A new extracting agent, 1-(4-ethylphenyl)-3-hydroxy-4-pyridone (C2-HPP), was synthesized and used for the extraction of aluminum(III), gallium(III) and indium(III) into 1, 2-dichloroethane. The acid dissociation constants, K_a, and the partition coefficient, K_D, of C2-HPP and the extraction constants, K_ex, of its metal complexes were determined. These results obtained were compared with those of 1-(4-ethylphenyl)-3-hydroxy-2-methyl-4-pyridone (C2-HMPP) reported already. The removal of a methyl group from the molecule of C2-HMPP was very effective for increasing the K_a values of C2-HPP and K_ex values of the metal complexes. The extracted species were ML₃ in all the extraction systems, where M denotes the metal ion.

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Continuous monitoring of the atmospheric concentration of methane (CH₄) has been carried out since August, 1990, in Nagoya, which is one of the typical urban areas of Japan. The atmospheric CH₄ concentration in Nagoya has shown some characteristic seasonal oscillations and daily changes; the CH₄ concentration was generally lower in the summer and higher in the winter; it was also relatively lower during the day and higher during the night. The annual mean concentration was 1.94ppmv in 1991, 1.93ppmv in 1992 and 1.98ppmv in 1993. These values are higher than the global average (1.72ppmv) reported by IPCC (1990), or the average in the northern hemisphere. The annual rate of increase for the last three years (from January, 1991, to December, 1993) was 2.78×10^-2ppmv/year, which corresponds to 1.4%/year. This rate of increase is also larger than that given in the IPCC report (0.9%) in 1990. These results suggest that there are some possible emission sources of CH₄ in the urban area of Nagoya. Furthermore, structural changes of the urban atmosphere should be taken into consideration when explaining the daily changes as well as the seasonal oscillation of methane.

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The present paper is a preliminary report concerning a continuous monitoring experiment for the atmospheric carbon dioxide (CO₂) concentration conducted since November, 1990, in Nagoya. Even though Nagoya is an urban area, the annual variation of the atmospheric CO₂ concentration shows a seasonal oscillation (lower in the summer and higher in the winter), as observed in the global atmosphere. In addition to the seasonal oscillation, a daily change in which the atmospheric CO₂ concentration was lower during the day and higher during the night was also observed. Furthermore, additional peak concentrations, which might arise from the exhaust gases of automobiles, were observed during the morning and evening rush hours. The annual mean CO₂ concentration was 381ppmv in 1991, 382ppmv in 1992 and 377ppmv in 1993. These values were significantly higher than those of the global mean concentration (353ppmv) in 1990. The annual rate of increase for three years (from January, 1991, to December, 1993) was -1.29ppmv/year, which corresponds to -0.34%/year.

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A new indirect method for the determination of iodide at the 10^-7mol l^-1 level based on the reaction of distilled I₂ with As(III) followed by the determination of the excess As(III) with hydride generation AAS is proposed. Iodide is oxidized to iodine by Ce(IV), distilled with a nitrogen carrier gas and absorbed in a KI solution. Absorbed iodine reacts quantitatively with excess As(III) in a slightly alkaline solution at 80-90°C. After the reaction iodide in the solution is removed as an AgI precipitate. The amount of distilled iodine can be determined indirectly by measuring the atomic absorbance of As by a hydride-generation technique. The calibration curve is linear over the range from 2.5×10^-8 mol l^-1 to 2×10^-7mol l^-1, and the relative standard deviation is 2.9% (n=7) for 1×10^-7mol l^-1 iodide.

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Multi-element determination of trace elements in seawater by inductively coupled plasma mass spectrometry (ICP-MS) has been investigated. Coprecipitation with gallium hydroxide was used for preconcentration of trace elements and elimination of matrix elements. Most trace elements were quantitatively collected at pH 10 with the concentration factor of 10. In the present experimental method, 17 elements (Al, Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Y, Zr, Sn, La, Pb, Th, U) in a coastal seawater sample could be determined by ICP-MS. In addition, 6 elements (Al, Mn, Fe, Ni, Cu, Zn) among them were determined by inductively coupled plasma atomic emission spectrometry (ICP-AES). The analytical results obtained by ICP-MS and ICP-AES were in fair agreement.

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The authors have developed an analytical method for determining trace amounts of 266 kinds of chemicals, such as pesticides, in natural water samples by GC-ion trap MS. The advantage of the method is not only that one can perform simultaneous determinations of a large number of chemicals within a short time, but also that experiments can be performed with high precision and accuracy, because the method has some quality-control systems. One liter of water was extracted by dichloromethane; the extract was concentrated to 1ml with a Kuderna-Danish concentrator. After adding internal standards, a qualitative and quantitative analysis by GC-ion trap MS was performed. The results concerning the overall recovery tests at 0.1μg/l showed that the mean recovery was 92.1% and that the mean relative standard deviation was 10.8%. The mean detection limit of the method was 0.036μg/l. To confirm the performance of the method, seawater and river water samples were analyzed. More than 100 chemicals were detected in water at below the 0.1μg/l level. This method is useful for elucidating the concentration levels and the fate of chemicals in the aquatic environment.

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Free fatty acids (FFAs) were determined by supercritical-fluid chromatography (SFC) on an inert ODS silica-gel column using carbon dioxide as a mobile phase without a modifier. The standard samples of FFAs with carbon numbers of 6 to 26 (even numbers) were completely separated using the pressure-programming mode. The retention behavior of FFAs was investigated in terms of the density of the mobile phase, and the FFAs were separated according to a reversed-phase mode in liquid-chromatographic terms. The composition of fatty acids of coconut oil was determined by the SFC, and was compared with gas chromatography. A good agreement was obtained. The chromatographic separation of FFAs obtained from fish oil as well as the enzymatic hydrolysis products of the fish oil were also conducted.

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A probability theory is presented to judge the utility of the internal standard method in high-performance liquid chromatography (HPLC). The relative standard deviation (RSD) of experimental results in the internal standard method is theoretically predicted based on the recently proposed uncertainty theory for sample dilution and HPLC measurement. The experiments comprise the taking of sample solution, addition of internal standard, dilution, measurement on HPLC and signal processing. Two kinds of correlation between concentrations of analyte and internal standard are formulated distinctively in the sample preparation process and in the HPLC measurement. The RSD values for the total experimental process are calculated from the volume error of pipette, signal shape of analytes and some probabilistic properties of baseline drift in chromatograms and are shown to be in good agreement with the observed ones over a wide range of dilution degree. The external calibration is also examined.

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A computer-controlled time-based variable-volume injector has been developed for the introduction of samples into a flow injection analysis system. Samples with a volume in the range of 8μl to a few milliliters can be delivered reproducibly (usually RSD<1.0%). Usefulness of the device is demonstrated by these applications: (1) the visualization of the relationship between the detector responses and the sample volumes injected which are fixed by specifying the injection time with a computer at an appropriate carrier flow-rate, and (2) the construction of a family of calibration plots.

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An electrochemical method has been developed for the determination of L-ascorbic acid (AsA) by a flow injection analysis. The method is based on a reaction of AsA with copper(II) at pH 5.0 to form a readily oxidizable species, followed by electrochemical detection at an applied potential of +20mV vs. Ag/AgCl. Under the optimum conditions a linear calibration curve was obtained for AsA over the concentration range from 0.1 to 20μM with a sample volume of 20μl. The relative standard deviation of the peak height for 10μM AsA was 1.0% (n=10). The method was successfully applied to the determination of AsA in fresh fruit juices and soft drinks. The obtained results are in good agreement with those obtained by high-performance liquid chromatography (r=0.994).

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A time-resolved Immunofluorometric assay (TR-IFMA) for interferon-γ (IFN-γ) was developed and its properties were compared with those of previously reported immunoenzymometric assays (IEMAs). The advantage of TR-IFMA is not only that it is as sensitive as the usual colorimetric IFMA, but that it is also feasible and fast as a detection procedure of europium. It was modified in order to make it more sensitive and faster by changing the antiserum and incubation conditions. The improved assay could directly measure IFN-γ in human plasma without any pretreatment. The detection limit for IFN-γ is 40pg/ml, and an assay can be completed within 6 h.

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A new chemiluminescence method is described for the determination of 6-mercaptopurine. In the presence of tris(2, 2′-bipyridine)ruthenium(II), 6-mercaptopurine (6MP) and hydrogen peroxide, upon the addition of hydroxide ion, resulted in intense light emission. The emission intensity is greatly enhanced by the presence of Tween-20. The linear range and detection limit of 6MP are 1.4×10^-5-1.4×10^-8g/ml and 3×10^-10g/ml, respectively. The method was evaluated by carrying out an interference study with common excipients and other coexisting compounds, by a recovery study and by the analysis of commercial formulation. A satisfactory result was obtained.

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The formation constants for 1:1 complexes between Li⁺ or Na⁺ and a monocyclic polyetherdiamine, cryptand[2.2], were evaluated in acetonitrile at 25±0.2°C by three d.c. polarographic analyses: the positive shift in E_1/2 of the anodic (mercury dissolution) wave induced from cryptand[2.2] in the presence of a large excess of LiClO₄ and NaClO₄; the positive shift in E_1/2 of the cathodic wave of the [HgL]²⁺ complex (L=cryptand[2.2]) in the presence of a large excess of alkali metal ions; and the negative shift of the cathodic wave of Li⁺or Na⁺ in the presence of a large excess of cryptand[2.2]. The above three analyses gave complex formation constants that were consistent with each other within experimental error. In a less solvating medium (benzonitrile), stronger interactions were observed between the cations and cryptand[2.2]. The interaction between alkali metal ions and 1, 10-diaza-4, 7, 13, 16-tetrathiacyclooctadecane (ATCO) was very small, even in benzonitrile. The complex formation constants of [SrL′]²⁺ and [BaL′]²⁺ (L′=ATCO) in acetonitrile were both ca.10^2.5 by the first two methods mentioned above.

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Theoretical approaches to aluminum-ion determination by two potentiometric methods (potentiometric titration and analyte subtraction potentiometry) are discussed. The computed theoretical titration curves show that the equivalence point is signaled by a sufficiently large change in the potential only in media where aluminum forms a hexafluoride complex; the overall formation constant of this complex is β(AlF₆^3-)≥10²⁸. On the basis of the potentiometric titration and the known subtraction experiments in 2-propanol-water, buffered with acetate buffer (pH 5), the overall conditional constants (β′) were calculated. The calculated average β′-values are 10³¹ and 10³³, depending on the vol% of organic solvent, 50% and 67%. In the mixtures having a vol% of organic solvent of 50% or 67%, both methods can be applied for the determination of aluminum, via AlF₆^3- complex formation, in the concentration range from 10^-4 to 10^-3M.

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The optimal conditions for the development of complexation reactions between Cr(III) and 2-(5-chloro-2-pyridylazo)-5-dimethylaminophenol (5.CIDMPAP) were studied. When a mixture of a hydroethanolic solution of the reagent and an aqueous solution of Cr(III) were heated, three different complex species were formed, depending on the composition and pH of the medium (ε=1.7×10⁵l mol-1 cm^-1). All of them were hardly soluble when the proportion of organic solvent was low. The stoichiometry of the different complexes was determined, the formation mechanisms were elucidated and the respective constants were calculated. A useful absorptiometric method is proposed for Cr(III) in concentrations ranging from 15 to 400ppb. The proper ways to reduce interferences produced by Fe(III), Nb(V), Ta(V), Ti(IV), V(V), Co(II), Zr(IV), Sn(II), Al(III), Mn(II) and Cu(II) are described. The methods were applied to chromium determination in water samples with very satisfactory results.

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The historical development of the basic physical concepts of total reflection, anomalous surface-reflection (ASR) and other grazing incidence phenomena are reviewed with respect to their impact on the development of TXRF as an analytical method in the introduction. The physical principles and technical arrangements for a broad field of actual applications are described. These major applications (total reflection sample support, total reflection cut-off filter, total reflection trace element and microanalysis, glancing incidence X-ray analysis (GIXA: surface and thin layer analysis), glancing incidence X-ray diffractometry) are described. The recent developments of research related to improving the detection limits of TXRF and trends to improve its scope and analytical power are described with respect to their potentials for further progress.

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TXRF with a special energy dispersive spectrometer is well suited for analyzing light elements, such as C, N, O, F, Na, Mg and Al. The elemental sensitivity is mainly influenced by the energy of the exciting radiation. Different excitation energies from 1.7 to 17.5keV and the resulting background due to scattering on the reflector substrate under total reflection conditions were studied theoretically. The angular dependence of the fluorescence signal from low-Z atoms implanted in Si, excited by monoenergetic radiation of various energies, was calculated. The same was also done for Ti atoms implanted in Si, and compared with the measured results. The excitation energy in the experiments was monochromatized Cr-Kα radiation. In addition, results obtained with synchrotron radiation as the excitation source are presented. A detection limit of 200fg for Mg has been obtained.

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Fibers of different textile materials, such as polyesters, viscose, and wool, were analyzed using TXRF, yielding a "fingerprint-type" trace element pattern. This pattern can be compared with quantitative results obtained from weighable amounts, e.g. 50μg of the material. It can be shown that, besides the omnipresent elements Ca, Fe and Zn, some of these materials contain specific elements, such as P, Mn or Sb, and that an identification is possible using these elements even when very small amounts of sample are involved (i.e. sub-microgram). Since many synthetics contain Ti as a matting additive, the Ti concentration can be used to further differentiate the sample material.

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A glazing incidence X-ray fluorescence analysis (GIXF) has been applied to forensic samples: a counterfeit 100-dollar bill, fragments of polyvinyl tapes, a trace of semen, illegal drugs, fingerprints and fake V.S.O.P brandy. Strontium could not be detected on the magnet-respondent letter of the counterfeit bill and Br was detected on the magnet-nonrespondent part of the counterfeit bill, while such phenomena could not be noticed on a true bill. Fragments of black vinyl tapes related to a sexual assault case could be discriminated from each other. Zinc as a characteristic ingredient could be detected in a trace of semen. Bromine was detected in each of what is called a pure methamphetamine crystal and K, Ca, Fe, Zn etc. were detected in heroin powders. Lead was sharply detected in gunshot residues attached to a finger after gun-firing. Sulfur as a contaminant was abundant in fake V.S.O.P brandy, while no S was detected in genuine V.S.O.P brandy.

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The collection of airborne particulate matter by filtration and impaction was adapted to total reflection X-ray fluorescence analysis (TXRF). Cellulose nitrate filters were used for collecting in a Berner impactor. Single filter spots were punched out, placed on quartz-glass carriers, dissolved by tetrahydrofuran and re-precipitated prior to element determinations by TXRF. In a Battelle-type impactor, airborne dust was collected on Plexiglass^®carriers coated with medical Vaseline^®. The loaded carriers were directly analyzed by TXRF. In both cases, quantification was simply performed by the addition of an internal standard after sampling. Impactors were made of a suitable material in order to investigate high blank values, collection losses and memory effects. It could be shown that stainless steel, even coated with TiN, is less suitable and should be avoided as an impactor material. Although aluminum is partly recommendable, titanium and the polymer Makrolon^® are quite appropriate. By using an impactor made of these materials, a reliable multielement determination in airborne dust is made possible with low detection limits as low as 1ng/m3 and a satisfactory repeatability of a few %. Short sampling times of only 1h or less can be realized. The total procedure is simple and time-saving, and can be recommended for routine investigations of airborne particulate matter.

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Total reflection X-ray fluorescence spectrometry (TXRF) is widely used for the determination of surface metal contamination on a silicon wafer. In TXRF measurements, calibration standard samples are needed to quantify the metal concentration. We propose a new method for the preparation of calibration standard samples for TXRF. The method is called "Immersion in Alkaline Hydrogen Peroxide Solution (IAP)", in which the silicon wafers are immersed in an intentionally contaminated alkaline hydrogen peroxide solution. Samples made by the IAP method are suitable calibration standard samples for TXRF because of their good depth profile reproducibility and good uniformity on the surface as well as homogeneity in a given batch. They can also be applied for making a cross-check among plural TXRF instruments as well as among different analytical methods.

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This paper presents details concerning such spurious peaks as Fe Kα and Ni Kα radiation, which are often observed in the trace determination of metallic impurities on silicon wafers by using a monochromatic total reflection X-ray fluorescence (TXRF) analyzer. The intensity of a spurious peak varies along with changes in the incident azimuth angle and/or detected intensity of the primary X-ray beam. The origin of this phenomenon is impurities existing along the path of X-rays. This phenomenon influences the accuracy of trace TXRF analysis, and a practical detection limit of a TXRF analyzer becomes worse by approximately one order, becoming 10¹¹atoms/cm², than the calculated detection limit (2-8×10¹⁰atoms/cm²) in our case.

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Total reflection X-ray fluorescence (TXRF) and vapor phase decomposition (VPD) followed by TXRF have become widespread methods for measuring surface metal contamination on silicon wafers. For quantification, TXRF and VPD/TXRF require reference samples. Since the approaches to making and using these reference samples have significantly varied among TXRF manufacturers and users worldwide, there exists some confusion about the quantification of TXRF and VPD/TXRF. This paper summarizes the basic issues behind TXRF and VPD/TXRF quantification using reference samples.

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We explored total reflection X-ray fluorescence spectroscopy (TXRF) with a synchrotron source to achieve high sensitivities to surface metals on silicon wafers. Most recently, we directly demonstrated a sensitivity of 3×10⁸atoms/cm² for third-row transition metal elements. The configuration appears to be capable of high sensitivities for a wide range of elements.

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X-Ray absorption and X-ray photoelectron spectroscopic measurements of specular surfaces using grazing incidence soft X-rays carried out by the present authors are summarized. The merits of using a sample current induced by totally reflected X-rays are discussed. The probing depth of the sample current has been found to be restricted to within a very shallow surface. The application of the sample current X-ray absorption experiment to the depth profile analysis of fly-ash powders is described. Very clear X-ray photoelectron spectra excited by totally reflected X-rays are for the first time reported.

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A new method has been developed for investigating the geometrical structure of chemical species present at a solution surface. The method is the X-ray absorption fine structure (XAFS) spectroscopy which is combined with X-ray introduction under a total reflection condition. It was applied to aqueous solutions of bromide and rubidium ions with and without surface-active counter ions. The solvation structure for Br^- segregated at the surface by surface-active cation has been found to be different from that in the bulk. The coordination numbers for both the cation and anion at the surface have also been found to be different from those in the bulk. Due to the highly polarized X-ray radiation from a synchrotron used in this study, the coordination number determined by this technique must reflect the preferential orientation of the observing atom-atom bond with respect to the solution surface. Thus, the solvation structures and orientations for ions at the surface are discussed.

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The use of X-ray fluorescence and reflectivity techniques for the characterization of the layer structures of multiple-layer thin films is described. The X-ray fluorescence technique is used for the precision determination of composition and layer thicknesses of two triple-layer NiFe, Cu, and Cr thin films. The X-ray reflectivity technique is used to determine the values of layer thickness, density, and roughness of a six-layer Ta/FeMn/NiFe/Cu/NiFe/Ta thin film. Both X-ray fluorescence and reflectivity techniques are used for the analysis of two Au/NiFe multilayers. The results showed that the X-ray fluorescence and reflectivity techniques are complimentary. The use of both techniques for layer-structure determinations improves the reliability of the analysis.

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Only three types of specimens can be applied for calibration in TXRF, namely pure particle-, film- or bulk-type samples. In this study "droplet" standards, as a representative of the particle type, and "spin-drying" standards, for film-type samples were examined and compared with a pure metal standard (bulk-type). A test procedure is described which makes it possible to detect faulty calibration samples. An iterative data processing technique is presented which extracts layer characteristics and-to a certain extent-depth profiles from TXRF data as a function of the incident angle. Two selected examples are considered, a Fe-Ti-Fe thin-layer system and an implantation profile of Ni-atoms in silicon. Based on these samples, the capability and limitations of TXRF for depth profiling are discussed.

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By detecting characteristic X-rays excited during a RHEED (reflection high energy electron diffraction) experiment, a highly sensitive measurement of the adsorbate is possible if the X-ray detector is placed at the critical angle (θ_c) corresponding to the total reflection of the X-rays. Furthermore, by measuring the glancing angle (θ_g) dependence, it is possible to analyze the depth distribution of the composition at the surface. The resolution in the depth direction is about 1ML. By applying these methods to studying the epitaxy of metals (Ag, Au, Sn, Ga and In) on Si(111)-n×m-M surface structures (metal-induced Si(111) reconstructed surface structures), new growth modes were observed, such as the substitution-atom growth mode, the floating-atom growth mode and some complex growth modes.

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We have measured the vertical distribution of a radioactively labeled protein in an aqueous solution by using the interference effect of electron-capture X-rays from radioisotopes. This interference is between the direct monochromatic emission from radioactive atoms and the emission totally reflected by the substrate surface. Structural information about radioactive atoms can be obtained by analyzing the measured interference fringes, since the period of these fringes depends on the position of the radioactive atoms relative to the substrate surface. In this work we used bovine serum albumin radioiodinated with carrier free ¹²⁵I by using Chloramine T. The protein molecules were electrostatically adsorbed in a monolayer form by the positively charged Langmuir layer at the air-water interface.

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The fluorescence intensities in grazing-emission X-ray fluorescence spectrometry were calculated by applying asymptotics to the Fourier integrals resulting from the Helmholtz equation. This approach has led to a straightforward interpretation of the interference of fluorescence radiation from layered materials. A good agreement between the calculated and experimental fluorescence intensities has been shown.

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