We developed a flow-through chemical analyzer usable in seawater up to a depth of 2000m. The analyzer, which can measure silicate and hydrogen sulfide dissolved in seawater, consists of the following four parts: (i) an acrylic oil-filled vessel containing the flow-through analyzer, (ii) a pressure housing containing electronic circuits (CPU, data logger and drivers to control the analyzer), (iii) a bundle of plastic bags keeping analytical reagents and waste solutions and (iv) batteries for powder supply. Si and H₂S are determined colorimetrically using the Molybdenum Blue method and the Methylene Blue method, respectively. After the test operation up to a pressure of 2×10⁷ Pa in a shore-based laboratory, the system was submerged in seawater down to 1200m depth to perform successful in situ Si measurements.

抄録全体を表示

The two-photon ionization spectra (wavelength dependence of the photoionization charge) of the three title molecules have been measured on the water surface in the region of 340-440nm using a Ti-sapphire laser. The signal was quadratic to the laser pulse energy. The peaks in the observed spectra are closely correlated with those in the one-photon absorption spectra in solution. The detection limit depended on the wavelength used and was better at band peaks in the photoionization spectrum.

抄録全体を表示

The copper 2p X-ray photoelectron spectra (XPS) of cupric complexes, the structures of which have been well characterized, were measured. The intensity of the so-called "shake-up" satellite relative to the main line was also measured. It was found that the satellite intensity decreased as the cupric complex became covalent. It was also found using this satellite intensity that a cupric complex of (S)-3-aminohexahydroazepine (abbreviated as S-ahaz), [Cu(S-ahaz)₂](BF₄)₂, is directly coordinated by an F atom.

抄録全体を表示

A differential open-ended photoacoustic cell was developed. The cell consists of two equivalent cell chambers and a differential microphone, adapted from an electret condenser microphone. The performance of the differential open-ended photoacoustic cell was compared to 1) that of a conventional air-tight photoacoustic cell and 2) that of a single open-ended photoacoustic cell (with the same dimensions as each of the differential cells and a conventional electret condenser microphone), using a pulse-excited photoacoustic spectrometer. The rejection ratio of background noise was comparable to that obtained by the conventional photoacoustic cell and superior to that of the single open-ended photoacoustic cell. The signals for carbon black obtained by each side of the differential open-ended photoacoustic cell were of comparable amplitude, though the signal waveforms were mirror images of each other. Using these cells, linear relationships between the amount of Sudan Red spotted on filter papers and photoacoustic signal intensities were obtained in the range of 0 to 300ng. The detection limits of Sudan Red were 1.48, 17.9 and 10.14ng, for a conventional photoacoustic cell, a single open-ended cell and the newly devised cell, respectively. The new cell was applied to a human forearm and photoacoustic signals for melanin and red ink on the skin were observed without significant noise.

抄録全体を表示

Temperature-dependent Fourier transform infrared spectra of polyion-complexed synthetic lipid films of dioctadecyl dimethyl ammonium poly(styrene sulfonate), dihexadecylglutamate poly(styrene sulfonate) and two other glutamate-based and diethanolamine-based lipids with a long spacer chain were measured in air and compared with those of liposomal and synthetic bilayer membranes. The antisymmetric CH₂ stretching band of the films showed strong phase transition dependence, indicating that the fundamental conformational changes associated with the phase transition of the lipid films are close to those of aqueous bilayer membranes. However, the films displayed some differences in the spectra; the symmetric CH₂ stretching and carbonyl(ester) stretching band of the films of the glutamate-based lipids did not exhibit phase transition dependence, in sharp contrast with the results of aqueous bilayer systems. This may be due to the retention of higher ordering in the long alkyl chain even at temperatures above the phase transition.

抄録全体を表示

We present an accurate method for determining the concentrations of the major and minor elements in iron-rich and other geological samples using the X-ray fluorescence analysis. A fusion method was used for sample preparation. We used theoretical alpha coefficients which we calculated in order to correct for any matrix effects. For an on-line analysis, we re-calculated the theoretical alpha coefficients using transformation formulas. The analytical results show that the theoretical alpha coefficients can be used to correct the matrix effects, which in this work would greatly reduce the errors for the major components. The final results of an analysis of international reference samples are in good agreement with the recommended concentration values.

抄録全体を表示

Based on a simple model of multivariate calibration, a cross-validation procedure was performed for estimating the number of principal components with the help of singular value decomposition (SVD). The multivariate calibration method with an appropriate number of principal components has been used to determine simultaneously several components in composite aspirin tablets and in composite vitamin B tablets with satisfactory precision and accuracy. The result obtained by the method is very similar to that by partial least squares (PLS) and superior to that by multiple linear regression (MLR). Provided that the matrix composition of the calibration system is similar to that of the analysis system, the method is suitable for the direct or indirect calibration of multicomponent systems or of real samples with incomplete information.

抄録全体を表示

Indeterminate error of dilution with pipette and flask is studied based on experiments, statistics, Monte Carlo simulation and probability theory. Equations which describe the error of sample concentration after the dilution are probabilistically derived and verified experimentally and statistically. The uncertainty structure of dilution is shown to be different for the pipette-pipette dilution and the pipette-flask dilution. The theory for dilution error developed here will be a basis to predict the precision of some chemical analyses such as the internal standard method in chromatography.

抄録全体を表示

Heat-exchange calorimetry has been extended to the flow type. Two glass vessels for the sample and a reference are fixed separately in a precision water bath. In each vessel, a thermistor, a heater element, an inlet of the solution and an outlet for any overflow are installed. Heat released in the sample vessel is freely exchanged with the ambient water. The temperature in each vessel is observed by a thermistor associated with a Wheatstone bridge. The amplified output is introduced into an analog computation circuit in order to calculate the total heat effect. A constant related to the heat transfer of vessels was theoretically found to be proportional to the flow rate; it was subsequently confirmed experimentally by changing the flow rate from 30g/min to zero, corresponding to the batch type. Since the constancy of the peristalsis pumps is not satisfactory, the flow rate at every setting is observed by means of time and mass measurements. The necessary evaluations for precision and reproducibility are executed in water by electric heating; successful results were obtained for practical use.

抄録全体を表示

The effects of the discharge-gas flow rate on ion signals at a constant discharge voltage and current were studied with a Grimm-type glow-discharge ion source attached to a commercial mass spectrometer for inductively coupled plasma mass spectrometry. The ion signals as well as the relative sensitivity factors (RSFs) varied with the gas flow rate to different degrees for different elements and sample materials. The RSF of Cr⁺ in a titanium-base alloy, for example, increased by about four fold along with an increase in the gas flow rate from 4 to 16ml/min. The increase of the gas flow rate did not cause an enhancement of the sputtering rate of the samples, the variation of the ion kinetic energies nor the variation of the atomic emission intensities. Although the reason for the variation of the RSFs with the gas flow rate was not clear, the gas flow rate was found to be an important discharge parameter in glow-discharge mass spectrometry.

抄録全体を表示

The graphite furnace atomic signal of gallium in pure Ar with a pyrolytic graphite (PG) coated tube contained an unresolved double-peak signal. Thermal decomposition of Ga₂O(g) produced by carbon-catalyzed decomposition of Ga₂O₃(s) and an on-surface reduction of Ga₂O₃(s) to Ga(g) are proposed for the atomization mechanisms giving the first and second signals, respectively. A small peak indicating the vaporization of Ga₂O₃ was observed in an old PG tube after 220 firings. In the presence of an organic matrix, the signal was enhanced due to the occlusion of Ga₂O(g) in the porous residue of the pyrolyzed matrix. Addition of oxygen produced a peak on the raising part and another peak on the tailing part of the signal observed in pure Ar. The former peak results from a rapid on-surface reduction of the analyte oxide by active sites renewed on the graphite surface, and the latter peak is the same as the small peak in the old PG tube.

抄録全体を表示

By combining reversed-phase high-performance liquid chromatography (RP-HPLC) with inductively coupled plasma mass spectrometry (ICPMS), the induction of two major metallothionein (MT) isoforms has been demonstrated for a cyanobacterium Anacystis nidulans R-2, cultured under a stress of Zn²⁺ or Cd²⁺. The two isoforms showed only a slight difference in the amino acid composition. Incubation of two Zn-MT isoforms in a medium containing Cd²⁺ led to a metal exchange, reflecting the higher affinity of MT to Cd²⁺ than to Zn²⁺. During this process the relative abundance of the two isoforms remained practically unchanged. The two isoforms were induced in a constant ratio by the Zn²⁺ dosage (1-20μM), while by the Cd²⁺ dosage (0.5-10μM) the ratio showed a change with the dose level. These results demonstrate the potential of the present RP-HPLC/ICPMS system to elucidate the function of MT isoforms.

抄録全体を表示

This report describes a rapid and selective method of sample preparation for the determination of brassinosteroids in samples of biological origin, based on solid-phase extraction. The steroids, brassinolide and castasterone, which possess a C-22, 23-diol group, were retained as their cyclic boronates formed on immobilized phenylboronic acid gel in a mixed solvent of pyridine and acetonitrile. After removal of impurities in the sample, parent brassinosteroids could easily be released from their boronates by a mixed solution of hydrogen peroxide and acetonitrile. The phenylboronic acid phase was shown to have a high affinity for brassinosteroids containing a C-22, 23-diol. The present method is a first example for the selective extraction of brassinosteroids in a biological sample using immobilized phenylboronic acid gel.

抄録全体を表示

A continuous flow chemiluminometric method for determining 10^-8 - 10^-5M of folic acid in pharmaceutical formulations is described. The method is based on the chemiluminescence (CL) produced by the action of cerium(IV) on folic acid in an acidic medium. The emission intensity is greatly enhanced when Rhodamine B is used as a sensitizer. The procedure is automated, requires no sample pretreatment and solutions can be analyzed at a rate of 180 samples h^-1with a relative standard deviation of 0.54% at 1.1×10^-5M folic acid (n=10).

抄録全体を表示

A fluorescent Edman-type reagent, fluorescein isothiocyanate, was adapted for gas-phase sequencing. Samples were covalently attached to functionalized polyvinylidene difluoride (PVDF) membranes or glass filter disks. In the case of sequencing the insulin B chain, the repetitive yields could be improved up to 98% by a covalent attachment of the peptide to an arylamine functionalized PVDF membrane from 74% for noncovalently immobilization on a PVDF membrane. The present method allowed the identification of 20 amino acid residues from the N-terminus with less than 5pmol of the insulin B chain.

抄録全体を表示

A chelating polymer resin having iminodiacetic acid (IDA) as the functional group has been prepared for the selective adsorption of oxo-molybdenum(VI) or oxo-tungsten(VI). The¹³C- and¹H-NMR spectra of these IDA complexes have been studied in the pH range of 4-7 to elucidate the complexation properties of the functional group. The NMR study in the homogeneous system suggests that the IDA forms a 1:1 complex with Mo^VIand W^VIin the pH region 4-7. The peak integration of coordinated acetate signals indicates that the complex formation of IDA is much favorable with Mo^VI than with W^VI. A selective adsorption of Mo^VIover W^VIhas been realized by the chelating resin having an IDA group. A mutual separation of Mo^VIand W^VIhas been demonstrated by the IDA resin in a column system.

抄録全体を表示

Liquid-liquid extraction and the membrane transport of gold(III) have been studied using trioctylamine (TOA). Gold(III) was efficiently extracted with TOA from an HCl solution. The extracted Au^III was instantaneously stripped by an HClO₄ or HNO₃ solution, and subsequently re-extracted at a slow rate. The transport of Au^III was performed across a supported liquid membrane (SLM) impregnated with TOA from an HCl feed solution into an HClO₄ product solution. Most of the Au^III was transported with a reasonable enrichment factor, closely corresponding to the feed-to-product volume ratio.

抄録全体を表示

A solid-state heterogeneous membrane electrode that is selective to sulfate ions was prepared from a poly(vinyl chloride) membrane impregnated with barium chloranilate. Although the electrode response was under Nernstian (16mV/pSO4^2-) it was applicable to a sulfate concentration range of 10^-1.5 to 10^-4mol dm^-3. The preferable pH range was 6-11 and the response time was about 30s. Sulfate ions in organic compounds and polymers can be assayed with this electrode without serious errors at low concentrations of various interfering anions. The electrode remained active
for at least 300 measurements, or 3 months.

抄録全体を表示

Lipid membranes made of lecithin and cholesterol were formed by self-assembly in a small aperture on an agar support. The membranes exhibited an average electric resistance of 135GΩ and a capacitance of 0.43μF/cm². Gramicidin, known to form a channel in uni-lamellar lipid bilayers, reduced the electric resistance to a MΩ level, thus showing the membranes to be of a uni-lamellar bilayer type. The membrane stability was investigated against perturbation with electric potentials and against mechanical agitation in the contacted aqueous solution. About 80% of the membrane preparations remained intact after applying electric potentials of between +1500mV and-1500mV. A similar percentage of the membranes stayed intact under 100rpm magnet stirring in a 30ml vessel. Membranes containing valinomycin responded to K⁺ ions with changes in both the membrane conductance and the membrane potential.

抄録全体を表示