BUNSEKI KAGAKU Abstracts

Novel chelating reisns derivatized from organic synthetic polymers and a biopolymer, chitosan, have been reviewed with respect to the collection and separation of metal ions in aqueous samples for trace analysis. The adsorption behavior of metal ions on resins and their adsorption abilities have been elucidated in detail. Chelating reins have been widely used in the analytical fields, where pretreatment with chelating resins is a powerful technique, and is requsite for an accurate and reproducible determination of trace metals. In this review, the adsorption properties (adsorption conditions and adsorption capacities) of metal ions on the chelating resins are summarized in detail : as base materials, organic synthetic polymers and a biopolymer are used for developing derivatives with chelating moieties. Also, the applications of chelating resins to trace analysis for metals are described. A number of preconcentration techniques with a batch-wise column pretreatment and an on-line column pretreatment method reported for the analysis of trace metals are also reviewed.

In the time-resolved spectroscopy, physical or chemical responses of samples after the irradiation of a short optical pulse were measured, and physical and chemical properties of samples or dynamics of chemical reactions were analyzed. The transient grating method, one of the time-resolved methods, gives various types of information that is difficult to obtain by other methods, such as thermal and acoustic dynamics, dynamics of optically silent chemical intermediates. However, this method has a disadvantage concerning difficulties of optical setup and analysis of data ; also it is difficult to use by general researchers. Recently, we have developed the near-field heterodyne transient grating method, which is much improved from the conventional transient grating method concerning various points. The main features of this method are : 1. very simple optical setup ; 2. applicable for various sample states, such as solids, liquids, interfaces, and rough surfaces ; 3. wide dynamic range measurements from femtoseconds to seconds ; 4. selective detection of the real and imaginary parts of the refractive index changes. In this report, several application examples are shown, and the above-mentioned features of this method are explained.

Cheleteing resins based on wood powder with polyamine were prepared, and the characterization of adsorption for metal ions was studied. Cedar sawdust was treated with a hydrochloric acid concentration of about 100°C for 4 h. Next, the modified cedar sawdust was reacted with polyamine at about 100°C. When the cedar sawdust was treated by triethylenetetramine, the content of nitrogen contained in cedar sawdust was higher than after treating with other polyamines. Hg^2＋ and Cu^2＋ were adsorbed on cedar sawdust with polyamine compared to other metal ions. The pH range for the adsorption of Hg^2＋ and Cu^2＋ was about 3∼6. The maximum adsorption capacity was 0.3 meq Cu^2＋ g⁻¹ (dry resin). The rate of adsorption was rapid, and the adsorption equilibrium was attained within about 5 min. Thus, the cedar sawdust with polyamine could be used with a high flow rate to the column operation. When 20 L of tap water containing 0.01∼10 mg of Cu^2＋ and Hg^2＋ in the presence of several metal ions was developed by the column method, Cu^2＋ and Hg^2＋ could be recovered in about 100 w/w％.

A flow injection (FI) spectrophotometric method for the simultaneous determination of ascorbic acid (AA) and glutathione (GSH) in a single injection (one-shot) is presented. The method is based on the reaction kinetics of a reduction reaction of an iron(III)-1,10-phenanthroline (phen) complex to a red iron(II)-phen complex (λ_max＝510 nm) with each reducing compound. AA rapidly reduces an iron(III)-phen complex to a red complex, while the reaction rate with GSH is very slow. However, copper(II) greatly accelerates the reaction rate with GSH. Therefore, in the presence of copper(II) the concentration of the produced red complex corresponds to the total concentration of AA and GSH. A double flow cell that has two cell compartments in parallel is installed in a double-beam spectrophotometer. The use of the double flow cell makes it possible to detect simultaneously two analytes from a one-shot, i.e. AA can be detected at 510 nm in the absence of copper when an injected sample zone passes through the first compartment in the double flow cell, and then after the sample zone merges with a copper(II) solution, the total concentration of AA and GSH can be detected in the second compartment. Under the optimum conditions, AA and GSH can be determined simultaneously in the ranges of 5×10⁻⁷∼5×10⁻⁶ M for AA and of 2×10⁻⁶∼1×10⁻⁴ M for GSH with a sample throughput rate of 45 h⁻¹. The proposed FI method was successfully applied to the determination of these compounds in pharmaceutical preparations and a supplement.

Trimethylamine (TMA) is a compound with an unpleasant odor, like ammonia. We previously reported a detection system for trace TMA in ambient air by using a headspace gas-chromatography-surface ionization detector. In this study, a novel denuder sampler coated with titanium dioxide was developed. TMA, which was naturally contained in phosphoric acid used as a collecting solution, was photochemically decomposed by the denuder. Consequently, the denuder greatly reduced the TMA blank level. The detection limit of TMA was 0.004 ppbv for 60 L of an air sample. The analytical results of TMA in the lavatory showed good agreement with the values obtained by the bubbler sampling method.

A parallel beam X-ray diffraction analysis (XRD) machine equipped with a parabolic multilayer, Soller slit and long horizontal slit has been applied to tubular zeolite NaA (LTA) membranes supported by a porous alumina tube, prepared by hydrothermal synthesis for the dehydration of ethanol. The present XRD is a suitable method used to analyze tubular LTA membranes and give a sharp XRD pattern, because the sample form does not affect the diffraction angles. For lattice-constant measurements, six diffraction lines in the 2θ region of 40∼60° were used, and their diffraction angles were corrected using 220 and 311 lines of silicon powder (NIST SRM640c) as an external standard. The XRD measurements were carried out for LTA membranes after pervaporation experiments of an ethanol/water (90/10) mixture, and the observed lattice constants were 24.573∼24.599 Å, corresponding to the hydrothermal synthesis condition. Thus, the lattice constants of the tubular LTA membranes were first reported.

A rapid discrimination method of amino acid drinks (AADs) by microscopic Fourie-transform infrared spectroscopy (FT-IR) and electrospray ionization mass spectrometry (ESI-MS) was studied for forensic identification. The ten descriptions of PET bottle AADs (several tens μL) were used as samples. Types of saccharides contained mainly in the drinks were given by the FT-IR analysis. The results by the ESI-MS analysis of samples diluted twice with acetonitrile were as follows : amino acids and saccharides were mainly detected as [M＋H]^＋and [M＋Na(or K)]^＋, respectively, in the positive mode. Acidity regulators and saccharides were mainly detected as [M−H]⁻ and [M＋Cl]⁻, respectively, in the negative mode. The FT-IR and ESI-MS analyses used in this study rapidly discriminated all samples of the AADs, and could be applied to screening tests of the AADs.