively applied to the biological samples, such as whole blood and tissue homogenates, which contain minute particles, by using a large-bore endfitting filter for the precolumn.
TL;DR: In this article, a method based on the catalytic effect of vanadium(V) on the oxidative coupling reaction of 4-aminoantipyrine with N, N-dimethylaniline in the presence of bromate is presented.
Abstract: A catalytic-photometric method with a continuous-flow system is presented for the determination of nanogram amounts of vanadium in natural water. It is based on the catalytic effect of vanadium(V) on the oxidative coupling reaction of 4-aminoantipyrine with N, N-dimethylaniline in the presence of bromate. A higher sensitivity can be attained by using 1, 2-dihydroxybenzene-3, 5-disulfonic acid (Tiron) as an activator; vanadium(IV, V) at the 0.05- 2.0ng ml-1 level can be determined at a rate of 30 samples h-1. The method suffers few interferences and can be applied successfully to the determination of vanadium in natural water.
TL;DR: In this article, a synthese regroupant les progres techniques recents realises au Japon dans le domaine de l'analyse chimique d'especes minerales and organiques presentes dans l'eau de mer
Abstract: Article synthese regroupant les progres techniques recents realises au Japon dans le domaine de l'analyse chimique d'especes minerales et organiques presentes dans l'eau de mer
TL;DR: In this paper, the ion signals of oxide-forming elements (M+) and their monoxides (MO+) have been investigated as functions of inductively coupled plasma operating parameters, and an appropriate selection of the radio frequency power, carrier-gas flow rate and sampling depth was essential in order to minimize the signal ratio, SMO(+)/SM(+).
Abstract: The ion signals of oxide-forming elements (M+) and their monoxides (MO+) have been investigated as functions of inductively coupled plasma operating parameters. An appropriate selection of the radio frequency power, carrier-gas flow rate and sampling depth was essential in order to minimize the signal ratio, SMO(+)/SM(+). Signals SMO(+) and SM(+) decreased drastically with increasing radial distance from the plasma center. The signal ratios SMO(+)/SM(+) for various analytes, in consideration of partition functions and mass numbers, showed a linear relation with the oxide dissociation energies. Equivalent concentration data are also given for typical oxide interferences.
TL;DR: In this paper, the 1:1 aluminum-morin complex is fixed on a dextran-type cationic exchanger, and the fluorescence of the gel, packed on a 1-mm quartz cell, is measured directly using a solid-surface attachment.
Abstract: Morin (2′, 3, 4′, 5, 7-pentahydroxyflavone) has been used as a ligand in the fluorometric microdetermination of aluminum at the sub-μgl-1 level. A method has been developed which is based on ion exchanger fluorometry (IEF). The 1:1 aluminum-morin complex is fixed on a dextran-type cationic exchanger, and the fluorescence of the gel, packed on a 1-mm quartz cell, is measured directly using a solid-surface attachment. The concentration for the method ranges between 0.4 and 1.6μgl-1, although this can be diminished by increasing the sample volume. The method has been successfully applied to the determination of aluminum in natural water and offers several advantages in comparison with solution methods.
TL;DR: In this article, a monomolecular layer was covalently immobilized onto a tin(IV) oxide (SnO2) electrode via (1) 2, 4, 6-trichoro-1, 3, 5-triazine or (2) 3-aminopropyltriethoxysilane and glutaraldehyde, to give an amperometric glucose sensor.
Abstract: Glucose oxidase was covalently immobilized, as a monomolecular layer, onto a tin(IV) oxide (SnO2) electrode via (1) 2, 4, 6-trichoro-1, 3, 5-triazine or (2) 3-aminopropyltriethoxysilane and glutaraldehyde, to give an amperometric glucose sensor. The sensor thus obtained exhibited an order-of-magnitude higher specific sensitivity (i.e. sensitivity per immobilized enzyme molecule) and, even without continuous oxygen supply, a higher upper detection limit than a conventional type sensor carrying a crosslinked glucose oxidase membrane. The sensors showed a long-term stability (>1 month). When this sensor was applied to a flow injection glucose analyzer system, it showed a wide dynamic range (10-5-10-1M) and high analysis frequency (15 samples h-1 at a flow rate of 0.5ml min-1). The sensor was also used as a detector in a high performance liquid chromatograph system. The amount of glucose in a control serum was determined, in good agreement with the value determined by conventional methods.
TL;DR: In this article, the effect of tetraheptylammonium chloride, tetrahemmonium thiocyanate and thiourea on the extraction of platinum(II) is examined.
Abstract: The extraction of platinum(II) and/or palladium(II) with bis(2, 4, 4-trimethylpenty)phosphinodithioic acid from chloride solution has been studied. Extraction from heptane is more rapid than that from chloroform. The effect of tetraheptylammonium chloride, tetraheptylammonium thiocyanate and thiourea on the extraction of platinum(II) is examined. The rate of extraction of platinum(II) is considerably enhanced by the addition of thiourea. A rapid method for the separation of palladium(II) and platinum(II) based on the kinetic effect is proposed. Palladium(II) is first selectively extracted quantitatively into chloroform, and then platinum(II) is quantitatively (97±3%) extracted into heptane from 0.1M chloride solution containing thiourea.
TL;DR: In this paper, a method for direct determination of trace quantities of selenium by anodic stripping voltammetry has been developed, where a mercury-coated graphite wax electrode was used for this determination.
Abstract: A method for a direct determination of trace quantities of selenium by anodic stripping voltammetry has been developed. A mercury-coated graphite wax electrode was used for this determination. It is possible to determine 2×10-9M Se with a relative standard deviation (n=6) of 3.7% in solutions containing copper (up to 10% of the concentration of selenium). The presence of other elements, including tellurium, does not interfere. The presence of copper appears to be critical in the application of this method; in this case, if the quantity of selenium falls into the range 1.8_??_r_??_11, where r is the Cu/Se concentration ratio, selenium can be determined from the Cu-Se peak, which belongs to an intermetallic compound between copper and selenium. Considering that the known methods generally require an elimination of copper from the solution, the present method enables one to make such a determination in the presence of copper, even though it is within a short interval (1.8_??_r_??_11).
TL;DR: In this article, a method for the measurement of copper complexing ability of humic acids by using diethylaminoethyl Sephadex A-25 is reported, which can adsorb copper-humic acid complexes, but not free copper ions, and then determined by graphite-furnace atomic absorption spectrometry.
Abstract: A method for the measurement of copper complexing ability of humic acids by using diethylaminoethyl Sephadex A-25 is reported. Since the A-25 resin can adsorb copper-humic acid complexes, but not free copper ions, the free copper ions were fractionated and then determined by graphite-furnace atomic absorption spectrometry. Conditional stability constants and complexing capacities of the humic acids were estimated by Scatchard plot adapting to two-site model. The method could be applied to the humic acids from peat soil, and the copper complexing ability of the humic acids could be estimated sensitively and simply.
TL;DR: In this paper, the hydroxylated products of salicylate were identified by thin-layer chromatography and high performance liquid chromatography (HPLC) and the detection limit for 2, 5-dihydroxybenzoate was 0.555ng/ml (S/N=3).
Abstract: Salicylate was hydroxylated by hydroxyl radicals formed in the system composed of hypoxanthine-xanthine oxidase and a ferrous iron salt. The hydroxylated products of salicylate, namely, 2, 3-dihydroxybenzoate, 2, 5-dihydroxybenzoate and 2, 6-dihydroxybenzoate, were identified by thin-layer chromatography and high performance liquid chromatography (HPLC). The relative standard deviation was 7.98% (n=5) and the detection limit for 2, 5-dihydroxybenzoate formed from salicylate was 0.555ng/ml (S/N=3). This method was employed for the detection of hydroxyl radicals generated in polymorphonuclear leukocytes during stimulation by opsonized zymosan. The generation of hydroxyl radicals increased with increasing incubation period up to 40min.
TL;DR: In this article, a low power He-Cd laser-induced fluorescence (LIF) detection system for HPLC is described, which was developed for the detection of primary amines derivatized with naphthalenedialdehyde (NDA).
Abstract: The development of a convenient, low cost, low power He-Cd laser-induced fluorescence (LIF) detection system for HPLC is described. The system was developed for the detection of primary amines derivatized with naphthalenedialdehyde (NDA). The LIF system incorporates a fiber optic cell similar to the cell developed by Yeung and coworkers, which was modified in order to improve the S/Nratio. The LIF system exhibited detection limits of 0.75-1.2fmol which was comparable to the detection limits obtained for the derivatized amino acids with a high power argon ion LIF system and demonstrated a tenfold improvement in comparison to a commercial fluorescence detector. In addition, the LIF cell, collection optics and photomultiplier tube were mounted on a standard laboratory ringstand, which allowed the system to be easily moved. The applicability of the LIF system was demonstrated by derivatizing a human tear sample with NDA and subjecting it to HPLC analysis with LIF detection. Several amino acids were identified in the resulting chromatogram.
TL;DR: A function (FUMI) which describes the Shannon Mutual information in chromatography is derived and the optimal can be defined as the chromatogram which can transmit the maximal amount of mutual information in a unit time.
Abstract: A function (FUMI) which describes the Shannon mutual information in chromatography is derived. FUMI covers two subjects in one formula: (i) the degree of peak overlap and the noise level; (ii) the mathematical formalism of peak deconvolution and quantitation based on the one-dimensional Kalman filter for peak resolution. Computer simulation demonstrates that a sufficient amount of mutual information can be retrieved from overlapped peaks (Gaussian) through (i) observation and (ii) data processing. A practical advantage of FUMI is logical evaluation and optimization of chromatographic experiments without resort to experience: the optimal can be defined as the chromatogram which can transmit the maximal amount of mutual information in a unit time.
TL;DR: In this paper, a kinetic method is presented for the simultaneous determination of bromide and iodide based on the different catalytic behaviors during the oxidation of Pyrocatechol Violet by hydrogen peroxide in strongly acidic solution.
Abstract: A kinetic method is presented for the simultaneous determination of bromide and iodide based on the different catalytic behaviors during the oxidation of Pyrocatechol Violet by hydrogen peroxide in strongly acidic solution The reaction is monitored spectrophotometrically at 492nm The slope and the intercept at t=0 of the second-order plot are the parameters for the determination of iodide and bromide, respectively, which are simultaneously obtained by a single kinetic run Mixture of these anions, in the ranges 001-01mg I-′ bromide and 0005-005mg 1-′ iodide, can be determined within an error of ca 10%
TL;DR: Pre- and postcolumn derivatization methods employing recently-developed bifunctional fluorogenic reagents for high performance liquid chromatography have been demonstrated to be successful regarding both sensitivity and selectivity in the determination of bioactive substances and their related enzymes.
Abstract: Pre- and postcolumn derivatization methods employing recently-developed bifunctional fluorogenic reagents for high performance liquid chromatography have been demonstrated to be successful regarding both sensitivity and selectivity in the determination of bioactive substances and their related enzymes. The reagents were designed mostly based on the principle that vicinal or geminal, homo- or hetero-bifunctional (diamino, amino-imino, amino-sulfhydryl or amino-hydroxyl) compounds react with 1, 2-dioxo compounds (1, 2-ketols, glyoxals, 1, 2-diketones or 1, 2-quinones) or monooxo compounds (aldehydes) to yield fluorescent cyclic products. These reagents have been introduced into the quantification process of diverse bioactive substances in biological samples at the femtomole level.