Determination of Minor and Trace Metals in Aluminum and Aluminum Alloys by ICP-AES; Evaluation of the Uncertainty and Limit of Quantitation from Interlaboratory Testing.

Minor and trace metals in aluminum and aluminum alloys have been determined by inductively coupled plasma atomic emission spectrometry (ICP-AES) as an interlaboratory testing toward standardization. The trueness of the measured data was successfully investigated to improve the analytical protocols, using certified reference materials of aluminum. Their precision could also be evaluated, feasible to estimate the uncertainties separately. The accuracy (trueness and precision) of the data were finally in good agreement with the certified values and assigned uncertainties. Repeated measurements of aluminum solutions with different concentrations of the analytes revealed the relative standard deviations of the measurements with concentrations, thus enabling their limits of quantitation. They differed separately and also showed slightly higher values with an aluminum matrix than those without one. In addition, the upper limit of the detectable concentration of silicon with simple acid digestion was estimated to be 0.03 % in the mass fraction.

Evaluation of Relative Sensitivity Factors for Elemental Analysis of Aluminum and Magnesium Using Glow Discharge Mass Spectrometry with a Fast-Flow Grimm-type Ion Source.

Relative sensitivity factors on glow discharge mass spectrometry were evaluated for unalloyed and alloyed metals of aluminum and magnesium using a glow discharge mass spectrometer operated with fast flow Grimm-type source. All the elements measured could be classified into two groups, i.e. a group of elements could be determined with repeatability equal to or less than 15% relative standard deviation, while another group could be determined with RSDs of greater than 15%. The latter is mainly due to the instability of discharge condition and elemental segregation onto certified reference materials.

Determination of oxygen content in magnesium and its alloys by inert gas fusion-infrared absorptiometry.

A method for the determination of the oxygen content in magnesium and magnesium alloys has been developed. Inert gas fusion-infrared absorptiometry was modified by introducing a multistep heating process; a sample containing oxygen is fused with tin to form an eutectic mixture at 900°C in a graphite crucible, followed by a subsequent gradual temperature increase of up to 2000°C, which enables the evaporation of magnesium from the mixture, and subsequent solidification at the rim of the crucible. Residual tin including magnesium oxide remained at the bottom of the crucible. The oxygen in the tin is measured by a conventional inert gas fusion (IGF) method. From a comparison with the results of charged particle activation analysis, the IGF method is considered to be an attractive candidate for measuring the oxygen content in Mg and its alloys.

Interlaboratory testing for the determination of trace amounts of tin and lead in magnesium and magnesium alloys by inductively coupled plasma atomic emission spectrometry.

In order to establish a standard analytical method for the determination of trace amounts of tin and lead in magnesium and its alloys, which could be found in neither JIS nor ISO standards, an interlaboratory testing with inductively coupled plasma atomic emission spectrometry (ICP-AES) has been put into practice. Simple dissolution with nitric and hydrochloric acids and sample nebulization procedures were finally concluded to be suitable for standardization. The analytical methods, proposed in this study have been provided as newly established JIS standards.

DMPO-OH radical formation from 5,5-dimethyl-1-pyrroline N-oxide (DMPO) in hot water.

When an aqueous solution of 5,5-dimethyl-1-pyrroline N-oxide (DMPO) was heated at 70 degrees C for 30 min, formation of DMPO-OH was observed by ESR. This DMPO-OH radical formation was suppressed under an argon atmosphere. When water was replaced with ultra-pure water for ICP-MS experiments, DMPO-OH radical formation was also diminished. Under an argon atmosphere in ultra-pure water, the intensity of the DMPO-OH signal decreased to about 1/20 of that observed under aerobic conditions with regular purified water. The addition of hydroxyl radical scavengers such as mannitol did not affect the formation of DMPO-OH, but the signal turned faint in the presence of EDTA. We suggest that DMPO reacted with dissolved oxygen to form DMPO-OH.

Development and optimization of a lab-on-a-chip device for the measurement of trace nitrogen dioxide gas in the atmosphere.

We propose the use of lab-on-a-chip technology for measuring gaseous chemical pollutants, and describe the development of a microchip for the detection of nitrogen dioxide (NO2) in air. A microchip fabricated from quartz glass has been developed for handling the following three functions, gas absorption, chemical reaction and fluorescence detection. Channels constructed in the microchip were covered with porous glass plates, allowing nitrogen dioxide to penetrate into the triethanolamine (TEA) flowing within the microchannel beneath. The nitrogen dioxide was then mixed with TEA and reacted with a suitable fluorescence reagent in the chemical reaction chamber in the microchip. The reacted solution was then allowed to flow into the fluorescence detection area to be excited by an ultraviolet light-emitting diode (UV-LED), and the fluorescence was detected using a photomultiplier tube (PMT). The reaction time, reagent concentration, pH, flow rate and other measurement conditions were optimised for analysis of nitrogen dioxide in air. Preliminary studies with standardized test solutions revealed quantitative measurements of nitrite ion (NO2-), which corresponded to atmospheric nitrogen dioxide in the range of 10-80 ppbv.