Waveguiding in a sample solution and total reflection for absorption and fluorescence (Raman) spectrometries are reviewed. Wave guiding in liquid or air (or solid) via successive total reflections at the surface of media is an important technique to improve the sensitivity of spectrometry, which is generally seen in optical fiber. When applying a liquid (or solid) of higher refractive index to a capillary, the source light passes through the capillary without attenuation (total reflection). In this case, the absorption of liquid enhances more than elongation of the length of the capillary. A waveguiding effect is applied not only in absorption spectrometry, but also in fluorescence and Raman spectrometry. A sulab-type waveguide geometry is also employed as total-reflection cells of various spectrometries. Evanescent waves during total reflection are utilized to observe the local environment at the point of reflection. Applications of optical fibers are also briefly mentioned in this review.

View full abstract

This paper describes highly sensitive and selective catalytic-spectrophotometric methods for the determination of metal ions such as copper(II), cobalt(II), chromium(III), iron (II, III), manganese (II) and vanadium (IV, V). These methods are based on their catalytic effects on the following color-forming reactions: (1) the hydrogen peroxide oxidative coupling of N-phenyl- p-phenylenediamine (PPDA) with N, N-dimethylaniline (DMA) or m-phenylenediamine ; (2) the oxidation of PPDA with hydrogen peroxide ; (3) the oxidative coupling of 3-methyl-2-benzothiazolone hydrazone with DMA or N-ethyl-N-(2-hydroxy-3-sulfopropyl1)-3, 5-dimethoxyaniline in the presence of hydrogen peroxide or dissolved oxygen ; and (4) the bromate oxidative coupling of 4-aminoantipyrine with DMA. In order to enhance the catalytic effect of metal ions and improve the sensitivity of the methods, some ligands were used as activators. Furthermore, the addition of surfactants to the reaction systems also increased the sensitivity. The present photometric methods with a batch and/or flow-injection mode allow for the determination of the metal ions in the range 10^-1110^-7 M with good precision. These methods have been successfully applied to the determination of these ions in real samples.

View full abstract

We have developed video-microscopes to analyze the dynamics of micro organs in living cells and to clarify the secretory mechanisms of granules which contain hormones and transmitters in living cells. Rat basophilic leukemia cells, which exhibit a Ca²⁺-dependent secretion of granules, were observed using a video-enhanced light/fluorescence microscope. Simultaneous analyses of the membrane potential and calcium mobilization in a pancreatic β cell line MIN6 using a double-probe imaging microscope system was useful for analyzing the cellular mechanism of insulin secretion. The ciliary movement of tracheal epitheliums was also analyzed using an advanced video-microscope with pulse-flow injection. A chromate-video scope was a novel direct detection system of the sample distribution on the column. It was applied to analyze the dynamic movement of the solute's band. A direct observation of the on-column movement in the stepwise elution mode made it possible to evaluate a void volume of the column. The distribution of solutes in the inner surface reversed phase column was also observed.

View full abstract

In flow-injection analysis (FIA), useful on-line treatments or systems can be incorporated. On-line treatments, such as heating, extraction, separation by gas diffusion and reduction or oxidation with a packed column, were utilized for FIA. Heating is a simple method to accelerate the reaction rate; it was applied to the reduction of molybdophosphate to molybdenum blue, and the formation of a complex of boric acid and H-resorcinol. The pyrolysis of condensed phosphate and organic phosphate to orthophosphate with potassium peroxodisulfate was accomplished by heating the PTFE tubing at 150°C. In this case, heating was carried out by winding a PTFE tubing on an aluminum heating block. The separation procedure was carried out with extraction or gas diffusion through a hydrophobic membrane or a porous membrane. Segmenters and phase separators for extraction/FIA were newly designed and applied to the determination of phosphorus, anionic surfactants, potassium and calcium. Gas-diffusion units were newly designed with porous membrane tubing, without glue, and were applied to the determination of dissolved total carbonate and ammonia in environmental water samples. Oxidation and reduction by a photo-reactor or Cu/Cd-packed column were applied to hydroxylamine, nitrate and nitrite determinations. The photo-reactor (low-pressure mercury lamp) acted as both an oxidant and a reductant, and the oxidation rate of hydroxylamine was accelerated by winding a reaction tubing packed with TiO₂ adsorbing glass beads on the photo-reactor. To minimize the system for less consumption of the sample and chemicals and for on-site analysis, the flow system was modified with a micro pump propelled 0.25 μl stroke^-1, and a minimized Cu/Cd packed column was designed for this system. Glass beads with immobilized glucose oxidase were packed in PTFE tubing and glucose was determined by using oxidation/reduction between iodine and hydrogen peroxide.

View full abstract

The authors discuss here novel approaches to apply conducting polymers in analytical and separation chemistry. This paper describes (1) the fabrication of size selectivity and molecular-recognition property into the polymer for sensor applications, (2) ion-exchange chromatography controlled electrochemically under a fixed or modulated stationary phase potential, and (3) the physicochemical properties of soluble conducting polymer colloids, which can be utilized as novel separation and concentration media and as intelligent microcapsules. Functionality, such as an enantio discrimination property, was incorporated automatically into a conducting polymer through oxidative doping of an anionic compound upon polymerization. In order to provide more flexibility and to use the polymer in wider ranges of applications, the authors have developed soluble conducting polymers with ion-exchange capabilities, which can be controlled by the pH or the potential in solution.

View full abstract

The analytical performance of a long torch used in an ultrasonic nebulization system for axially viewed horizontal inductively coupled plasma atomic-emission spectrometry (ICP-AES) was examied using a high-resolution echell spectrometer with wavelength modulation and second-derivative detection. The optimum operating condition of the ICP-AES and the relative ratios of the delivery of the sample aerosol to the plasma torch of ultrasonic and cross-flow nebulization systems were studied for 21 elements having spectral lines between 210 and 770 nm. The relative ratios of the delivery of the sample aerosol were about 14% for the ultrasonic nebulizer and about 1% for a cross-flow nebulizer. In comparison with the conventional torch used in an ultrasonic nebulization system, net emission intensities of 21 elements increased by 2040%, and the background intensities of water and its fluctuation decreased for all elements. The values of S/σ (S, signal intensity of an analyte; σ, standard deviation of the background intensities) and BEC (background equivalent concentration) were improved for all elements. The limits of detection were improved by 1.2-fold (Ga) and 5.2-fold (K). On the other hand, in contrast to a long torch used for the cross-flow nebulization system, the net emission intensities increased by 8-fold and 15-fold in many elements, and the background intensities of water decreased due to the desolvation effect. The values of S/σ. for the greater part of the elements were improved by more than 10-fold and the BEC values were improved by 7-fold and 12-fold. The detection limits were improved by 3.3-fold (Zn) to 26-fold (Ag, Ba). In comparison with the conventional torch used for the ultrasonic nebulization system and the long torch used for the cross-flow nebulization system, the repeatability produced by the relative standard deviation of the net emission intensities was improved. The dynamic range for each element was about four or five orders of magnitude. The emission line (422.673 nm) of Ca showed interference by Na above 1 mg dm^-3 when using the long and conventional torch for ultrasonic nebulization system, and showed interference by Na greater than 50 mg dm^-3 using the long torch for cross flow nebulization systems; however, it was scarcely affected by phosphoric acid of below 3 v/v%. In order to demonstrate the usefulness of this work, the direct analysis of a standard reference material, NRCC SRM SLRM-2 (river water), was performed. Good accuracy and precision were obtained, except for a few elements.

View full abstract

In a Grimm-style glow discharge optical emission spectrometry, the emission characteristics of the spectral lines of all lanthanide elements, except for Pm, were investigated. The ionic resonance emission lines, which are commonly employed as analytical lines in ICP analysis, are also very intense in glow discharge emissions. In addition, atomic resonance lines having excitation energies of 2.53 eV can be predominantly excited by the glow discharge plasma, thus being available for the trace determination. These effects might be explained based on the difference in the excitation mechanisms between the glow discharge plasma and the ICP. The limit of determination obtained by glow discharge excitations, which was defined as the sample concentration corresponding to three-times the full fluctuation of the background intensities, was estimated to be 2.4 × 10^-4 atomic% for Eu I 459.402 nm, 1.6 × 10^-4 atomic% for Yb II 328.937 nm, and 6.1 × 10 ^-4 atomic% for Dy I 421.170 nm, for example.

View full abstract

Major-to-ultra trace elements in lake sediment reference materials from Lake Biwa (JLk1) and Lake Baikal (BIL-1) were determined by inductively coupled plasma atomic-emission spectrometry (ICP-AES) and inductively coupled plasma mass spectrometry (ICPMS). The sediment samples were decomposed by lithium metaborate (LiBO₂) fusion in a platinum crucible. Then, the decomposed sediment samples were dissolved in a 1 M HNO₃ solution, and subjected to the determination of the major, minor and trace elements by ICP-AES and ICP-MS. Furthermore, rare-earth elements were determined by ICP-MS after cation-exchange separation from the major and minor elements. Consequently, 43 elements in both sediment reference materials were successfully determined by the present analytical method. This method was also applied to a multi element analysis of 100 m sediment boring core samples (BDP 93-2) collected from Lake Baikal in 1993. The analytical data for sediment reference materials and the vertical distributions of Si, Fe, Ti, Ba, Zn, U and Lu in Lake Baikal sediment core samples are discussed from geochemical points of view.

View full abstract

A simple method has been investigated for the direct determination of copper in biological samples by graphite-furnace AAS with a slurry method. This method is based on the atomization of copper by introducing powdered-biological samples suspended in 1 mol l^-1 nitric acid as a dispersant. A biological sample (1 10 mg in weight) containing less than 0.50 μg of copper is placed in a polystyrene test tube (15 m1). Then, 5.0 ml of 1 mol l^-1 nitric acid is added to the tube, and the sample is dispersed into the solution by an ultrasonic agitator for 1 min, after which 10 μl of a homogeneous suspension is introduced into a graphite furnace. When the copper content is very small, the introduction of this slurry (10μl) is repeated less than 10 times until the drying and ashing step. The optimal heating programs are obtained as follows: drying at 160°C for 60 s, ashing at 600°C for 30 s, and atomization at 2600°C for 5 s in an argon atmosphere (flow rate, 2.0 l/min). The 324.8 nm line was used to determine copper in the peak-area method; also, a background correction was made by a deuterium lamp. Calibration can be performed with aqueous standards, because the standard solution containing 1mol l^-l nitric acid is responsible for the error in the determination value. The relative standard deviation was 3.4% for 6 measurements on 63.8 μg g^-1 copper in a SRM 1566a from the NIST.

View full abstract

A ferromagnetic alloy foil (Pyrofoil) has been used in a Curie-point pyrolyzer as a heating source for pyrolysis. However, it has been reported that the yield ratio of the pyrolyzates varied depending on the composition of the inorganic substances on the surface of the Pyrofoil. Therefore, this investigation was performed in order to enhance the reproducibility of the simultaneous pyrolysis and methylation pyrolysis (SPM) using four testing methods: (1) the use of a gold-plated Pyrofoil (G-F), (2) the use of a platinum plated Pyrofoil (Pt-F), (3) a double-wrapping method fa sample previously the wrapped in aluminum foil is wrapped over with the Pyrofoil (Al-F) and (4) use of nontreated Pyrofoil (N-F). Polybutylene terephthalate (PBT) was used as the standard sample. G-F showed the best RSD for the dimethyl terephthalate peak, less than 0.7 when measuring the relative peak ratios; further the order of the RSD was G-F < N-F < Pt-F < Al-F. Brief overviews of applications to the compositional analysis of another PBT (isophthalate : terephthalate = 15 : 85, PBi & t-T) and a liquid-crystalline aromatic polyester (Vectra) are also given.

View full abstract

Although ICP mass spectrometry offers a powerful multi element analytical method, the background spectra often interfere with the determination. The detectability for halogens is not adequate because of insufficient ionization. In the present work, a low-pressure helium ICP was studied in order to overcome these problems. A plasma was sustained with a water-cooled torch at 400 800 W forward power with a maximum signal intensity at 500 W. The optimal plasma gas-flow rate and sampling depth were 40 ml min^-1 and 17 mm, respectively. The signal intensities of ¹²⁷I⁺ were much higher than those of the conventional atmospheric-pressure Ar ICP. Background species (ArN⁺ and Ar₂⁺) were not observed, which may allow the determination of traces of Se (as ⁸⁰Se⁺) as well.

View full abstract

The use of p-nonylphenol as a coordinative and reductive extraction solvent was investigated. p-Nonylphenol floats on the surface of an aqueous solution as a semi-spherical droplet, and is useful for the extractive enrichment of metal ions. Cationic iron (II), cadmium (II) and copper(I) complexes with 1, 10-phenanthroline type ligands were quantitatively extracted into the p-nonylphenol phase without the presence of bulky counter anions, such as the perchlorate ion. Moreover, no reducing agent is necessary for the reductive extraction of iron(II)-1, 10-phenanthroline and copper(I)-neocuproin complexes from iron(III) and copper(II) solutions, respectively.

View full abstract