A platinum electrode was illuminated with an intermittent Ar⁺ laser beam in a flowing solution from the front side of the electrode. The current induced by this laser illumination was recorded as a function of electrode potential with a lockin amplifier and was directly observed with an oscilloscope. Experimental results for the [Fe(CN)₆]^4-, [Fe(CN)₆]^3-, Fe²⁺ and Fe³⁺ solutions indicated that the laser heating of the electrode promotes or depresses the electron transfer process, depending on the standard entropy change of the electrode reaction, promotes the mass transfer process and induces adsorption or desorption of anions. Further, the induced current was proportional to the concentration and strongly depended on the chopping frequency and the flow rate. This laser electrochemical (LEC) detection can be used as a new
electrochemical detector in electroanalytical chemistry.

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In order to investigate whether coexisting H₂S, H₂and N₂affect the δ¹³C value, we measured the δ¹³C and δ¹⁸O values of CO₂ gas mixed in arbitrary ratios with each gas. H₂S and H₂increase the δ¹³C value, while N₂produces no change. On the other hand, the δ¹⁸O values are not affected by the presence of H₂S, H₂or N₂. These results suggest that the hydrogen of H₂S or H₂may convert a part of CO₂⁺to HCO₂⁺in the ionization chamber, which could increase each CO₂mass number
by one. The shifting effect from mass 44 to mass 45 is more pronounced than that from mass 45 to mass 46, since the amount of ⁴⁴CO₂ is much larger than ⁴⁵CO₂or ⁴⁶CO₂. This is likely to be the reason why the δ¹³C value increases with increasing hydrogen/CO₂ ratio, while the δ¹⁸O value shows little change, irrespective of the hydrogen/CO₂ ratio. In order to minimize the coexisting H₂S effect, we have improved the purification method of CO₂ by using a CuCl₂ solution trap to remove H₂S.

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Traces of Co, Cu, Ni, Th and U in high-purity zinc metal were determined by inductively coupled plasma mass spectrometry (ICP-MS) in combination with flow-injection (FI) on-line matrix separation (FI-ICP-MS). The anion-exchange separation method of an HCl system was applied to the separation of Ni, Co, Cu, Th and U from zinc matrix. The matrix element, zinc, was adsorbed on an anion-exchange (BIO•AD AGl-X8) mini-column (2.0mm i.d.×300mm bed length), while the analytes were directly introduced into the ICP-MS. The following detection limits (in ng g^-1) were obtained: Ni, 3.1; Co, 1.2; Cu, 4.0; Th, 0.12 and U, 0.48. The reproducibility has proved to be satisfactory with a relative standard deviation of less than 5% (at the 10ng ml^-1 level, n=3). The method was successfully applied to determining trace impurities in three 6 and 7 nines grade of high-purity zinc metals and in three standard reference materials of high-purity zinc metal samples (from NIST).

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After microwave acid digestion of botanical standards and the coprecipitation of lead at pH>1.0 as fluorides using calcium as a carrier, a lead pyrrolidin-1-yldithioforrnate complex was extracted into a small volume of chloroform. Direct nebulization of the chloroform extract into a fuel-lean air-acetylene flame gave a sensitive signal intensity. The background-corrected signal intensity obtained by nebulizing 60μl of the extract was 4.0 fold compared with that obtained by nebulizing 100μl of an aqueous solution. The present method was successfully applied to the determination of lead in the following botanical-certified reference materials: National Institute of Standards and Technology, Standard Reference Materials (NIST SRMs) 1571 Orchard Leaves, 1572 Citrus Leaves and 1573 Tomato Leaves. The results agreed well with the certified values (reference values: 45±3, 13.3±2.4, 6.3±0.3; found: 43.9±1.0, 13.0±0.1, 6.1±0.2μg g^-1, respectively).

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he separation of niobium and tantalum was examined by using macroporous polyacrylate polymer beads (Amberlite XAD-7) as an adsorbent in hydrofluoric acid-hydrochloric acid mixtures. The adsorption of niobium and tantalum was measured as a function of each acidic concentration; it was found that niobium showed a lesser adsorption than did tantalum, and that both metals could be released by weakly acidic solutions. Column chromatography was carried out using the resin as a stationary phase and acidic solutions of appropriate concentrations as a mobile phase. The niobium and tantalum were successfully separated from each other, and application to a multielemental sample containing both metals was also demonstrated. By using this chromatographic system, trace tantalum was effectively removed from the niobium matrix.

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The cation-exchange behavior of antimony(III) on Dowex 50W-X8 (H⁺ Form) resin using a mixed-solvent system of 0.2M HBr and acetone, methanol, ethanol, 1, 4-dioxan or tetrahydrofuran has been studied. The separation of antimony(III) from binary mixtures containing alkali metals, alkaline earth metals as well as some other associated elements was carried out by selective elution with 0.2M HBr in 80% acetone. The method is applicable to the analysis of synthetic mixtures, alloys and pharmaceutical samples.

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A flotation-spectrophotometric method for the separation and determination of Fe(III) in fresh and natural water samples has been developed. The method is based on the colored complex which is formed between Fe(III) and 2- carboethoxy-1, 3-indandione sodium salt (CEIDNa). The colored 1:3 (Fe:reagent) complex is quantitatively floated with oleic acid (HOL) surfactant in the pH range 3-6. The complex in the scum is measured directly for iron at λ=490nm. Beer′s law is obeyed over the concentration range 2.8-39μg of Fe(III) in 4ml of HOL surfactant. The molar absorptivity is 0.65×10⁴ 1mol^-1cm^-1. The different factors affecting the flotation and determination of Fe(III) have been investigated. The determination of Fe(III) after selective flotation increases the sensitivity and eliminates the effect of foreign ions. The method was successfully applied to detect as little as 1ppb Fe in 20ml samples of natural water after flotation with HOL surfactant.

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For cobalt(III), nickel(II), copper(II) and zinc(II) 4-(2-thienyl)-4-thioxo-1, 1, 1-trifluoro-2-butanonates (STTA) the capacity factors in an octyl- or an octadecyl-bonded silica gel and a methanol-water system of reversed-phase high- performance liquid chromatography (RP-HPLC) were compared with the distribution ratios (D_B) of those chelates in the batch method. The distribution behavior of the metal-STTA chelates in the batch method almost corresponded to the retention behavior of those in RP-HPLC. Moreover, the dependence of log D_B on log[STTA] in the methanol-water phase of the batch method was almost consistent with the dependence of log D on log[STTA] in the organic phase in chelate extraction. These situations suggest that the distribution behavior of metal chelates in liquid-liquid extraction may be helpful to estimate their chromatographic behavior in RP-HPLC.

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Previous to the extraction, preparation of a solution containing a quantitative amount of Fe²⁺ was performed by electrolytic reduction of Fe³⁺ at a potential of 0.1V vs. Ag/AgCl reference electrode. Solvent extraction of iron(II) was carried out using 4, 4, 4-trifluoro-1-(2-thienyl)-1, 3-butanedione (2-thenoyltrifluoroacetone, Htta) into various organic solvents: heptane, benzene, 4-methyl-2-pentanone, pentyl acetate, 1-hexanol and 1-heptanol. In order to avoid the oxidation of iron(II), the organic and aqueous phases were bubbled with nitrogen gas before extraction; the iron(II) solution was also handled in a nitrogen-filled glove box. For every solvent except 1-heptanol, almost all the extracted species was Fe^III(tta)₃. Analysis of the extraction equilibrium and UV-visible spectra of the organic phase showed that iron was extracted as Fe^II(tta)₂ by using 1-heptanol. In this extraction system, the extraction constant was 10^-3.45.

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Chloride salts of cobalt(III) complexes of 1, 4, 8, 11-tetraazacyclotetradecane-5, 7-dione (L¹) and 6-(2-(2-pyridyl)ethyl)-1, 4, 8, 11-tetraazacyclotetradecane-5, 7-dione (L²), acting as a water-soluble anion carrier capable of a selective recognition of nitrite and thiocyanate, were isolated, and their solid state structures and properties in water were studied. IR spectroscopic and X-ray crystallographic approaches have clarified that the isolated complexes have iminol tautomeric structures, in which the amide oxygen atoms are protonated, but the amide nitrogen atoms bound to cobalt(III) are deprotonated. Conductivity and pH titration studies on aqueous solutions of the complexes have revealed that the iminol groups act as a strong acid in water; the acid-dissociation constants of the water molecule axially coordinated to the cobalt(III) are 10^-6.65 and 10^-7.01 for the L¹ and L² complexes, respectively.

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The formation constants of the adducts of 4, 4, 4-trifluoro-1-(2-thienyl)-1, 3-butanedionatolanthanoids(III) with 2-, 3-, and 4- phenylpyridines as well as the distribution constants and pK_a of these pyridines were determined on the basis of data obtained by solvent extraction from a 0.1mol/dm³ sodium perchlorate solution into chloroform containing TTA and/or pyridines. It has been found that the adduct formation constants(β) of a given lanthanoid(III) chelate increase along with increased pK_a of the phenylpyridine, and that the constants do not change much from light to middle lanthanoids, and then decrease for heavy ones. The constants for the 2-phenylpyridine adduct are lower than expected, possibly reflecting a steric effect. The pattern of a plot of log β₁ versus the atomic number is different from that with carboxylic acids and bidentate amines.

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Synergistic extraction constants for metal(II)-STTA(1, 1, 1-trifluoro-4-mercapto-4-(2-thienyl)-3-butene-2-one=HR)-nitrogeneous base(2, 2′-bipyridine=bpy, 1, 10-phenanthroline=phen) system were expressed by the HSAB parameters proposed previously. Stabilities of the synergistic adducts, ZnR₂(bpy), ZnR₂(phen), CdR₂(bpy) and CdR₂(phen), were also discussed by assuming the additive property of these parameters. The estimated stabilities were examined by ¹HNMR and IR measurements. The metal(II)-STTA bond was weakened by the coordination of additives. The formation of a ternary complex was considered to proceed through the reaction between a cationic complex and a chelate anion in the synergistic extraction system when a neutral bidentate nitrogeneous base such as phen or bpy was used.

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A chemically-modified Sephadex G10, on which a stearyl group and a quaternary ammonium base are introduced, was developed as a new adsorbent for carboxylic acids, and was applied to their separation analysis by using reversed-phase high-performance liquid chromatography (HPLC). Almost all carboxylic acids were quantitatively adsorbed on the chemically-modified Sephadex G10 at pH 8 without any interference from other inorganic ions included in environmental samples. Elution of the adsorbed carboxylic acids from the chemically-modified Sephadex G10 was easily accomplished using a dilute hydrochloric acid solution. A separation analysis by reversed-phase HPLC for preconcentrated carboxylic acids in environmental water was attained using an in-line color reaction for the carboxylic acids. The determination limits were 10^-7M for a 100ml sample volume. The relative standard deviations were less than 2%.

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Determination of amino acids in human plasma was performed by postcolumn ninhydrin derivatization liquid chromatography using a hydroxyapatite cartridge for precolumn deproteinization. This method was suitable for the determination of amino acids in human plasma. The proposed method was simple, rapid (deproteinization time: within 1min) and reproducible (relative standard deviation: ca. 0.4 to 5.4% (n=3)). Average recovery of 22 amino acids was over 80%. It took about 2h to elute the amino acids in human plasma on the chromatogram completely. Protein-binding tryptophan was also determined by the proposed method.

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By using a new chemiluminescent (CL) reaction system consisting of an urushiol/hydrogen peroxide/sodium hydroxide/ dye-sensitizer, a sensitive urushiol detection system was developed which featured a continuous flow method. The system comprises three-channel flow manifolds including an introduction manifold for the urushiol sample. The system has some advantages as regards instrumentation, sensitivity and analytical time; the detection limit is 1.O×10^-5M (S/N=2); the analytical time required is less than 30s for one sample feeding; the relative standard deviation is 6.2% for 5 repeated runs of the 1.0×10^-4M urushiol solution. A possible explanation for the CL reaction mechanism is also presented.

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A specific and sensitive radioimmunoassay (RIA) was developed for 4-[(5, 6, 7, 8-tetrahydro-5, 5, 8, 8-tetramethyl-2-naphthyl)carbamoyl]benzoic acid (Am-80), a benzoylamide derivative possessing retinoid activity, in dog plasma. Antisera were prepared by immunizing rabbits with Am-80 and its haptenic derivative conjugated with bovine serum albumin (BSA) and keyhole limpet hemocyanin. Their properties were investigated by heterologous combination using ¹²⁵I-labeled tracer. The antisera raised against BSA conjugate showed poor titers and high specificity, while the antisera from the other two conjugates showed high titers and reasonable specificity. The limit of quantification was 0.6ng/ml, when only 0.005ml of dog plasma sample was used per assay tube. The within- and between-assay variances were 1.2- 15.0% and 4.0-14.1 %, respectively. The direct RIA established here was highly specific for the determination of the unchanged form of Am-80 in dog plasma, enabling measurement of many samples at the same time.

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We describe an improved determination of conjugated bile acids hydroxylated at 1β-, 2β-, 4β- or 6α-position in urine sample of newborn by high-performance liquid chromatography employing labeling with 1-anthroyl cyanide and fluorescence detection. After extraction of bile acids from urine with a Bond Elut C18 cartridge, conjugated bile acids were separated into the three types of conjugates by ion-exchange chromatography on a lipophilic gel, piperidinohydroxypropyl Sephadex LH-20. The sulfated bile acids were solvolyzed by treatment with trifluoroethanol in acetone containing hydrochloric acid, followed by fractionation into the modes of conjugation with amino acids. The individual conjugated bile acids were labeled with 1-anthroyl cyanide in acetonitrile and triethylenediamine, and then separated on a C18 reversed phase column of high-performance liquid chromatography. The developed method showed the lowest limit of detection at 0.1pmol for the individual bile acids. It was available for the simultaneous analysis of double conjugated bile acids in urine of newborns.

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The fluorescence characteristics of various methoxycoumarin fluorophores for the development of fluorescence reagents were examined in relation to their structures. The fluorescence emission mechanisms were also considered from the viewpoint of the intramolecular charge-transfer (CT) between methoxyl substituents and the coumarin ring. The arrangement of 6-methoxyl and 3-acetyl group pairs on the coumarin ring significantly contributed to the fluorescence enhancement through the intramolecular CT. We found that the structural features of methoxycoumarins required for intense fluorescence are to hold both diether bonds at the 6- and 7-positions and an electron-withdrawing group at the 3-position, as shown in 3-acetyl-6, 7-dimethoxycoumarin with 0.52 in quantum yield.

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A precolumn fluorescence derivatization reagent for carboxylic acids, 2-(5-hydrazinocarbonyl-2-furyl)-5, 6-dimethoxybenzothiazole, was developed and its applicability to fatty acids in biological samples was examined. This reagent was proved to be useful in the determination of fatty acids in high-performance liquid chromatography with the detection limit of approximately 50fmol per 10-μl injection volume. Fatty acids in human serum were assayed by the derivatization method using the reagent. The method was also applied to some prostaglandins.

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In the extractive purification of commercial glycyrrhizin (about 90% in purity) with dual-flow countercurrent extraction, the extractive recovery of an impurity in the sample was wrongly estimated by a reported calculation method. To investigate the cause, we simulated the extractive separation of the impurity from glycyrrhizin by dual-flow countercurrent extraction. If one used the reported calculation method, the extraction recoveries of the impurity into the organic phase were calculated as 40.6% or as 99.3%, on two different assumptions: (1) the distribution ratio of the impurity changed depending on its concentration, or (2) it varied with the concentration of glycyrrhizin in the extraction apparatus. The experimental results (99.1% recovery of the impurity in the organic phase) agreed with the calculation based on the latter assumption. With the calculation method, the distribution map of the components in the extraction column could be shown as well.

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Methods for trace analysis of the 5f actinide elements are reviewed. Emphasis is on the non-radioactive methods of analysis such as absorption and laser induced spectroscopies, precipitation and/or sorption, ion exchange and solvent extraction. Particular attention is given to methods which allow measurement of the relative concentrations of the different oxidation states of a cation such as plutonium as they occur in nature. Comparisons are given of the sensitivities of these methods with that of traditional radioactivity counting.

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The carrier-mediated transport of gold(III), platinum(IV) and palladium(II) through a supported liquid membrane (SLM) has been investigated by the use of trioctylamine (TOA) as a mobile carrier. The transport behavior of precious metals greatly depended on the carrier concentration. At a low TOA concentration, Au(III) was preferentially transported across an SLM from the HCl feed solution to the HClO₄ product solution. The transport of Pt(IV) and Pd(II) was enhanced with increasing carrier concentration. The separation factor of Au(III) over Pt(IV) and Pd(II) was improved with increasing concentration of HCl in the feed solution.

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A sensitive spectrophotometric method for the determination of ultra-trace amounts of phosphate ion is proposed. The colored ion associate formed between molybdophosphate and Malachite Green (MG) was filtered through a tiny membrane filter (cellulose nitrate; poresize, 1.0μm; 9mm diameter), dissolved together with the membrane filter in 1cm³ or less of Methyl Cellosolve; the absorbance of the solution was then measured at 627nm with a flow-through system equipped with an autosampler. The absorbance, the standard deviation and the relative standard deviation of the reagent blank were 0.0270, 0.0005 and 1.8%, respectively. A calibration graph was linear over the range from 0.018 to 1.0ng cm^-3 (1ppb) of phosphorus using 40cm³ of sample solutions; the detection limit corresponding to two-times the standard deviation of the reagent blank was 3ppt of phosphorus. By using the proposed method, phosphate ion in pure water samples were determined.

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A simultaneous measurement system was developed for both an adsorbed substance onto a glass-slab optical waveguide surface and a dissolved substance in a flow cell by visible absorption spectrometry. The adsorption behavior of a blue dye of Methylene Blue onto an SOWG surface was kinetically studied by the present method.

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etal ions in solid and liquid materials can be extracted by supercritical CO₂ containing a suitable ligand. Bis(trifluoroethyl)dithiocarbamate is an effective ligand for the extraction of transition metals and non-metals in supercritical CO₂. Fluorinated β-diketones and tributyl phosphate in supercritical CO₂ exhibit a positive synergistic extraction for the lanthanides and actinides from solid and liquid samples. Triazole containing crown ethers can also be used for selective extraction of heavy metals in supercritical CO₂.

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A horseradish peroxidase (HRP)-catalyzed luminol chemiluminescence (CL) reaction was applied to the detection of hydrogen peroxide (H₂O₂) formed during the Cu(II)-catalyzed oxidation of amino thiol with oxygen. Cysteamine, L-cysteine, L-cysteine methyl ester and L-cysteine ethyl ester were used as amino thiols. A CL flash suddenly appeared after a certain dark period from the start of the reaction in all thiols used. The appearance of the delayed CL could be explained in terms of quenching function of the thiol for luminol radical formed through the enzymatic cycle of HRP. The quenching rate of luminol radicals with the cysteine esters was remarkably higher than those with cysteamine and cysteine.

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Some photophysical data including emission lifetimes (τ), total emission quantum yields (Φ), and ligand phosphorescence data are reported for the energy-transfer luminescence of the Eu(III) chelate of Quin 2 and the Tb(III) chelate of BAPTA: Quin 2 means 2-[(2-amino-5-methylphenoxy)methyl]-6-methoxy-8-aminoquinoline-N, N, N′, N′-tetraacetic acid; BAPTA means 1, 2-bis(2-aminophenoxy)ethane-N, N, N′, N′-tetraacetic acid. The energy diagrams for the ligand T₁ and the metal-center f-f levels are proposed. The τ values of Tb(III)-BAPTA chelates are 1.73ms in H₂O and 3.44ms in D₂O. The Eu(III)-Quin 2 chelate system shows a bi-exponential decay of emission; τ=0.048 and 0.20ms in H₂O and 0.066 and 1.44ms in D₂O. The Quin 2 chelate is kinetically inert, so that the interchange of these two conformer structures are very slow at room temperature. The number of water molecules in the primary coordination sphere is calculated from the lifetime data to be 1.9-2.4 for Eu-Quin 2 and 0.5 for Tb-BAPTA. The Φ values in aqueous solutions are rather small in these systems; 0.009 for Tb-BAPTA and 0.0023 for Eu-Quin 2, but these are enough counterbalanced by the large molar absorptivities giving the great sensitization factors for the ions; the sensitization factors against each aqua ion are 1380 for Eu-Quin 2 and 1600 for Tb-BAPTA.

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The advantages of fibrous materials filled with chelating sorbents for preconcentration purposes are discussed. These materials are suitable for the preparation of minicolumns used for on-line analysis. Minicolumns packed with fibers and chelating sorbents with amine, 8-hydroxyquinoline and 3(5)-methylpyrazole groups were used for the preconcentration of heavy metals and gold. The conditions of preconcentration and elution were examined. Satisfactory results of metal determination using these minicolunms were demonstrated for the example of copper and gold determination by the ICP AES method. The coefficient of concentration was 22; the limit of detection was 1μg/l.

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The use of aqueous or aqueous methanolic ionene (cationic polyelectrolytes consisting of dimethylammonium charge centers interconnected by alternating alkyl chain segments containing x and y methylene groups) solutions as mobile phases in thin layer chromatography (TLC) is described. The ortho, meta and para isomers of chlorobenzoic acid and phenylphenol as well as dinitroanilines and 1- and 2-naphthol were successfully chromatographed using aqueous solutions of [3, 16]-ionene with polyamide thin layer sheets. Some quinones were successfully resolved using this same aqueous ionene mobile phase but with cellulose thin layer plates. For some analytes, the TLC retention results obtained with the [3, 16]-ionene were compared to that obtained with [3, 6]-ionene, which does not form intramolecular aggregated species. The relevant properties of micelle-mimetic intramolecular ionene aggregates are described as are their possible advantages over conventional normal surfactant micelle systems. A brief prospectus on the future use of such micelle-mimetic ionene aggregates in separation science is presented.

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