Keiichiro Fuwa

Occurrence of chlorinated polynuclear aromatic hydrocarbons in tap water.

Organic compounds in tap waters were extracted by a modified continuous liquid-liquid extractor and analyzed by computerized gas chromatography/mass spectrometry using a fused silica capillary column. The results indicate the presence of monochlorinated derivatives of naphthalene, dibenzofuran, fluorene, fluorenone, phenanthrene, and fluoranthene and dichlorinated derivatives of naphthalene, phenanthrene, and fluoranthene. The parent polynuclear aromatic hydrocarbons (PAHs) and their oxygenated derivatives such as fluorenone and anthraquinone were also found. It was demonstrated that chlorinated PAHs (Cl-PAHs) were really present in tap waters at 10/sup -1/-10/sup -2/ ng/L levels.

Simultaneous multi-element determination of trace metals in sea water by inductively-coupled plasma atomic emission spectrometry after coprecipitation with gallium

Abstract Coprecipitation with gallium hydroxide is studied for the preconcentration of trace metals in sea water before multi-element analysis by inductively-coupled plasma/atomic emission spectrometry. Gallium precipitates at pH 9 only when magnesium is present. Optimum conditions are established for multi-element preconcentration and removal of matrix elements. The method is almost free from contamination because of the use of highly pure gallium meetal and only a small amount of sodium hydroxide for pH adjustment. Spectral interferences from gallium are negligible and a concentratioin factor of more than 200 can be obtained. Detection limits range from a few ng l−1 to 150 ng l− for Al, Co, Cr, Fe, La, Mn, Ni, Ti, V, Zn, Y and Pb. Artificial and natural sea-water samples can be analyzed with adequate precision.

Seasonal variation of monoterpenes in the atmosphere of a pine forest

Abstract Seasonal variation of monoterpene concentration in the atmosphere of a pine forest was measured and is discussed in relation to various environmental factors. The concentration of monoterpenes was low in winter, and higher and more variable in summer and autumn. Rough seasonal variation may be explained by temperature differences, but changes from day to day are anticorrelated with ozone concentration. The emission rate of monoterpenes from a pine forest was estimated on the basis of atmospheric concentration, going on the assumption that the disappearance of monoterpenes in the forest is governed by atmospheric reactions.

Some spatial characteristics of an atmospheric pressure helium microwave-induced plasma

Abstract In order to characterize an atmospheric pressure helium microwave-induced plasma (M1P) and discuss the excitation mechanisms in the MIP, some spatial distributions of emission intensities of various species. of spectroscopic temperatures, and of electron number density have been determined for the helium M1P, and compared with those of the argon and mixed gas (helium/argon) MIPs sustained under the same operating conditions. The dependences of these parameters on the operating conditions of the M1P have been also examined. For the calculations of electronic excitation, rotational, and ionization temperatures, local thermodynamic equilibrium (LTE) in the M1P was assumed. However, these temperatures showed significant differences from each other. Based on the efficient excitation capability of the helium M1P, even for non-metallic elements, a metastable helium atom mechanism and/or a high-energy electron mechanism have been suggested here as the excitation mechanisms in the helium M1P.

Comparison of spatial distributions of argon species number densities with calcium atom and ion in an inductively coupled argon plasma

Abstract Spatial distributions of calcium atom and ion in an atmospheric pressure argon inductively coupled plasma ICP have been observed in absorption and emission measurements. The number densities of metastable argon and ground state calcium atom and ion in an ICP are estimated from the results. The spatial distributions of temperatures, electron number density, metastable argon number density, and calcium species number densities, are compared, and excitation mechanisms for argon and Ca + and Ca are discussed. Although the ionization temperature for argon is higher than other temperatures, the metastable argon number density agrees with that obtained by assuming an equilibrium at the ionization temperature corrected by taking into account the ionizations of hydrogen and oxygen. The excitation temperature is reduced almost to the gas temperature which is caused by the high collisional rate in the ICP. The thermal and non-thermal excitation mechanisms for analyte have been revealed with the spatial profiles of the emission intensities and absorbances of calcium atom and ion.

Application of an atmospheric pressure helium microwave-induced plasma as an element-selective detector for gas chromatography

Abstract An atmospheric pressure helium microwave-induced plasma (MIP) was combined with a gas chromatograph (GC). and used as an element-selective detector for GC. The detection limits, dynamic ranges and selectivities were obtained for H, C, F, Cl, Br, I and S. Such data for nitrogen and oxygen could not be obtained because of the interference from air which was entrained into the system through the leakages of the tubing and the valve system. The detection limits and dynamic ranges for all the elements investigated were in a range between 1.8 and 39pgs −1 and between 1.6 × 10 3 and 1.1 × 10 5 , respectively. Furthermore, the relative sensitivities of C, H, Cl and Br for various compounds were examined. In the cases of carbon and hydrogen, the relative sensitivities were not the same for different compounds containing oxygen and nitrogen. This result may be explained by the incomplete decomposition of such compounds due to the low microwave power (75 W) applied in the present system.

Simultaneous multi-element analysis by inductively-coupled plasma emission spectrometry utilizing micro-sampling techniques with internal standard

A micro-sampling technique, which requires sample volumes of less than 100 μl, is used for multi-element analysis by i.c.p. emission spectrometry. One drop of sample solution in a teflon cup is nebulized through a capillary tube. Internal standardization with yttrium improves the precision of measurement. The method is applied to the analysis of serum and whole blood samples, after dilution or digestion.

A wavelength table for emission lines of non-metallic elements with transition assignments and relative intensities observed in an atmospheric pressure helium microwave-induced plasma

Abstract The emission lines of 10 non-metallic elements (H, C, N, O, F, Cl, P, S, Br and I) excited by an atmospheric pressure helium microwave-induced plasma have been tabulated with their relative intensities and transitions. These non-metallic elements were introduced into the plasma mostly as the vapor of organic compounds, although the emissions of H, N and O were observed due to the impurities in the helium gas. The spectral lines observed in the wavelength region from 190 to 850 nm were assigned with reference to established wavelength tables and tables of atomic energy levels. All emission line intensities of an element were normalized with respect to the most intense emission line of the element taken as 100.

Spatial distributions of metastable argon, temperature and electron number density in an inductively coupled argon plasma

Abstract Spatially resolved radial distributions of excitation temperature and electron number density in an argon ICP were obtained. The argon excitation temperature and electron number density near the plasma center were found to 7000 K and 5 × 10 15 cm −3 , respectively, at an RF power of 1.5 kW and a carrier argon flow rate 0.65 1 min −1 . Various distributions of the absorbance at the Ar I 811.5 nm line, which has one of the metastable levels as the lower level, were obtained with and without carrier argon flow, where an MIP was used as a light source. Introduction of a large amount of potassium did not influence the distribution of the absorbance. The emission intensities at Ar I 811.5 nm were also measured for comparison.

Simultaneous determination of trace metals in sea water using dithiocarbamate pre-concentration and inductively coupled plasma emission spectrometry

A method based on dithiocarbamate pre-concentration and inductively coupled plasma emission spectrometry is described for the simultaneous determination of cadmium, copper, iron, molybdenum, nickel, vanadium and zinc in sea water. The metals are extracted from 500 g of sea water with ammonium tetramethylenedithiocarbamate-diethylammonium diethyldithiocarbamate in chloroform and back-extracted into nitric acid; the sea water concentration factor is 250 or 500. Advantages of the method include high precision, simplicity of calibration and a detection capability in the nanograms per litre range. The method has been applied to Japan Sea, Pacific Ocean and Atlantic Ocean samples.