Hiroki Haraguchi

Metallomics as integrated biometal science

In this paper, “metallomics” is proposed as a new scientific field in order to integrate the research fields related to biometals. Metallomics should be a scientific field in symbiosis with genomics and proteomics, because syntheses and metabolic functions of genes (DNA and RNA) and proteins cannot be performed without the aid of various metal ions and metalloenzymes. In metallomics, metalloproteins, metalloenzymes and other metal- containing biomolecules are defined as “metallomes”, in a similar manner to genomes in genomics as well as proteomes in proteomics. Since the identification of metallomes and the elucidation of their biological or physiological functions in the biological systems is the main research target of metallomics, chemical speciation for specific identification of bioactive metallomes is one of the most important analytical technologies to establish metallomics as the integrated bio-metal science. In order to rationalize the concept of metallomics, the distributions of the elements in man, human blood serum and sea-water, a challenge to all-elements analysis of one biological cell, and some other research topics are introduced with emphasis on recent development of chemical speciation of trace metals in some biological samples.

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.

Multielement determination of trace metals in seawater by ICP-MS with aid of down-sized chelating resin-packed minicolumn for preconcentration.

The multielement determination of trace metals in seawater was carried out by inductively coupled plasma mass spectrometry (ICP-MS) with aid of a down-sized chelating resin-packed minicolumn for preconcentration. The down-sized chelating resin-packed minicolumn was constructed with two syringe filters (DISMIC 13HP and Millex-LH) and an iminodiacetate chelating resin (Chelex 100, 200-400mesh), with which trace metals in 50mL of original seawater sample were concentrated into 0.50mL of 2M nitric acid, and then 100-fold preconcentration of trace metals was achieved. Then, 0.50mL analysis solution was subjected to the multielement determination by ICP-MS equipped with a MicroMist nebulizer for micro-sampling introduction. The preconcentration and elution parameters such as the sample-loading flow rate, the amount of 1M ammonium acetate for elimination of matrix elements, and the amount of 2M nitric acid for eluting trace metals were optimized to obtain good recoveries and analytical detection limits for trace metals. The analytical results for V, Mn, Co, Ni, Cu, Zn, Mo, Cd, Pb, and U in three kinds of seawater certified reference materials (CRMs; CASS-3, NASS-4, and NASS-5) agreed well with their certified values. The observed values of rare earth elements (REEs) in the above seawater CRMs were also consistent with the reference values. Therefore, the compiled reference values for the concentrations of REEs in CASS-3, NASS-4, and NASS-5 were proposed based on the observed values and reference data for REEs in these CRMs.

Speciation of mercury compounds in waste water by microcolumn liquid chromatography using a preconcentration column with cold-vapour atomic absorption spectrometric detection

Abstract A microcolumn liquid chromatographic method with cold-vapour atomic absorption spectrometric detection was developed for the speciation of mercury compounds in waste water. The sample solution containing mercury at the 4-ng level was injected onto a preconcentration column (27 mn × 0.51 mm i.d.) packed with Develosil-ODS (30 μm) and eluted with cysteine-acetic acid through a separation column (125 mm × 0.5 mm i.d.) packed with STR-ODS-H (5 μm). After oxidation, tin(II) chloride in sodium hydroxide solution was used to reduce mercury compounds to mercury. The generated mercury vapour was swept from a gas-liquid separator by argon into the detector cell and monitored at 253.7 nm. Mercury(II) chloride, methylmercury chloride and ethylmercury chloride, were well resolved and the determination was completed in less than 16 min. The method was successfully applied to the speciation of mercury compounds in waste water.

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.

Measurement of Small Volume Flame Temperatures by the Two-line Atomic Fluorescence Method

Measurement of small volume temperatures of analytical flames by the two-line atomic fluorescence technique involving the use of direct-line Stokes and anti-Stokes fluorescence of indium and thallium has been examined. Spatial flame temperatures have been measured with a volume resolution of 0.3 mm by 2 mm by 5 mm in the flame. Theoretical and practical considerations of the method are given, particularly in terms of the limitation of using indium or thallium. The use of the two thallium lines (377.57 and 535.05 nm) was subject to fewer random errors than the use of the two indium lines (410.18 and 451.13 nm) for the range of temperatures studied. However, thallium lines are restricted to the measurement of temperatures above about 2000°K (for the air-acetylene and nitrous oxide-acetylene flames); for temperatures below about 2000°K, the fluorescence irradiance ratio could not be measured with sufficient signal/noise ratio due to the low intensity of the anti-Stokes fluorescence line. In the present experiment, indium lines were used for the measurement of a wide range of “low” flame temperatures (approximately 700 to 2600°K) owing to the better signal/noise ratios for both lines; indium lines were also preferable for the air-acetylene flame, even though the error produced by the random uncertainty in the fluorescence ratio was larger than for thallium. The present method has been successfully applied to the measurement of the spatial temperature profiles of analytical flames, such as argon-hydrogen(-entrained air), argon-oxygen-hydrogen, air-acetylene, and nitrous oxide-acetylene.

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.