BUNSEKI KAGAKU Abstracts

Isotope dilution inductively coupled plasma mass spectrometry (ID-ICP-MS) is one of the reliable methods for total and species-specific quantitative analysis of trace elements. However, several technical problems (e.g. spectral interference caused from sample constituents) should be overcome to obtain reliable analytical results when environmental samples are analyzed by ID-ICP-MS. In our laboratory, various methods based on ID-ICP-MS have been investigated for reliable quantitative analyses of trace elements in environmental samples. In this paper, coprecipitate separation/ID-ICP-MS for the determination of trace elements in sediment, cation exchange disk filtration/ID-ICP-MS for the determination of selenium in sediment, species-specific ID-ICP-MS using ¹¹⁸Sn-labeled organotin compounds for the determination of butyltins and phenyltins, and the application of the ID-ICP-MS methods to the certification of sediment reference materials are described.

There is a possibility that an accuracy determination of arsenic is difficult in the case of some existing kinds of chemical compounds in environmental samples due to a sensitivity difference depending on the chemical compounds. To discuss the phenomenon and the sensitivity difference between chemical compounds, the mechanism and behavior of a sensitivity difference between arsenic compounds with inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma optical emission spectrometry (ICP-OES) and more instruments were investigated. The calibration solutions of As(III) and As(V) were gravimetrically prepared from a unique mother standard solution of a JCSS As standard solution, which is certified by Japan Calibration Service System (JCSS). The arsenobetaine was prepared from the certified reference material of a BCR 626 arsenobetaine solution, which is certified by IRMM. In the case of ICP-MS and ICP-OES analyses, internal standard elements were added, and they were monitored together with arsenic. Although there was no sensitivity difference between As(III) and As(V) with atomic absorption spectrometry (AAS), graphite furnace atomic absorption spectrometry (GFAAS), X-ray fluorescence (XRF), and neutron activation analysis (NAA), the As(V) was found to be 4% more sensitive than the As(III) with ICP-MS and ICP-OES. Also, it was concluded that the mechanisms of this sensitivity difference between them were investigated by ICP-MS and ICP-OES, and it was elucidated that the formation rates of hydride polyatomic species of As were definitively different between As(III) and As(V) species in the plasma.

To elucidate the uptake mechanism of pollutants for up-slope and radiation fog, we collected up-slope fog and particulate matter (PM) at the Akita Hachimantai mountain range and radiation fog at Takanosu basin in northern Japan. For up-slope fog, it was found that the fog generated in the westerly wind was mainly polluted by cloud condensation nuclei (CCN), but that generated in the easterly and/or southerly wind was polluted by sea-salts and gaseous NH₃ during residense after the activation of CCN. Yamase’s fog was polluted by gaseous NH₃ and sea-salt after the activation of CCN, but the pollution degree of Yamase (E) was the lowest of four wind-directions categories (N, E, S, W) and the pH was the highest. Radiation fog was polluted not only by an acidification component, but also gaseous NH₃ after the activation of CCN, and thus radiation fog was neutralized and the pH was the highest.

In this study, polychlorinated biphenyls (PCB) in ambient air samples collected in 2002〜2006 in Nagasaki Prefecture, Japan were determined by using a high-resolution gas chromatography-high resolution mass spectrometry. Seasonal changes of the concentration and TEQ values of PCB at 8 areas (A〜H) involving 3 isolated island (F〜H) areas were examined. The concentration of PCB in the summer in the range of 137〜416 pg/m³ was higher than that in the winter in the range of 67〜126 pg/m³ (p＜0.01). The isolated islands showed a two or three-times higher concentration of PCB compared to the districted areas (p＜0.01). Furthermore, to identify the source of PCB, a principal component analysis (PCA) and a chemical mass balance (CMB) method were applied. In isolated island areas, Kanechlor KC300 was a major source throughout the year, whereas Kanechlor KC400 in summer and the products by combustion in winter were found to be major sources in districted areas.

Most of environmental organic chemicals generally have chloride in their structure. Therefore, we should research the chlorination mechanism of carbon. Most dioxins are concentrated in collected fly ash at post-combustion zone during the process of a municipal solid waste incinerator. In this paper, we report on the application of the Cl-K near-edge X-ray absorption fine structure (NEXAFS) in order to understand the chlorination mechanism of carbon in fly ash. It has been revealed that the separation of the chloride form bonded with organic carbon (C-Cl) was easy due to a peak of the Cl-K NEXAFS spectrum. A chlorination effect can be estimated by using Cl-K NEXAFS without depending on metal species. An analysis of the Cl-K NEXAFS spectrum showed a reduction of copper(II) chloride at 300°C and the oxidation of iron(III) chloride at 400°C, related to chlorination process of carbon.

Dissolved organic matter (DOM) in a water sample from Lake Biwa was fractionated with a nonionic resin (DAX-8) into hydrophilic DOM (Hi), hydrophobic acids (HoA) and hydrophobic neutral DOM (HoN). The vertical distribution and seasonal changes of DOM and its fractions were evaluated. The concentrations of DOM, HoA and Hi in surface water samples from Lake Biwa tended to be high in the summer and low in the winter. In the summer, the concentrations of DOM, HoA and Hi varied greatly in the lake thermocline (depth 10〜20 m). The increase in the concentrations of DOM, HoA and Hi in Lake Biwa during the warm season may be attributed to algal DOM. The trihalomethane (THM) formation potential of water samples collected from Lake Biwa was high at a depth of 10 m and 35〜40 μg L⁻¹ at depths lower than 20 m. The THM formation potential per organic carbon unit of algal DOM was larger than that of soil humic substances, and its order was as follows : Microcystis aeruginosa＞Cryptomonas ovata＞Staurastrum dorcidentiferum.

The determinations of trace perchlorate in environmental samples by suppressor ion chromatography with an online preconcentration technique is reported. Each sample was preconcentrated, and less strongly held anions preeluted before the analyte was transferred to the principal separation system. The low limit of detection (S/N＝3) was 0.16 μg L⁻¹ for a 5 mL water sample, and about 200 times without the preconcentration being improved. This method was applied to the determination of perchlorate in rainwater and atmospheric aerosol, and the behavior and origin of perchlorate in the environment were investigated. The perchlorate concentration in rainwater had a level of N.D.〜3.53 μg L⁻¹. The seasonal variation of perchlorate in atmospheric aerosol, 0.07〜9.64 ng m⁻³, showed a high level in the spring and a low level in the summer. When the perchlorate concentration in aerosol was high, pollutants containing perchlorate may be transported from China to Japan by backward trajectory analysis.

X-ray fluorescence analyses of 12 major and 6 minor components in alkali-washed fly ash of municipal solid waste were developed using a powder briquette method. Fly-ash samples were ground for 80 min using a ball mill to prepare reproducible powder briquettes, when the resultant particles had a 12 μm modal diameter and gave good reproducibility (3.2%). The mixture of reagents was ground for 20 min by a ball mill after 80 min of mixing with a V-type mixing machine or 2 h of manual mixing using an alumina mortar. The calibration curves for 12 major components and 6 minor elements showed good linearity. About 1.1 g of a sample was packed into a polyvinyl ring (18 mm inside diameter ; 21 mm outside diameter ; 7 mm thickness) and pressed by pressure at 19.6 MPa for 1 min using a hand press. For the determination of Cl and Br, tube power was used under 1.0 kW (50 kV - 20 mA). The quantitative results of the main components showed good agreement with certified values of a coal fly ash standard reference material (NIST 1633b). The proposed method was applied to 18 components in fly ash. Fly ash of A and B mainly consisted of Al₂O₃, SiO₂, Cl, and CaO. Fly ash of C consisted of Na₂O, SO₄, Cl and K₂O. Several thousand parts per million of Zn and Pb were contained in all fly-ash samples.

In the present study, trace metals in coastal surface seawater around Okinawa were determined by inductively coupled plasma mass spectrometry (ICP-MS) with chelating disk preconcentration. As a result, the concentrations of V, Mn, Co, Ni, Cu, Zn, Mo, Cd, Pb, and U were obtained in the range from 10 μg L⁻¹ to 0.001 μg L⁻¹ for 6 samples. In addition, multielement profiling analyses were carried out using analytical values obtained in order to elucidate the features of trace metals in each coastal sea area. For coastal surface seawater near an urban area, the analytical values for Zn, Cu, Mn, and Pb were higher by more than 10-fold the literature values for open-surface seawater, and those of Cd were also relatively high. Such a trend concerning the multielement profile was almost similar to the literature values for coastal seawater of the main island of Japan. On the other hand, the analytical values of most elements for coastal surface seawater near a suburb area were in the range from 0.5 to 5 fold, compared to the literature values for open surface seawater. From multielement profiling analyses for nutrient type elements in marine chemistry, it was suggested that the concentrations of Zn and Cd in a coral sea area normalized to literature values for open surface-seawater were higher than those of Ni and Cu.

A method for specimen collection by using a synthetic resin adhesive is proposed as a new sampling method for monitoring of heavy-metal deposits on tree bark. The resin adhesive was applied to tree bark of Zelkova serrata (Keyaki in Japanese name) at 160 cm high from the ground. An adhesive sample was peeled from the bark after hardening, and subjected to ICP-MS analysis. It was found that V, Zn, Cd, Sb, W, Pb were efficiently collected by the resin from the bark. This sampling method was applied to the monitoring of heavy-metal pollution at 6 points, including urban, suburban, and rustic region of the Kanto region of Japan. The concentrations of V, Cu, Zn, Cd, Sb, W and Pb in the samples at an urban site were more than 10-times higher (e.g. Pb 1920 ng cm⁻²) than those at a rural site (e.g. Pb 153 ng cm⁻²). This sampling method is simple, quick and causes less damage to the trees against sampling. Consequently, it will be useful for widespread and high-density environmental monitoring of heavy-metal pollutants.

The whole-body concentrations of heavy metals (Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Cd, and Pb) in caddisfly (Stenopsyche marmorata) larvae from the Watarase and Kiryu Rivers were determined by atomic absorption spectrometry and instrumental neutron activation analysis to evaluate the usefulness of this insect as a bioindicator for assessing heavy metal pollution in river water. An abandoned large copper mining complex was located about 30〜40 km upstream of the sampling site of caddisfly larvae in the Watarase River. The caddisfly larvae in the Watarase River enrich heavy metals, as compared with those in the Kiryu River, presumably on account of the influence of the copper mine. The concentrations of heavy metals in the caddisfly larvae of both rivers are higher in the summer than in the winter. The caddisfly larvae of the Watarase River, however, significantly fluctuate its concentrations of heavy metals month by month, even in the summer season. A careful examination of the concentrations of heavy metals in caddisfly larvae is thus necessary to assess the environmental pollution of these metals in the river system. The concentrations of heavy metals in caddisfly larvae of the Kiryu River in the winter season (from December to February) are similar to those in caddisfly larvae of non-polluted rivers. The background concentrations of Cu and Zn in caddisfly are estimated to be 20〜30 μg g⁻¹ and ca. 100 μg g⁻¹, respectively.

An automated column chromatography system has been developed in order to achieve a clean-up procedure for the determination of carcinogenic polycyclic aromatic hydrocarbons more conveniently. The system can hold 8 solid-phase extraction columns, and the elution volume of solvents can be controlled in 1 μL of resolution. The recovery of PAHs obtained by using the automated chromatography system matched with that using the manual chromatography procedure. The high-temperature Soxhlet extraction/automated column chromatography/HPLC/fluorescence detection method developed in this study has been applied to the determination of PAHs in aerosol collected in Beijing, China. ΣPAHs, which is the sum of the concentrations of 15 PAHs measured in this study, were 198.5±149.8 ng m⁻³ (n＝24) in the heating season, and 50.1±63.7 ng m⁻³ (n＝51) in the non-heating season. The strong seasonal variation is probably due to coal combustion for residential heating in winter season.

A practical way to reduce the matrix effect and to solve the column clogging problem in environmental surface water analysis with liquid chromatography-mass spectrometry (LC/MS) has been proposed. In LC/MS analysis of surface-water samples, a matrix effect caused by complex matrices is one of the most serious impediments to improving the reliability of quantitative determinations. An internal calibration method with deuterated compounds provides improved reliability, while it is still hardly a sufficient solution. Moreover, due to the smaller diameter of an analytical column for LC/MS, the column clogging problem is another practical difficulty as well. We found it possible to solve these problems by employing column switching LC/MS, which consists of a pretreatment column containing surface modified polymer particles and three flow change-over valves for cleaning any remaining matrices in the pretreatment column. The matrix effect observed in surface-water analysis is often caused by humic compounds, which are negatively charged under a neutral pH condition. These compounds can be removed prior to LC/MS analysis with the repulsive force generated by sulfonic groups immobilized on the surface of the pretreatment column packing. The column clogging problem is normally caused by fine substances existing in water samples. A 3-valve column switching system can wash the pretreatment column and the flow line with clean water after pre-concentration to remove remaining actual water sample. This 3-valve LC/MS system was applied to actual LC/MS determinations of bisphenol A and 17β-etradiol. The detection limit in an actual sample is less then 1 ng L⁻¹ for both of the target compounds. The repeatability was less than 2% at 10 ng mL⁻¹ (n＝5), the recovery was more than 91% and linearity as the square of coefficient of correlation was more than 0.9999. A particular pressure increase was not observed through one hundred of repeated analyses of actual river-water samples.

A commercial organoborane compound, pyridine-triphenylborane (PTPB), is often applied to ship hulls as an anti-fouling agent in order to keep them free from marine organisms, such as barnacles and bivalves. However, the degradation process of PTPB and its degradation products have not been well understood, because of lack of an analytical method for both PTPB and its estimated degradation products. We previously developed a procedure using capillary zone electrophoresis (CZE) with direct UV detection for the simultaneous determination of PTPB and its estimated degradation products, such as diphenylborinic acid (DPB), phenylboronic acid (MPB), and phenol. For this study, simple degradation experiments were carried out to verify the usefulness of the proposed method for further PTPB degradation investigations. That is to say, PTPB samples dissolved in acetonitrile were put in the open air and a dark place to examine the effects of the light intensity and the temperature on the degradation of PTPB. The sample solutions were analyzed by the CZE method with the elapse of time. As a result, it was suggested that the degradation of PTPB was significantly affected by the light intensity, rather than the temperature. It has consequently been demonstrated that the CZE method is a useful tool to elucidate the degradation process of PTPB and its degradation products.

The simultaneous determination of orthophosphate and silicate ions in river water was examined using ion-exclusion chromatography with spectrophotometric detection at 680 nm after derivatization with molybdate and malachite green. In this study, optimization of the color-forming reactant composition to form the ion association complex of heteropolyacids with malachite green was examined. The optimum concentration of ethanol (30%) in the reactant accelerated the formation of the ion-association complex, resulting in high sensitivity for the detection of ions. Using the optimized reactant containing 100 mM H₂SO₄/10 mM Na₂MoO₄/0.05 mM malachite green/30% ethanol, the calibration curve of orthophosphate and silicate ions was linear in the range of 0〜200 μg L⁻¹ as P and 0〜2000 μg L⁻¹ as Si with a good correlation coefficient of 0.998. The relative standard deviations of the peak areas and the retention time of orthophosphate and silicate ions were between 0.5 and 3.2% for five repeated measurements. The detection limits of orthophosphate and silicate ions were 0.3 and 2.5 μg L⁻¹, respectively. The detection limit for the orthophosphate ion was 5 to 10-times improved when compared with those of previous studies using molybdenum-yellow or molybdenum-blue as a derivatization with molybdate. The recovery tests using river water for orthophosphate and silicate ions were 97.2% and 102.5%, respectively. The developed method was successfully applied to the simultaneous determination of orthophosphate and silicate ions in practical river-water samples.

Electrostatic ion chromatography (EIC) of anions and cations with water eluent has been investigated for the development of water-monitoring systems in developing countries, which have the nature of simple, lower running cost, and non-chemical waste. For selecting the separation column, sulfobetaine-type zwitterionic surfactant (CHAPS)-modified silica C₁₈ and silica C₃₀ columns, and a zwitterionic stationary phased column HILIC were compared for anion separations. The retention order of the analyte anions was SO₄²⁻＜Cl⁻＜NO₃⁻＜I⁻＜ClO₄⁻ without regard to the types of the columns, depending on the nature of EIC separation. However, the resolutions were different, because the anion separations by EIC were strongly affected by the hydrophobicity of the stationary phase. As a result, the CHAPS-modified silica C₁₈ column was the most suitable as a separation column in EIC in terms of the peak resolution and the retention time. In contrast, cation separations using the CHAPS-modified silica C₁₈ column with a water eluent were in the order of monovalent cations (Li^＋, Na^＋, K^＋ and NH₄^＋) ＜ divalent cations (Mg^2＋ and Ca^2＋). This fact means that the sulfobetain-type zwitterionic stationary phase has much higher selectivity for anions than for cations. Moreover, a pre-column (cation-exchange resin in the Li^＋-form for anion separations, and anion-exchange resin in the Cl⁻-form for cation separations) was connected in tandem before the separation column, in order to make uniform the counter ion for analyte ions and to apply this method to real water samples. Under the optimized conditions, the linearity of the calibration graph, the detection limit, and the reproducibility for the common anions were tested, and satisfactory results was obtained for all common anions. The potentiality of EIC was demonstrated in practical applications to the determination of common anions (SO₄²⁻, Cl⁻, NO₃⁻ and HCO₃⁻) and hardness in river water.

A simple spectrophotometric method has been developed for the determination of dissolved oxygen in environmental water samples. This method is based on red-brown color development of manganese(III) dissolved from manganese(III) hydroxide, which was oxidized with dissolved oxygen from manganese(II) hydroxide precipitated in an aqueous solution ; the amount of the oxidized manganese(III) hydroxide was equivalent to that of dissolved oxygen in the solution. To a water sample, which was taken into a graduated syringe, a manganese(II) sulfate solution and a sodium hydroxide solution were added to form a manganese(III) hydroxide precipitate, and then the precipitate in the water sample was dissolved with sulfuric acid. The color intensity due to dissolved manganese(III) was proportional to the concentration of dissolved oxygen. Up to 14 mg L⁻¹ of dissolved oxygen could be determined spectrophotometrically at 490 nm with a relative standard deviation of 1.1%. The established method was successfully applicable to environmental water, such as river and lake water samples.

Hexavalent {Cr(VI)} and trivalent chromium {Cr(III)} in environmental materials such as soil and plastics were investigated using a laboratory X-ray absorption fine structure (XAFS) spectrometer equipped a W anode X-ray tube. The Cr-K X-ray absorption edges were observed on the XANES spectra of soil (total chromium 606 ppm) and plastic (213 ppm) samples with a fluorescence mode, while the signal-to-noise (SN) ratios of these spectra were too low to determine the height of pre-edge peak of Cr(VI) and the value of the energy on the Cr-K X-ray absorption edge. The XANES spectra of reference samples prepared by Cr₂O₃ {Cr(III)} and CrO₃ {Cr(VI)} particle reagents were also recorded with the transmission mode. In order to improve the SN ratios of XANES spectra, a smoothing treatment by Savitzky-Golay method was applied to the XANES spectra of the soil and plastic samples. By the smoothing treatment, SN ratios of these spectra were improved, though the height of pre-edge peak on the XANES spectra of Cr(VI) reference sample had decreased less than 5%. The height of pre-edge peak and the value of the energy on the Cr-K X-ray absorption edge of soil and plastic samples were given by smoothed XANES spectra. Using the height of pre-edge peak and the value of the energy on the Cr-K X-ray absorption edge of reference samples, the ratios of Cr(VI)/Cr(III) on the soil and plastic samples were calculated.

In order to elucidate the mechanism of the purification system in the Yatsu tideland, we have analyzed sediments of the Yatsu tideland and the Shibaura canal by instrumental neutron activation analysis (INAA) and ⁵⁷Fe Mössbauer spectroscopy. In addition, we have examined the distribution and behavior of Fe in pore water by several analytical methods, such as ICP-AES, capillary electrophoresis (CE) and Absorption Spectrophotometry. We defined a purification system in which metals are fixed as stable forms, like sulfide into the sediments. The vertical distribution of Fe in pore water observed by ICP-AES showed a feature complementary to that of pyrite in all core samples. This suggests that Fe dissolved into pore water from the sediments was consumed for pyrite formation. The same concentration to the prepared solution was observed for Fe^2＋, while the concentration of Fe^3＋ was detected only at 1〜4% of that for the prepared solution by CE. We thus concluded that Fe^3＋ is the dominant species in pore water. Moreover, Fe^3＋ makes a variety of chelate complexes with something that is assumed to be organic matter. Normally, Fe^3＋ could be soluble in pore water by combining with chelating agents, and solved Fe^3＋ should be consumed to form pyrite. Therefore, we could explain why the Yatsu tideland shows a “high potential of purification system”. Furthermore, our results imply that the Fe chelate complexes in the Yatsu tideland could be a source of Fe supply to the ocean, and help to solve the sea desert problem. On the whole, pore water plays not only a key part in a purification system, but also an important part in the ocean.

Altitudinal differences, seasonal and annual changes in the soil pH and chemical compositions were investigated using soil samples collected from Mt. Hiei between 2000 and 2004. The mean values of the soil pH were pH 3.5〜4.0 at altitudes of around 350 m and 550〜650 m, and the molar ratios of BC/Al were also low. However, the concentrations of sulfate and chloride ions were high. The values of the soil pH in 1994 were lower than those in 2000. The difference in the soil pH with the altitude of Mt. Hiei in 1994 was especially big. The BC/Al ratios in 2000 were lower than those in 1994. A decline in the BC/Al ratios was also observed at Mt. Ogura, Mt. Kinugasa and Mt. Daimonji from 1992 to 2000. A decline in the buffering capacities of soils from mountains in Kyoto City may be due to acid deposition.