Showing papers in "Analytical Sciences in 1986"

Adsorption of iron(III), gold(III), gallium(III), thallium(III) and antimony(V) on Amberlite XAD and Chelex 100 resins from hydrochloric acid solution.

Abstract: Adsorption behavior was investigated for five metals that form chloro-complexes on Amberlite XAD-4, XAD-7, XAD-8 and chelating resin Chelex 100 from hydrochloric acid solution. XAAD-7, XAD-8 and Chelex 100 adsorbed efficiently the metals; suitable hydrochloric acid concentrations were _??_6M for iron(III), _??_0.1M for gold(III), _??_5M for gallium(III), 0.1-8M for thallium(III) and 6-11M for antimony(V) (M=mol l-1). The metals were also adsorbed considerably on XAD-4 and Unicellex A {only iron(III) and antimony(V) were examined}. The extent of adsorption decreased with an increase in the concentration of the metals and the adsorption isotherms were found to be langmuir type. The capacities of XAD-7, XAD-8 and Chelex 100 for the metals were in the range 0.4-0.9mmol g-1 (weight after drying at 60°C). When hydrochloric acid is used to elute iron from Chelex 100, 1M hydrochloric acid is suitable but 10M is not. Possible adsorption mechanisms were discussed briefly.

Amperometric Biosensors Based on a Biocatalyst Electrode with Entrapped Mediator

Abstract: A mathematical model of a biocatalyst electrode with entrapped mediator is presented. The electrode is a benzoquinone (BQ)-mixed carbon paste electrode (CPE), on which glucose oxidase (GOD) is immobilized by coating with a polymer film or semipermeable membrane (s.m, a film-coated GOD-BQ-CPE). BQ is dissolved in the immobilized-enzyme layer(e.l.) to mediate the electron transfer between the electrode and the enzyme. The model is focused on the diffusion accompanied with enzyme reaction of substrate (D-glucose) and mediators (BQ and its reduced form) in the e.l. and the diffusion in the sm. The amperometric response of the electrode is analyzed as a function of transport, kinetic, and geometrical parameters and compared with experimental results. A glucose sensor based on a film-coated GOD-BQ-CPE has a wide concentration range of response and is not affected by oxygen in test solution. Biosensors for D-gluconate and ethanol based on film-coated gluconate dehydrogenase-BQ- and alcohol dehydrogenase-NAD-CPE′s, respectively, are presented.

Urea and glucose sensors based on ion sensitive field effect transistor with photolithographically patterned enzyme membrane

Abstract: A polyvinylpyrrolidone (PVP) based photocrosslinkable polymer has been used to make an enzyme membrane on an ion sensitive field effect transistor (FET). An enzyme and a lysine-rich polypeptide were added to a PVP solution containing 2, 5-bis(4′-azido-2′-sulfobenzal)-cyclopentanone as a photocrosslinking reagent. Using an integrated FET having two ion sensitive elements, an enzyme membrane on the gate surface of one of the two ion sensitive elements was formed by the spin-coating of the enzyme-PVP solution, followed by UV-irradiation on the gate area of the FET and development in a 3% glutaraldehyde solution. The method was used to make enzyme membranes for a urea sensitive and a glucose sensitive FET. Both sensors were evaluated by using a 0.3ml flow-through cell. The 100% response times were 25s and 15s for urea and glucose determination, respectively. The relative standard deviations for determination of urea and glucose with the sensors were less than 2% over the concentration range studied. The application of the urea sensitive FET to ex vivo serum assay is also described.

Fractional determination of dissolved selenium compounds of trimethylselenonium ion, selenium(IV) and selenium(VI) in environmental water samples.

Abstract: Fractional determination of trimethylselenonium ion(TMSe), Se(IV) and Se(VI) in water samples was studied by graphite furnace atomic absorption spectrometry. After coexisting cations formed a complex with thiosulfate to prevent being adsorbed on cation-exchange resin, separation and concentration of TMSe were carried out by column chromatography on Dowex 50 W-X8 resin. For concentration of inorganic selenium (Se(IV), Se(VI)) in water samples, column chromatography was carried out with an anion-exchange column using Dowex 1-X4 resin and the selenium were eluted simultaneously with 1M hydrochloric acid. Se(IV) in the eluent was extracted with dithizone solution under the condition of 4M hydrochloric acid. Se(VI) could be extracted with dithizone solution after the reduction to Se(IV) with hydroxylamine hydrochloride. In this procedure, the recovery of selenium was in the ragne of 86-102.8%, and the variation coefficient was 4.2-11.3%. The detection limit of TMSe was 10ng/21 and that of Se(IV) and Se(VI) was 5ng/l.

Surfactant-Selective Electrode Based on Poly (vinyl chloride) Membrane Plasticized with o-Nitrophenyl Octyl Ether

Abstract: Donnees sur une electrode a membrane donnant de tres bonnes reponses en presence d'agents de surface cationiques et anioniques

Chemiluminescence Flow Injection Analysis of Biological Compounds Based on the Reaction with Lucigenin

Abstract: Chemiluminescence reactions of lucigenin with various biological compounds were examined by a flow injection method. It was found that chemiluminescence from reducing sugars and related compounds was enhanced 100-times when incubated with sodium periodate prior to the reaction with lucigenin. The standard curve of glucose was linear over the range 50pmol-700pmol. Detection limits of glucose with and without treatment of sodium periodate were 50pmol and 50nmol, respectively. Corticosteroids and other compounds having an α-hydroxycarbonyl group in their molecule gave intensive chemiluminescence without treatment of sodium periodate. It was estimated that the α-hydroxycarbonyl group which converts to 1, 2-enediol was essential for the chemiluminescence reaction with lucigenin.

Automated Analysis of C3-C13 Hydrocarbons in the Atmosphere by Capillary Gas Chromatography with a Cryogenic Preconcentration

Abstract: An automatic system has been developed for the hourly analyses of trace hydrocarbons in the atmosphere. The system is based on cryogenic concentration followed by capillary gas chromatographic separation. In order to attain the quantitative transfer of the analytes to the capillary column and good chromatographic resolution, the analytes in the atmosphere were first collected in a small Tenax GC trap; then they were thermally desorbed into the cooled capillary column (-50°C). C3-C13 hydrocarbons could be analyzed quantitatively using this system. The detection limit for toluene was 50pg (70ppt in 175ml of sample air), and the precision was ±4% at the ppb level. The method has been successfully used to determine the diurnal variation of hydrocarbons in the atmosphere in the Tsukuba area.

Determination of Carboxybetaine Amphoteric Surfactants in Household and Cosmetic Products by High Performance Liquid Chromatography with Prelabeling

Abstract: A high performance liquid chromatographic (HPLC) method is described for the determination of carboxybetaine amphoteric surfactants in commercial household and cosmetic products. The surfactants are prelabeled with 4-bromomethyl-7-methoxycoumarin and then are separated by reversed phase HPLC with a gradient elution. The determination of carboxybetaines in shampoos was carried out by an internal standard method. The calibration curve was linear in the range from 0.007 to 4.6nmol. The relative standard deviation was found to be 1.0% for 0.46nmol injection. By using the proposed method, carboxybetaines in commercial household and cosmetic products were determined with high sensitivity and high selectivity.

Development of Directly Coupled Supercritical Fluid Chromatography-Mass Spectrometry with Self-Spouting and Vacuum Nebulizing Assisted Interface

Abstract: Supercritical fluid chromatograph (SFC) with a fused silica separation column (0.5mm I.D.×70cm) packed with ODS-Q3 (30-50μm) was directly coupled with a quadrupole mass spectrometer (MS) through a vacuum nebulizing interface originally developed for the combination of high performance liquid chromathograph (HPLC) with MS. Mixtures of hexane and ethanol were used as the mobile phase for SFC at a flow rate of 40μl/min (50kg/cm2). The column temperatures were maintained above the critical ones of the mobile phase between 260 and 280°C. Introduction of line filters to remove possible small particles in the SFC effluent and the subtle control of the optimum flow and/or the pressure for the SFC column enabled fairly long term stable operation for this SFC-MS system. Thus developed new system was successfully applied to the analysis of various samples such as styrene oligomers, phthalates, triglycerides, and polyethylene glycol derivatives.

Determination of Free and Total Catecholamines in Human Erythrocytes, Platelets and Plasma by High Performance Liquid Chromatography with Fluorescence Detection

Abstract: A simple and highly sensitive method for the determination of free and total (free+conjugated) catecholamines (norepinephrine, epinephrine and dopamine) in human erythrocytes, platelets and plasma is described which employs high performance liquid chromatography with fluorescence detection. Conjugated atecholamines are hydrolyzed by sulfatase-mediated reaction to the corresponding free amines. After cation exchange chromatography on a cartridge of a cation exchanger, Toyopak SP, catecholamines and isoproterenol (internal standard) in a sample are converted into the corresponding fluorescent compounds by reaction with 1, 2-diphenylethylenediamine. These compounds are separated on a reversed-phase column, TSK-gel ODS-120T, with isocratic elution using a mixture of water, methanol and acetonitrile containing a Tris•hydrochloric acid buffer (pH 7.0). The detection limit for each catecholamine is a. fmol/100-μl injection volume.

Vapor phase digestion of botanical samples with acids in sealed polytetrafluoroethylene bomb

Abstract: Pour le dosage des traces metalliques, description d'une methode de mineralisation en milieu acide avant dosage par spectrometrie d'emission a flamme ou spectrometrie d'absorption atomique. Application a des feuilles de the et du piment

Benzo thiacrown compounds as extraction-spectrophotometric reagents for univalent class b metal ions.

Abstract: Two new thiacrown compounds in which benzoazo groups are introduced as the chromogenic group, 4′-(p-hydroxyphenylazo)benzo-1, 4, 8, 11-tetrathiacyclopentadec-13-ene(III) and 4′-(2-hydroxy-5-chlorophenylazo)benzo-1, 4, 8, 11-tetrathiacyclopentadec-13-ene(VI), have been synthesized. Their characteristics as extracting and spectrophotometric reagents have been examined. Silver belonging to the univalent class b metals is extracted with reagent(VI) into 1, 2-dichloroethane. Its absorption maximum shifts to a much longer wavelength than that of the reagent itself. Neither class a and ab metals nor bivalent class b metals such as mercury(II) and palladium(II) were extracted at all. Only copper(II) of class ab metal is appreciably extracted with this reagent. It seems to proceed due to coordination to adjacent azo and phenol groups. In the presence of hydroxylamine sulfate, copper(I) is extracted into 1, 2-dichloroethane-amyl alcohol (4:1).

Determination of xylitol in the human serum and saliva by ion chromatography with pulsed amperometric detection.

Abstract: Pulsed amperometric detection with an ion chromatograph was used for the determination of xylitol in the human serum and saliva. Xylitol in serum and saliva was determined by using 0.15M sodium hydroxide as an eluent and D-mannitol as an internal standard. Xylitol and D-mannitol could be separated completely with retention times of 1.98min and 2.47min, respectively. Linearity of peak heights was 0.025 to 1.0μg/ml xylitol.The detection limit was 0.01μg/ml with an S/N=2. Mean recovery of xylitol ranged from 99.5 to 101.4%.Maximum concentrations of xylitol in serum and saliva were observed approximately 30min and 150min, respectively, after oral administration.

Gas Chromatographic Determination of Thiocyanate Ion in Biological Fluids Using Immobilized Phase-Transfer Catalyst for Derivatization

Abstract: A new gas chromatographic method was developed for the determination of thiocyanate ion in biological fluids. Fluid sample solutions deproteinized with acetone or methanol were centrifuged. After evaporation of the organic solvent of the supernatant by a rotary evaporator, thiocyanate ion was ethylated with ethyl iodide in an immiscible aqueous phase-organic phase system by using an immobilized phase-transfer catalyst. The resulting ethyl thiocyanate was determined by gas chromatography on a 20% polyethylene glycol 20M column. Either a flame ionization detector (FID) or a flame thermionic detector (FTD) was used. Thee method was capable of detemining thiocyanate ion concentrations in the range of 5 to 40μg/ml with the FID and 0.05 to 20μg/ml with the FTD. The detection limits were 1μg/ml with the FID and 0.01μg/ml with the FTD. The recoveries of thiocyanate ion added to cow′s milk, human saliva, and human urine samples were over 92% with good repeatability.

Catalytic Determination of Nanogram Amounts of Vanadium by the Oxidative Coupling Reaction of 4-Aminoantipyrine with N, N-Dimethylaniline

Abstract: A catalytic photometric method for determining a nanogram level of vanadium(IV) and vanadium(V) is proposed. The method is based on their catalytic effect on the oxidative coupling reaction of 4-aminoantipyrine with N, N-dimethylaniline in the presence of bromate and sulfosalycilic acid. The vanadium concentrations as low as 10-9M can be easily determined by measuring the absorbance of dye formed at a fixed time. The reproducibility of the method is satisfactory with the relative standard deviations of less than 3% and there are few interfering ions. The method has been applied to the determination of vanadium in natural waters.

Preconcentration of trace metal ions by complexation with ethylenediaminetriacetate-bonded silica gel

Abstract: Ethylenediaminetriacetate-bonded silica gel (ED3A-SG) was used for preconcentration of heavy metal ions prior to their determination by inductively coupled plasma-atomic emission spectrometry (ICP-AES). ED3A-SG was prepared by reacting silica gel with N-(trimethoxysilylpropyl)ethylenediaminetriacetate. Coastal seawater up to 2dm3, buffered at pH 5.0, were passed through a column filled with 250mg of ED3A-SG. Then the metal ions adsorbed were eluted with 10cm3 of 0.5mol dm-3 hydrochloric acid. The concentrate thus obtained was analyzed by ICP-AES.

Determination of strontium in seawater by capillary type isotachophoresis

Abstract: A new analytical procedure for strontium in seawater was developed: a capillary-type isotachophoresis which applies the ion exchange method is used. Large amounts of coexisting sodium, magnesium, calcium and potassium interfered with the isotachophoretic measurement of strontium. Therefore, after the seawater sample was passed through the column packed with a sodium cation-exchange resin, calcium was removed with 5.0×10-3M EDTA solution adjusted to pH 6.6 and then strontium was eluted with 5.0×10-3M GEDTA solution adjusted to pH 10.0. Magnesium was eluted little by little with EDTA solution but was not with GEDTA solution. The isotachophoretic determination was performed with an analyzer equipped with a potential gradient detector and a 40-cm- long main column connected to a 10-cm-long precolumn. The leading electrolyte was a mixed solution of 0.01M hydrochloric acid and 0.1% hydroxypropyl methylcellulose, of which the pH was adjusted to 9.0 with tris- (hydroxymethyl)aminomethane. A terminating electrolyte was 0.01M sodium hexanoate. A linear working curve was obtained for artificial seawater samples containing up to 16mg/l of strontium. The proposed method was applied to the determination of strontium in surface seawater samples collected around the coastal area of Osaka Bay in September, 1985. Reproducible values were obtained by the standard addition method.

Simultaneous Determination of Three Species by Flow Injection Analytical Method Using Enzyme-Immobilized Open-Tubular Reactors

Abstract: A simultaneous determination of three species by a flow injection analytical (FIA) method using enzyme-immobilized open-tubular reactors in parallel is described. The design of the optimal geometry of the FIA system is especially important to avoid overlap of any pairs of peaks. Ours was carried out based on the Taylor-Aris equation. Despite a somewhat complex splitting-confluence flow system, reproducible results were obtained in the simultaneous determination of L-lactate, β-D-glucose and glycerol by the detection of the resulting common product, NADH. Assignment of the enzyme reactors to the channels should be made by taking into account the concentration ranges of the analytes to be measured and the differences in the rates of individual enzyme reactions.

Determination of Potassium in River Water by Solvent Extraction- Flow Injection Analysis

Abstract: Spectrophotometrie avec utilisation du dibenzo-18-crown-6 et du derive dechlore du tropeoline

Determination of antimony in river water by hydride-generation atomic absorption spectrometry.

Abstract: Trace antimony in river water was determined by hydride-generation atomic absorption spectrometry. The water was concentrated after the addition of mineral acids. Siliceous residues deposited during the concentration were solubilized with hydrofluoric acid and expelled by evaporation in the presence of sulfuric acid. After chelating resin separation, the effluent was acidified with sulfuric acid to ionize the hydrolyzed antimony. The accuracy checked with a biological standard reference material was satisfactory when the insoluble residues in the material were treated with hydrofluoric acid after acid digestion. Antimony contents in the water ranged between 0.1 and 0.9ng ml-1.

Photoacoustic Spectrometry Coupled with Total Internal Reflection Technique: Theory and Experiment

Abstract: Theoretical expressions of photoacoustic signals generated in liquid in normal and oblique incidences of a laser beam are derived by modifying the Rosencwaig and Gersho theory for the investigation of distribution profiles of light absorbing species at solid-liquid interfaces. Expressions for both incidences show that the photoacoustic signal magnitudes are dependent on instrumental, solvent and thermal diffusion factors. The results expected from the expressions are in agreement with experimental results. This modified theory is expected to be applicable to liquid samples with any transparency.

Spectrophotometric Determination of Gold(III) by Formation Of Dicyanoaurate(I) and Its Solvent Extraction with Methylene Blue

Abstract: The proposed determination of gold(III) is based on the formation of dicyanoaurate(I) and its extraction into 1, 2-dichloroethane as an ion-pair with Methylene Blue. The optimum pH range for the formation of dicyanoaurate(I) is 2.2-7.2 under the conditions described. The absorbance of the extract is stable for at least 4 days in a glass-stoppered tube. The apparent molar absorptivity for gold is 1.08×105l mol-1 cm-1 and the Sandell sensitivity for 0.001 absorbance is 1.8×10-3μgAu cm-2 at 657nm. Linear calibration graphs are obtained over the range 2×10-7-8×10-6M gold(III) (0.4-15.8μgAu in 10ml); at the 6×10-6M gold(III) level, the relative standard deviation is 0.2%.

Electrogenerated chemiluminescence detector for flow injection analysis

Abstract: A new kind of detector system based on electrogenerated chemiluminescence (ECL) was devised for flow injection analysis. The flow through type of electrolytic cell was modified to observe the ECL. The quartz optical window was set in front of the working electrode (Pt plate). The observed luminescence intensity was amplified by using a lock-in amplification technique. The preliminary examination of the whole system was performed using luminol with a strong ECL. The injection of a sample solution in a carrier solution of sodium carbonate caused a peak-shaped luminescence at the electrode. Next the determination was performed for non-luminescent compounds after the pre-labeling with luminol. It was found that oligo peptides or bovine serum albumin can be determined by ECL method. Though, the sensitivity and the reproducibility of ECL method are almost comparable to existing methods, it has the advantage that two kinds of quantities, the luminescence intensity and the electrolytic current, can be obtained at the same time.

Resolution of differential pulse polarography: comparison with a.c. polarographic techniques

Abstract: A relationship was derived for the resolution of differential pulse polarography as a function of the pulse amplitude and various parameters of the electrode reaction of the simultaneously present components(number of electrons exchanged in the electrode reaction, half-wave potentials). The resolution was found to be higher at small pulse amplitudes and large difference in the half-wave potentials. Resolution is higher when the number of electrons involved in the electrode reaction of both the measured and the interfering species are larger and it is mainly affected by the latter. The resolution of differential pulse polarography was found to be inferior to that of fundamental harmonic and second harmonic a.c. polarography.

Continuous Determination of Cyanide in Waste Water with Ion Selective Electrode and Gas-Liquid Separation

Abstract: The waste water sample is pumped at the flow rate of 4cm3 min-1 to the mixing joint, where a reaction solution (5×10-3M bismuth nitrate-containing sodium acetate buffer at pH 5.0) is mixed at the rate of 1cm3 min-1. Then the mixture containing hydrogen cyanide is fed into a gas-liquid separator. The hydrogen cyanide permeates through a Teflon membrane (0.80μm pore size, 0.08mm thick) into an absorption solution (0.02% sodium hydroxide) flowing at 24cm-3 h-1. The cyanide ion produced is measured with the cyanide selective electrode. The response time is about 1.3min at a concentration of 1×10-4M cyanide. The Nernst equation is valid with a relative standard deviation of less than 2.8% in the range between 1×10-3 and 1×10-6M. The lower detection limit is 1×10-7M (2.6 CN- ppb). This method can detect free cyanide ion and indirectly metal cyano complexes whose stability constants are below 1017.

Chemiluminescent assay of hydrogen peroxide using leuco-2',7'-dichlorofluorescein-peroxyoxalate.

Abstract: A new chemiluminescence system for the determination of hydrogen peroxide (H2O2) was developed. The assay principle of this system is that fluorescent chromophore produced from leuco-2′, 7′-dichlorofluorescein (LDCF) by the reaction with H2O2 and peroxidase can be made luminescent by addition of bis(2, 4, 6-trichlorophenyl) oxalate (TCPO) and H2O2 dissolved in acetonitrile. So, H2O2 could be determined at a concentration of 10-9 to 10-5M as the amount of fluorescent chromophore, dichlorofluorescein (DCF). To show one application of this system, peroxidase activity was determined in the range of 10-3 to 1U/ml. Uric acid in presence of uricase was also determined in the range of 5×10-5 to 5×10-2mg/dl.