Koichi Chiba

Determination of Gallium in Pure Aluminum by Isotope Dilution Analysis with Solvent Extraction Using Inductively Coupled Plasma Mass Spectrometry

Isotope dilution analysis with inductively coupled plasma mass spectrometry (ICP-MS) was applied to the determination of gallium in pure aluminum. Furthermore, a solvent extraction procedure was combined with isotope dilution analysis as a preconcentration technique in order to determine ultra-trace levels of gallium with high precision. The accuracy and the precision of isotope dilution analysis using ICP-MS were compared with those of conventional standard addition analysis using ICP-MS. Isotope dilution analysis gave more accurate and precise results than did standard addition analysis. Isotope dilution analysis with solvent extraction made it possible to measure 0.029 µg/g gallium in 99.999% aluminum with analytical errors at less than 3%.

Evaluation of sulfobetaine-type zwitterionic stationary phases for ion Chromatographic separation using water as a mobile phase

Abstract Ion Chromatographic separation of inorganic ions (anions and cations) was investigated by using three kinds of sulfobetaine-type surfactants (CHAPS, C12SB, and C14SB) as the stationary phases, which were coated by hydrophobic adsorption on the ODS column. In the present separation system, pure water was used as a mobile phase. Since the amount of surfactant adsorbed on the ODS surface significantly influenced the retention behaviors of inorganic ions, the amounts of the sulfobetaine-type surfactants adsorbed were estimated by the breakthrough procedure. The maximum amounts of CHAPS, C12SB and C14SB adsorbed were 0.40, 0.87 and 1.08 mmol, respectively. It was elucidated from the chromatograms of inorganic ions that the retention behavior of inorganic anions was directly related to the surface charges arising from the adsorbed surfactants. The large surface charge was effective for the efficient separation of inorganic ions in water elution. In addition, their retention behavior was strongly affected by the hydrophobicity of the adsorbed surfactants as well as the ionic functional groups of the surfactants which produced the charged surface. The elution order of inorganic anions was correlated with the Hofmeister series. This suggests that the hydration energies of the ions play important roles in separation in the water elution system.

Direct Analysis of Solid Sample with Ultrafine Particle Generation/Inductively Coupled Plasma Emission Spectroscopy

An ultrafine particle generation (UFP) system has been developed for the direct analysis of solid metal samples by inductively coupled plasma (ICP) emission spectrometry. In this system fine particles are generated from solid samples with the use of a spark discharge and then swept into the ICP. The spark discharge conditions involving the electrode gap and the analytical performance of the ICP system are investigated. Analytical calibration curves are presented for steel samples. The NBS standard reference materials are analyzed by the proposed system.

Amphoteric surfactant-modified stationary phase for the reversed-phase high-performance liquid chromatographic separation of nucleosides and their bases by elution with water

A study on surface modification of an octadecylsilica (ODS) column with amphoteric surfactants has been carried out for efficient reversed-phase liquid chromatographic separations of hydrophobic analytes only with water eluent. Two amphoteric surfactants each with different terminal groups (betaine-type and sulfobetaine-type surfactants) were employed as the stationary phase modifier, and the separation characteristics of the modified ODS columns were evaluated by comparing the elution times of nucleosides, their bases, and inorganic ions. In both surfactant-modified ODS column systems, the adsorption of amphoteric surfactant led to a decrease in the retention of nucleosides and their bases, while an increase in the retention of inorganic anions. These results indicate that the amphoteric surfactant adsorbed on the ODS surface suppresses the hydrophobicity of the reversed-phase surface, but it also generates a specific electrostatic field. In other words, the modified ODS columns exhibit hydrophobic/electrostatic mixed-mode separation properties. The degree of the contribution of each property to the separation of analytes can be varied with the amount of the adsorbed surfactant. Consequently, nucleosides and their bases were effectively separated on the ODS column coated with 0.55 mmol of betaine-type surfactant in water elution.

Rapid determination of sulfur in steel by electrolytic dissolution : inductively coupled plasma atomic emission spectrometry

Abstract A rapid determination of sulfur in steel by inductively coupled plasma atomic emission spectrometry (ICP-AES) following an electrolytic dissolution of a solid sample was developed. A solid sample was directly electrolyzed in an electrolysis cell and the resulting electrolyte was on-line introduced into an ICP-AES. The emission intensities obtained by ICP-AES were in linear proportion to the sulfur content in steel. When a sample was electrolyzed with 6xa0M HCl as electrolyte, the emission intensities of sulfur were much higher than those obtained by measuring standard solutions containing sulfate ions. It suggested that sulfur in the electrolyte solution was in the form of H 2 S and introduced into the Ar plasma as H 2 S gas which evaporated from the electrolyte solution during nebulization in a spray chamber. Sulfur in steel was determined at concentration levels of 25xa0μgxa0g −1 with a relative standard deviation of 3.5%. A sample can be analyzed within 60xa0s. The detection limit (3 σ ) of sulfur in steel is 0.6xa0μgxa0g −1 . It was found that large amounts of copper in steel interfered with the sulfur measurement in this analytical system. However, the influence of copper was reduced by using 12xa0M HCl as electrolyte solutions so that steel samples containing copper in sub% level could be analyzed in the present analytical system.