BUNSEKI KAGAKU Abstracts

Vol. 53 No. 11

November, 2004

Research Papers

Extraction of lanthanoids(III) with several β-diketones and the formation of aqueous chelates

Azusa Oga¹, Kazuaki Yamaoka¹, Kazuyuki Itano¹ and Yuko Hasegawa¹

(Received 26 May 2004, Accepted 26 August 2004)

The extraction constants represented by K_ex=[LnA₃]^o[H⁺]³[Ln³⁺]^-3[HA]^o-3 were determined across the lanthanoid series, in the extraction of lanthanoids(III) with acetylacetone (H_aa), benzoylacetone (H_bza), benzoyltrifluoroacetone (H_bfa), and hexafluoroacetylacetone (H_hfa) from 0.1 mol dm^-3 NaClO₄ into CHCl₃ at 25°C. The extraction constants increased along with increasing the lanthanoid atomic number. However, the degree of the variation of the extraction between adjacent lanthanoids decreased in the sequence of H_aa≥H_bza>H_bfa>H_hfa, i.e., the extraction constants with β-diketones, possessing a smaller number of F atoms, showed the larger variation for the lanthanoid. In addition, when the stability constants of the aqueous chelates of lanthanoids(III) with Hhfa and Haa were determined by potentiometric titration and the solvent-extraction technique, the constants of the aa chelates increased along with the atomic number, while those of the hfa chelates did not change over the series. Accordingly, it was concluded that the increase of Kex with Haa for the lanthanoid series depends on the change in the stability constants as well as the distribution constants of the extracted species, while the similar values of Kex with Hhfa across the series was contributed by similar stability constants.

Keywords : lanthanoids(III); extraction constants; stability constants; β-diketones; distribution constants of the extracted chelates.

Excitation behavior of chromium emission lines from a radio-frequency glow discharge plasma associated with bias-current introduction

Kenji Kodama¹ and Kazuaki Wagatsuma¹

(Received 7 May 2004, Accepted 16 September 2004)

The introduction of a d.c. bias current to an r.f. glow-discharge plasma led to an intensity increase of particular emission lines. It was considered that the excitation mechanism was investigated based on Boltzmann plots of chromium emission lines with and without the introduction of a bias current. In the case of Cr I lines, the Boltzmann plot follows a straight lines without bias-current introduction, whereas it bends upwards when a bias current is introduced. This effect could be explained from the fact that the excited levels having energies of 4.2 eV and 5.8 eV were more populated compared to the excited levels of 3.3 eV through collisions with introduced electrons. On the other hand, the Boltzmann plot of Cr II lines bends downwards with no bias currents, which is caused by the selective excitation of Cr ion species having excitation energies of 8 eV through charge-transfer collisions between Cr atoms and Ar ions. When bias currents were introduced, the charge transfer collisions could be less effective, leading to a straight-line relationship of the Boltzmann plot of the Cr II lines. These results effects suggest that introducing a bias current is effective to enhance the intensities of not only the Ni or Cr atomic emission lines, but also the other atomic-emission lines.

Keywords : r.f. glow-discharge plasma; Grimm glow lamp; enhancement of emission intensity; Boltzmann plot; chromium.

Size fractionation of iron compounds in phytoplankton cultures in the presence of chelating ligands

Chikako Okumura¹, Hiroshi Hasegawa¹, Hidenobu Mizumoto¹, Teruya Maki¹ and Kazumasa Ueda¹

(Received 10 May 2004, Accepted 16 September 2004)

We determined iron speciation in laboratory cultures containing a radioactive tracer, ⁵⁵Fe, and chelating ligands using a size-fractionation method. For the size-fractionation of iron, filters with 0.025, 0.20 and 3.0 mm pore size were used. In the media with chelating ligands, major species of iron were colloidal and truly dissolved fractions. When cells of phytoplankton were added, the colloidal fractions decreased, while the large particle fractions (>3.0 mm) increased in the cultures. The iron uptake of phytoplankton, especially extracellular iron, was correlated with the colloidal iron fractions, of which the concentrations depended on the chelating ligands in the media. It is likely that phytoplankton absorbed the colloidal iron fractions onto the cell surface and that utilized the fractions as an iron source in the cultivated media.

Keywords : iron; speciation; chelating ligands; phytoplankton growth.

Selective collection of metal ions with a trithioether derivative and poly-N-isopropylacrylamide

Miho Segawa¹, Shouko Kobayashi¹, Haruo Tuji¹ and Kenji Chayama¹

(Received 10 May 2004, Accepted 16 September 2004)

A polymer-mediated extraction system using 1,9-diphenyl-2,5,8-trithianonane (9-2Ph-SSS) as extractant and Poly-N-isopropylacrylamide (PNIPAAm) as an extraction medium for noble metal ions was examined. The system was compared with the liquid-liquid extraction system using the same ligand and 1,2-dichloroethane as an organic solvent. The results showed that soft metal ions (class b metal ions) were extracted well as the metal trithioether complex by both systems. On the other hand, class ab metal ions such as cobalt(II), nickel(II), manganese(II), copper(II) and zinc(II) ions were incorporated into solid phase of the polymer as hydroxide at pH higher than 6. A masking agent EDTA was added to polymer mediated system to prevent the formation of hydroxide, resulting in a highly selective extraction system for noble metal ions, such as silver(I), copper(I) and palladium(II) as well as the liquid-liquid extraction system.

Keywords : Poly-N-isopropylacrylamide; 1,9-dipheneyl-2,5,8-trithianonane; extraction.

Notes

Dissolution method for the determination of silicon in plant samples with ICP-AES

Koich Akiyama¹, Tadashi Nakanishi¹, Ryo Ohnishi¹ and Tasuku Akagi¹

(Received 7 May 2004, Accepted 21 September 2004)

Dissolution methods for the determination of silicon in plant samples with inductively coupled plasma atomic emission spectrometry (ICP-AES) were examined. Plant samples (0.1 g) ashed by an electric furnace at 700°C were dissolved by three methods: an acid dissolution method, where the ashes were dissolved with a hydrochloric acid solution; an alkaline dissolution method, where the ashes were dissolved with a sodium carbonate solution; and an alkaline fusion method, where the ashes were fused with sodium carbonate salt. The effect of evaporation after dissolution was also examined. It was found that evaporation exerted a critical effect on the analytical results of silicon, i.e., complete evaporation reduced the results to about half that obtained with incomplete evaporation. Two tea leaf samples (commercial and sampled) with a low silicon concentration could be dissolved by all three methods when the resultant solution was followed by incomplete evaporation. The reproducibility of the silicon concentration with the alkaline dissolution method and acid dissolution method was about 3%, and the recovery of silicon after both methods was more than 95%. In the case of Magnolia leaves with a high silicon concentration, the alkaline dissolution method gave a greater concentration of silicon with better precision (5%) than the alkaline fusion method.

Keywords : plants; silicon; dissolution methods; alkaline dissolution; alkaline fusion.

Analytical Reports

Evaluation of diesel exhaust particle pollution using the source apportionment of PM_2.5 in an urban atmospheric environment

Takanori Takii¹, Kenichirou Suzuki¹, Satoshi Nakano¹, Miyuki Yoshizawa¹, Masashi Nojima¹, Bunbunoshin Tomiyasu² and Yoshimasa Nihei¹

(Received 17 May 2004, Accepted 5 September 2004)

We performed a source apportionment for particulate matter under 2.5 µm with the diameter (PM_{_2.5}) based on individual particle analyses using an electron probe microanalyzer (FE-SEM/EPMA). The analyzed particles were collected from the air environment near to a traffic route in June (before diesel vehicle emissions control regulations) and December (after regulations) 2003. From the results of the size, shape, and components of the particles, five or more sources of the particles were estimated. The rates for the contribution of diesel exhaust particle (DEP) were higher than that of the other sources. DEPs were further classified based on information concerning light elements according to the X-ray spectrum patterns. The X-ray spectrum patterns of DEPs collected before diesel vehicle emissions control regulations were different from that collected after the regulations. We could obtain this information about PM_2.5 and DEPs, which could not be obtained by the conventional method. Therefore, it is concluded that the combination of individual particle analysis based on FE-SEM and EPMA is one of the most powerful techniques for obtaining detailed information about PM_2.5.

Keywords : PM_2.5; DEP; EPMA; FE-SEM; individual particle analysis.

Reviews

Complex formation of non-cyclic polyoxyethylenes and their application to analytical chemistry

Kiyoshi Sawada¹ and Yoichi Kikuchi²

(Received 21 April 2004, Accepted 4 June 2004)

The complex formation of non-cyclic linear polyoxyethylenes and their alkyl derivatives (POE compounds) and application to analytical chemistry are reviewed. The POE compounds form the complexes with alkali and alkaline earth metal ions in the same manner as the cyclic one (crown ether). Although the selectivity and stability of the complex formation are inferior to that of crown ether, POE compounds are interesting material because they have flexible structure and the compounds having a very long ethylene oxide (EO) unit are available. The structures of the crystalline complexes have been determined as the metal ion is surrounded by EO moieties and similar structures are estimated for the complexes in solution. Generally they form 1:1 complexes with a metal ion. In case of long chain POE compounds, however, polynuclear complexes are formed. POE compounds are widely used as non-ionic surfactants (NIS). The complexation of POE compounds has been applied to various separation and determination methods, such as solvent extraction, trace analysis of NIS and metal ions and so on. Peculiar properties of POE compounds as NIS have been also utilized for various analytical methods.

Keywords : linear polyoxyethylene; non-cyclic polyether; ethylene oxide; complex formation; solvent extraction; ion-pair extraction; determination of non-ionic surfactant; alkali and alkaline earth metal ions.

Development of collision/reaction cell for reduction of spectral interference in ICP mass spectrometry

Junichi Takahashi¹ and Noriyuki Yamada¹

(Received 29 March 2004, Accepted 29 June 2004)

Among the various methods applied to reduce spectral interference in ICP-MS, collision technology, which utilizes gaseous molecules to eliminate interfering ions, has been demonstrated to be one of the most effective techniques. Helium, hydrogen, ammonia, methane and oxygen are mainly used as collision gases. Although by-product ions are sometimes found as a result of the ion-molecule reactions involved in this technology, these undesirable ions are successfully suppressed by energy discrimination, or a band-pass tuning technique. The principle of the technology, the optimization method of the instrumental parameters and the major applications to various samples are described along with comments on the possibilities and limitations of the technology.

Keywords : ICP-MS; collision cell; reaction cell; CCT; DRC; ORS.

Accounts

Elucidation of specific ion association in non-aqueous solution environments

Masashi Hojo¹

(Received 14 April 2004, Accepted 17 June 2004)

In aqueous solution, alkali metal and alkaline earth metal salts are regarded to be “indifferent salts” or supporting electrolytes, which should change the activity coefficients of ionic species. Although higher ion aggregates from 1:1 type electrolytes in low-permittivity media (ε_r<10) are widely accepted, only few chemists have recognized higher ion aggregation in higher permittivity media. However, we have clarified that the chemical interaction, such as coordination, can operate between anions and cations in non-aqueous solvents (20<ε_r<65) of low solvation ability. Acids (HA) and their conjugate base anions (A^-) may react with each other to form homoconjugated species, such as A^-(HA)₂, in acetonitrile or benzonitrile, protophobic aprotic solvents with low hydrogen-bonding donor and acceptor abilities. After observing the direct reaction of some anions (e.g. Cl^-) and cations (e.g. Li⁺) toward a certain species, we comprehensively interpreted the salt effects in chemical equilibria, based on distinct chemical interactions and not merely a vague term, “medium effect”. A reaction manner similar to that in non-aqueous solution can take place, even in some “aqueous” solution, if the water structure of the aqueous solution is completely destroyed, because the properties of bulk water should arise from a huge network of water molecules by hydrogen bonding; otherwise, the properties of water must be reduced to just those of isolated H₂O molecules, termed, “dihydrogen ether”. The chemical interaction between ions has been proved in “aqueous” solution of low water-structuredness with the addition of concentrated salts and non-aqueous solvents; a minor increase of the intermediate species that would never be observed in the chemical equilibrium sense could be multiplied into a measurable change in the chemical kinetics.

Keywords : non-aqueous solvent; acetonitrile; ion association in higher permittivity medium; water structure by hydrogen bonding; property of bulk water.

Research Papers

The rapid analysis for residual pesticides by tandem mass spectrometry with immunoaffinity extraction

Hiroyuki Nakazawa¹, Yukiko Kanzaki¹, Nobuyuki Takahashi¹ and Hisao Oka²

(Received 8 January 2004, Accepted 7 June 2004)

A new strategy, based on immunoaffinity extraction coupled with flow-injection-electrospray tandem mass spectrometry (IAE-FI-MS/MS), has been developed for a screening method of phenoxy acid herbicides. This method uses polyclonal antibody produced against a protein for conjugating the phenoxy acid herbicides. Silvex, Mecoprop, Dichlorprop and 2,4-D were monitored in the multiple reaction monitoring (MRM) mode with the selection of m/z 267/195 for Silvex, m/z 213/141 for Mecoprop, m/z 233/161 for Dichlorprop and m/z 219/161 for 2,4-D, respectively. The use of highly selective IAE in sample preparation prior to FI-MS/MS analysis allowed the removal of interfering compounds present in the sample extracts, that would cause severe ionization suppression of the phenoxy acid herbicides during the electrospray process. In addition, the analysis time, including sample preparation and determination for 96 samples, required only 100 minutes for the screening for residual Silvex, Mecoprop, Dichlorprop and 2,4-D by using a 96-well microtiter plate.

Keywords : immunoaffinity extraction; FI-MS/MS; phenoxy acid herbicides; 96-well micro titer plate; ELISA.

Technical Papers

Compact electroanalytical instruments for quantitative semimicro analysis experiments

Yasutada Suzuki¹, Takayuki Ito¹, Tsugio Fukasawa¹, Susumu Kawakubo¹ and Masaaki Iwatsuki¹

(Received 6 May 2004, Accepted 14 June 2004)

Two electroanalytical instruments, such as a power supply for electrogravimetry and a constant-current coulometric analyzer, were developed for quantitative semimicro analysis experiments in an undergraduate course. The power supply for electrogravimetry contained a variable-voltage power supply and an electronic load; they controlled the potential and current of electrolysis, respectively. It also contained an embedded controller and a liquid-crystal display (LCD), and could display the potential and current. It was applied to the determination of copper in copper(II) sulfate pentahydrate. The obtained results were 98~103% of theoretical values. On the other hand, the coulometric analyzer contained a constant-current power supply for electrogeneration of the titrant, a constant-voltage power supply for the indicator circuit, an amplifier and an analog-to-digital converter for the indicator current measurement, and an embedded controller and an LCD to display the indicator current and the elapsed time of electrolysis. It was applied to the determination of thiosulfate with electrogenerated iodine. The obtained results were in good agreement with a conventional instrument. Both instruments were not only applicable to quantitative semimicro analysis experiments, but also their dimensions and power consumption were markedly reduced.

Keywords : compact electroanalytical instrument; quantitative semimicro analysis; experiments in undergraduate course; electrogravimetry; constant-current coulometry.

Wetting property and capillarity of stationary phase for reversed phase liquid chromatography

Toshiyuki Enami¹ and Norikazu Nagae¹

(Received 6 May 2004, Accepted 29 July 2004)

The retention behavior of the reversed phase was evaluated under 100% aqueous conditions. It is commonly said that reversed phases, such as ODS (C₁₈) and C₈, show a decrease of the retention time under 100% aqueous conditions. It was previously reported that the mechanism of the decrease in retention was found to be that the 100% aqueous mobile phase was expelled from the pore of the packing materials, so that the stationary phase in contact with the mobile phase decreased. In this study, the wettability between the C₁₈ stationary phase and water as a mobile phase was analyzed. It was concluded that the retention behavior could explained by capillarity, and reversed-phase separation could be carried out under 100% aqueous conditions, even if a mobile phase can not wet the stationary phase.

Keywords : retention; reversed phase; water.

Notes

Determination of cyanide ion with gas-liquid separation tube and monitoring tape

Mitsuyoshi Hoshino¹, Kunio Nagashima¹, Minori Kamaya¹ and Nobuo Nakano²

(Received 23 April 2004, Accepted 14 June 2004)

A sample solution was pumped at a flow rate of 3 ml min^-1 to the mixing joint, where a sulfuric acid(0.05 M) was mixed at a rate of 2 ml min^-1. A mixture containing hydrogen cyanide was fed into a gas-liquid separation tube(pore size, 1 mm; microporous Teflon tube of 2 mm i.d., 3 mm o.d., 900 mm length). Hydrogen cyanide evolved from the gas-liquid separation tube was purged by purified air (400 ml min^-1) onto HCN monitoring tape. The efficiency of the gas-liquid separator used was about 3%. The monitoring tape used was porous cellulose tape containing silica gel, N,N-diethyl-p-phenylenediamine, Cu(CH₃COO)₂ and glycerin. When the tape was exposed to HCN gas, the tape became colored homogeneously. The degree of color intensity was proportional to the concentration of CN^- in the sample solution. The relative standard deviation of the response to 0.1 mgCN^- dm^-3 was 1.2%. The calibration curve showed a rectilinear behavior in the range of 0.01~0.3 mgCN dm^-3. The method has detection limits of 0.01 mgCN dm^-3 for free cyanide ion with a sampling time of 5 min. This method could detect free cyanide ions, and indirectly Cu(II) and Cd(II) cyano complexes when the metal concentrations were below 10 mg dm^-3.

Keywords : determination of cyanide ion; gas-liquid separation tube; HCN gas monitoring tape; metal cyano complex; N,N-diethyl-p-phenylenediamine.

Selective determination of dopamine based on a self-assembled monolayer electrode with antifouling activity on protein adsorption

Zhidong Chen¹ and Tsutomu Nagaoka²

(Received 5 March 2004, Accepted 26 June 2004)

A self-assembled monolayer consisting of 3,3'-thiodipropionic acid and n-decyl mercaptan formed on a gold electrode was studied for a sensitive and selective determination of dopamine. The experimental results show that the monolayer exhibits both excellent sensitivity and stability, even in the presence of ascorbic acid and protein. A detection limit of 5.0×10^-6 M for dopamine was obtained in flow injection analysis by the optimizing experimental conditions, such as the solution pH, flow velocity of the carrier solution and the electrode potential. The current response of the modified electrode showed excellent stability in the presence of 0.2% albumin. Even with ascorbic acid in 10-fold excess, dopamine could be detected within an error of about 3%.

Keywords : self-assembly electrode; amperometric flow-injection analysis; dopamine; ascorbic acid; protein adsorption.

Thin-layer chromatography of rare earths in a carboxymethyl cellulose-aqueous sodium nitrate system, and the separation of yttrium

Yoichi Takeda¹ and Koji Ishida¹

(Received 12 April 2004, Accepted 29 June 2004)

The adsorption behavior of all the rare earths, except for promethium, was surveyed on carboxymethyl cellulose thin layers in sodium nitrate solutions as a function of the concentration of salt. At lower salt concentrations, the R_f values of the lanthanoids showed an S-shaped variation with their atomic number, and yttrium lay near to lanthanum, relatively analogous to the adsorption behavior in chloride solutions. At higher salt concentrations, the behavior of the metals was considerably different from that in the chloride solutions, and the R_f values of the lanthanoids decreased with an increase of their atomic number. The R_f value of yttrium gradually approached that of europium with increasing salt concentration in nitrate media. Two-dimensional development appeared first with a 0.5 M sodium chloride solution and second with a 5 M sodium nitrate solution, allowing yttrium to be separated from all of the rare earths.

Keywords : rare earths; yttrium; thin-layer chromatography; carboxymethyl cellulose; aqueous sodium nitrate solutions.

Application of solvent extraction method to the determination of magnesium in hard tissues of shellfish by ICP-AES

Hiroaki Fukui¹, Osamu Fujino² and Shigeo Umetani³

(Received 14 April 2004, Accepted 9 July 2004)

The magnesium in hard tissues (shell and pearl) of shellfish inhabiting freshwater and sea water was determined by inductively coupled plasma-atomic emission spectrometry (ICP-AES) after solvent extraction separation. We examined whether ICP-AES signals for magnesium were highly suppressed, or increased by large amounts of calcium ions. Two interferences, spectral and physics, were generated by the macro-component calcium for the emission intensity of magnesium. These interferences occurred simultaneously for magnesium. In addition, the calcium of the large excess adhered to a quartz torch, and the tip minute of the torch was damaged. From these results, it became cleare that it is necessary to separate magnesium from calcium prior to a measurement by ICP-AES. To eliminate this problem, we applied the solvent extraction method to separate magnesium from the interfering element, calcium. The chelating agent was easy to form the chelate with magnesium, and then a reagent that could extract the chelate from the acid solution was chosen. 1-phenyl-3-methyl-4-trifluoroacetyl-5-pyrazolone (HPMTFP) having a pK_a value of 2.56 was chosen as the extraction reagent. Also, we selected some organic solvents in which the carbon did not adhere to torch without extinguishing plasma on the extractant. The sample solutions of shell and pearl used in the present work were treated with hot concentrated nitric acid, hydrochloric acid and perchloric acid. Magnesium was extracted with 0.01 mol/l-HPMTFP in dibutyl ether at pH 4.5 in order to separate it from the interfering calcium. Magnesium was determined by ICP-AES, and direct injection of the dibutyl ether. The magnesium content in the shell and pearl was found to be 16.4~2627 µg/g.

Keywords : ICP-AES; hard tissues of shellfish; solvent extraction; 1-phenyl-3-methyl-4-trifluoroacetyl-5-pyrazolone; magnesium.

Analytical Reports

Preparation and certification of new reference materials Forest soils (JSAC 0421 and JSAC 0422) for the determination of dioxins

Kensaku Okamoto¹, Takashi Imagawa¹, Hiroyasu Ito¹, Masahiro Takeuchi¹, Shin-ichi Yamasaki¹, Akiko Ochi¹, Naomi Ito¹, Takafumi Kida¹, Satoshi Tsuruta¹, Kazutoshi Kakita¹, Akihiro Ono¹ and Mamoru Sakata¹

(Received 12 May 2004, Accepted 20 July 2004)

The Japan Society for Analytical Chemistry has developed two new certified reference materials (CRMs) for dioxins and coplanar PCBs. A project team was organized to prepare 2 kinds of forest soil and to certify the concentration of dioxins. An interlaboratory comparison test was performed with the participation of 15 laboratories. In a statistical, analysis, z-scores in the “robust method” were applied to estimate the degree of bias of reported data from the mean value in order to reject any data with a big bias, and was followed by the usual statistical procedure. The presented CRMs are expected to be useful for the quality assurance and quality control of dioxins analysis.

Keywords : dioxins; soil; interlaboratory comparison test; certified reference material.

Results of proficiency testing for determination of dioxins in fly-ash (1st round) based on ISO/IEC Guide 43-1

Yo-ichi Ishibashi¹, Shozo Asada¹, Hiroyuki Igaki¹, Shu-ichi Yamada¹, Satoshi Tsuruta¹, Makoto Shimura¹, Kazutoshi Kakita¹, Akihiro Ono¹ and Mamoru Sakata¹

(Received 16 April 2004, Accepted 23 July 2004)

The Japan Society for Analytical Chemistry carried out proficiency testing on the determination of dioxins (polychlorodibenzo-p-dioxins, polychlorodibenzofurans and coplanar polychlorobiphenyls) in fly-ash of a waste incinerator. The proficiency testing of analytical laboratories is based on ISO/IEC Guide 43-1 “Proficiency testing by interlaboratory comparisons”. This testing was carried out from November 2000 to March 2001, with the participation of 41 laboratories. The test results were; 0.987 ng-TEQ/g of total dioxin concentration on the average, 13% in robust standard deviation. Two labs were judged to be unsatisfactory because of their large z-score in the robust method (over 3 in absolute value).

Keywords : proficiency testing; dioxins; fly-ash; GC-MS analysis.

Determination of silicon and copper in aluminium alloy for semiconductor devices using ICP-OES after sodium hydroxide-nitric acid decomposition

Hiroshi Mitsumata¹, Toshio Mori¹ and Kazuo Saimoto¹

(Received 21 April 2004, Accepted 26 July 2004)

We have established a method for assaying the quantities of silicon and copper in aluminium alloys deposited by sputtering on silicon substrates. This method involves the following procedure: 1) The alloy film is peeled away with a metal blade, while taking care not to damage the silicon substrate. 2) The peeled film is dissolved in a hot 1% aqueous solution of sodium hydroxide. 3) The solution is acidified with nitric acid, and the quantities of silicon and copper are assayed by inductively coupled plasma optical emission spectrometry(ICP-OES). We have clarified that this method can assay silicon and copper in as little as 20 mg of peeled aluminium alloy.

Keywords : ICP-OES; SEM; aluminium alloy; aluminium alloy film; aluminium alloy for semiconductor device; silicon; copper.

Digests of Doctoral Dissertation

Development of novel separation media having selective molecular recognition ability

Takuya Kubo

Graduate School of Environmental Studies, Tohoku University, Aramaki-aza Aoba 6-6-20, Aoba-ku Sendai-shi, Miyagi 980-8579

(Awarded by Kyoto Institute of Technology dated March 25, 2004)

The author has developed novel separation media for harmful compounds in the environment. At first, polymer based separation media for high performance liquid chromatography (HPLC) and capillary electrochromatography (CEC) were prepared by novel surface modification methods with functional monomers. The results of HPLC and CEC evaluations have suggested that the functional monomers were introduced on the external surface of the separation medium by the addition method, while were introduced into the internal surface in the case of the dispersion method. Additionally, the separation medium modified with both anion and cation exchangeable monomers by the addition method realized the stimulus responsive property, as against changing the pH and/or temperature, and enabled a selective separation of DNA fragments and humic acids. Secondly, an interval immobilization technique realized that ion-exchangeable groups could be immobilized into a cross-linked polymer matrix at a certain interval, and that the immobilized ion-exchangeable groups afforded a selective molecular recognition ability. Moreover, this technique could be applied to prepare of novel separation medium having a selective recognition ability toward a cyanobacterial toxin, cylindrospermopsin. Thirdly, the polymer based separation media prepared by a fragment imprinting technique with an alternative template molecule acted for the selective recognition of bisphenol A as one of an endocrine disruptor chemicals, and showed a capability as a practical pre-treatment medium for bisphenol A in environmental water. Furthermore, according to an evaluation for tetra-chlorinated dibenzo-p-dioxins or chlorinated bisphenol A, the compounds substituted with methyl groups instead of chlorine could be used as the alternative template molecules. Finally, the separation media for the selective recognition of microcystin variants were prepared by controlling of the micropores inside of the formed cross-linked polymer matrix with an universal moiety of microcystin variants. The prepared separation media could afford selective molecular recognition for microcystin variants. Additionally, by using together the control of micropore and functional monomers, microcystin variants could be effectively separated from other compounds.

(Received May 17, 2004)

Keywords : separation media; selective molecular recognition; interval immobilization technique; fragment imprinting technique.

Heavy metal pollution of roadside soils and dusts caused by overuse in an alpine tourist area and an analysis of the pollution behavior

Hirokazu Ozaki

Ocean Research Institute,The University of Tokyo, 1-15-1, Minamidai, Nakano-ku, Tokyo 164-8639

(Awarded by Tokyo University of Agriculture and Technology March 19, 2004)

The levels and behaviors of heavy metal pollution caused by automobiles accompanied by “overuse” were investigated in Kamikochi, Chubu Sangaku National Park, Japan. The V, Cr, Ni, Cu, Zn, As, Cd, Sb, Hg and Pb concentrations in the roadside soil and dust were generally lower in Kamikochi than Matsumoto City. In the alpine area, however, higher pollution levels were observed at the “bus terminal”, “Kama Tunnel” and “Nakanoyu”, where a high frequency of stops, start-ups and continuous idling of automobiles was observed. Seasonal changes in the total metal concentrations (especially in Cu, Zn and Sb) corresponding to the amount of traffic were observed; higher in the summer and lower in the winter. At the higher pollution level sites, the values of pH(KCl) also increased. However, the concentrations of simulated-rain-extracted and the exchangeable form and their percentages to each of the total concentration increased there as well, suggesting that heavy metals are in more labile condition. The percentages of exchangeable Ni and simulated-rain-extracted Sb to their total concentrations were significantly (p<0.05, multiple regression) related with Eh, pH(KCl), CEC, Org-C, grain size composition and total concentration of the metal. The amounts of dissolution during the survey (1998~2001) were 269 mg for Ni and 198 mg for Sb per 1 g DW sample at the bus terminal.

(Received April 9, 2004)

Keywords : overuse; heavy metal pollution; roadside dust; traffic density; outflow; accumulation.

Sensitive and precise spectrometric determination of ultra-trace elements in metals and alloys with the aid of chemical separation

Tetsuya Ashino

Institute for Materials Research, Tohoku University, 2-1-1, Katahira, Aoba-ku, Sendai-shi, Miyagi 980-8577

(Award by Tohoku University dated February 20, 2004)

Analytical procedures by using chemical separation were investigated for determination of ultra-trace elements in high-purity metals and alloys. A reductive co-precipitation method with palladium for electrothermal atomic absorption spectrometry (ET-AAS) was developed for the separation and pre-concentration of ultra trace elements. Selenium, tellurium, gold and silver could be quantitatively separated by using ascorbic acid as a reductant. Palladium acts as a carrier of co-precipitation as well as a chemical modifier in ET-AAS. Selenium or tellurium was precipitated as intermetallic compounds with palladium, but gold or silver was precipitated in each metallic state. The proposed method could also be applied to the separation of antimony, germanium and tin by using NaPH₂O₂ or NaBH₄. Removal methods of blank values were developed for determination of ultra trace carbon and sulfur by infrared absorption after combustion. A nitrogen atmosphere chamber was developed for the determination by using an electric resistance furnace. The amount of carbon on the surface and in the bulk of samples could be respectively determined and cleaning procedures of the sample surface could be investigated. In a determination using an induction-furnace method, the blank values of carbon and sulfur could be drastically reduced by heating an accelerator and a ceramic crucible for combustion. The obtained detection limits were under 0.1 µg g^-1 in all of the developed methods.

(Received April 19, 2004)

Keywords : ultra trace analysis; high-purity metals; atomic absorption spectrometry; co-precipitation; infrared absorption after combustion.

Study of the thermal-decomposition behavior and the GC/MS analytical method of polybrominated dioxins/furans and diphenyl ethers

Jun Onodera

Application & Reseach Center, JEOL Ltd., 3-1-2, Musashino, Akisima-shi, Tokyo 196-8558

(Awarded by Yokohama National University dated March 25, 2004)

It has been predicted that polybrominated dibenzo-p-dioxins (PBDDs) and polybrominated dibenzofurans (PBDFs) will cause big environmental problems in the near future, just as polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs), have already done. Therefore, the establishment of an analytical method for PBDDs/PBDFs is very important and urgently necessary. However, information regarding this matter is insufficient. In this study, the development of measurement methods and a confirmation of the thermal-decomposition behavior for PBDDs/PBDFs and polybrominated diphenylethers (PBDEs), which are brominated frame retardants (BFRs), as well as the possible cause material of PBDDs/PBDFs were pursued as parts of countermeasures to environmental pollution by PBDDs/PBDFs.

(Received June 17, 2004)

Keywords : PBDDs/PBDFs/PBDEs; HRGC/HRMS; brominated frame retardants; thermal decomposition; debromination; sensitized detection; column end cooling.

Studies on factors associated with the variations of environmental radiation dose

Koki Yamazaki

Niigata Prefectural Institute of Environmental Radiation Monitoring, 314-1, Sowa, Niigata-shi, Niigata 950-2144

(Awarded by Niigata University dated September 25, 2003)

Air-absorbed radiation doses, continuously measured around a nuclear power station, were analyzed in order to clarify the relationships between the variations of environmental radiation and the environmental factors peculiar to cold and snowy area along the coast of the Sea of Japan. First, the increase in doses was confirmed to a be derived from the precipitation originated from a high flux density of gamma-rays due to the decay products of ²²²Rn. While the decrease was attributable to the shielding effect of a part of gamma-rays, especially from 40K and 208Tl in a soil surface covered by snow layers. Second, the vertical profile of environmental doses was practically established above the ground. The mean dose rates in the winter increased unexpectedly according to a quadratic curve in the upper region. Based on the observed results, the increasing tendency can most likely be attributed to bremsstrahlung X-rays generated from thunderclouds. It was assumed that this study was the first observation of an increasing radiation dose with height associated with winter thunderstorms. Third, it became evident that the sensitivity of a radiophotoluminescence glass dosimeter decreased by about 3~5% in the winter season, when the mean temperature was relatively low, below 6.3°C. Finally, Monte Carlo calculations of terrestrial gamma-rays were carried out to simulate the observed doses above the ground.

(Received June 24, 2004)

Keywords : environmental radiation; natural radioactive nuclides; winter thunderstorm; bremsstrahlung; radiophotoluminescence glass dosimeter; Monte Carlo method; terrestrial gamma-rays.

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