Determination of Ultra-trace Tellurium in Steel by ID-ICP-MS/MS with Liquid-Liquid Extraction.

Inductively coupled plasma mass spectrometry using isotope dilution (ID-ICP-MS) with liquid-liquid extraction was used for determining ultra-trace tellurium (Te) in steels to improve the sensitivity, accuracy, and precision of the analysis. Single quadrupole-type ICP-MS cannot be used to determine the trace amount of Te because of the contribution of mass spectrometric interference by Xe. To overcome this, tandem mass-filter-type ICP-MS (ICP-MS/MS) was used to determine Te. A pretreatment by liquid-liquid extraction was also employed to compensate for the decrease in the signal intensity due to the use of ICP-MS/MS. The relative standard deviations of the resulting abundances, defined by repeated analysis from separated three steel samples, were <1.3%. Furthermore, the determined values of Te in standard reference materials were close to the reference values. Thus, the developed determination method is useful for the analysis of ultra-trace Te in steels.

Effect of Soil Organic Matters in Dredged Soils to Utilization of their Mixtures Made with a Steel Slag.

Dredged soils have been used as construction materials by alkaline activation with steel slag (steel slag-dredged soil mixtures) at harbors. Such mixtures develop strength chiefly by calcium silicate hydrate (C-S-H) formation by the pozzolanic reaction. However, the strength of such mixtures is unpredictable, and in some cases, mixtures have been too soft for the intended engineering application. An identification of strength development indicators would accelerate evaluation processes for strength development to facilitate and promote the utilization of such materials. This paper focuses on the relationship between the characteristics of soil organic matters in dredged soils and the strength development of the mixtures by a comparison of eight dredged soils collected from eight different Japanese harbors. The characteristics of the soil organic matters were identified to determine as indicators of mixtures with weak strength development, i.e., enriched sulfur content in extracted soil organic matter (humic acid) fraction, and the N/C ratio of humic acid similar to land humic acid standards. Increases in the validated fraction of dredged soils and steel slag by replacing fractions disadvantageous to construction resources would contribute to reduce waste production, which would lower the environmental impact of the use, aiming to achieve sustainable utilization of such materials.

Determination of Fluorine Chemical Structure in Slag by Thermal Hydrolysis He-MIP-OES.

A novel microwave-induced helium plasma optical emission spectrometry (He-MIP-OES) combined with a thermal hydrolysis sample introduction system was newly established for the determination of fluorine (F) compounds in slags. The MIP maintained through an Okamoto cavity was adopted, which was quite stable and provided a higher detection capability of F by helium plasma. The basic analytical performance of He-MIP-OES combined with an ultrasonic nebulizer for F analysis was also examined, and expected results could be obtained. The thermal hydrolysis behavior of CaF2, Ca4(Si2O7)(F,OH)2 and Ca5(PO4)3F, as known F chemical structures in slag, was also examined by thermal hydrolysis He-MIP-OES; F compounds in actual slag could be successfully identified and determined by this developed system.

Determination of silicon in high-silicon electrical steel by ICP-AES with on-line sample electrolytic dissolution.

A flow-injection procedure combining electrolytic sample decomposition and inductively coupled plasma atomic emission spectrometry (ICP-AES) is proposed in order to rapidly determine the content of silicon in high-silicon electrical steel. This system is characterized by sample decomposition through electrolysis directly coupled to ICP-AES. A steel sample is dissolved by electrolysis using a 6 mol L(-1) HCl solution as an electrolyte with a flow rate of 5 mL min(-1); the electrolyte containing a dissolved sample is subsequently introduced into ICP-AES via a nebulizer. The effects of the electrolysis current and the temperature on the decomposition of the sample were studied. Samples were electrolyzed under the condition of a 1.5 A constant current, at room temperature (25 degrees C) to avoid the hydrolysis of silicon to precipitate. Comparing the analytical results of steel samples obtained by this analytical system with those obtained by the gravimetric method, determined values agreed well quantitatively. The RSD of silicon at approximately 3% was 0.3% (n = 6).