BUNSEKI KAGAKU Abstracts

Vol. 55 No. 7

July, 2006

Accounts

Analysis of Associated Structures of Rhodamine B Adsorbed at Interfaces by Second Harmonic Generation Spectroscopy

Akira Yamaguchi¹, Tatsuya Uchida^1,2, Tomomi Ina¹, Kimihisa Nochi¹ and Norio Teramae¹

(Received 3 February 2006, Accepted 24 March 2006)

We have developed an apparatus for the measurement of second harmonic generation (SHG) spectra that provide direct evidence on the electronic structures of interfacial species. By applying the measurement apparatus, we have studied molecular association of rhodamine B (RB) at a heptane/water interface and trimethylchlorosilane (TMS) modified-quartz/water interfaces with a different coverage. The observed SHG spectra at the heptane/water interface showed red-shift of the peak maxima compared to the absorption maximum of monomeric RB in the bulk aqueous phase, and these spectra indicated predominant formation of in-plane associates in which the electronic transition dipoles of each monomer were arranged parallel to one another. At the TMS-modified-quartz/water interface, spectral shape of SHG spectra was almost same with that found in the heptane/water interface when the surface density of TMS was high. In contrast, with decreasing the surface density of TMS, the red-shifted peak due to the in-plane associates become weaker, and other peaks due to a sandwich dimmer appeared. We confirmed that the association form of RB depended on the surface density of TMS.

Keywords : second harmonic generation; interface; molecular association; rhodamine dye.

Research Papers

Flow Injection Determination of Trace Amounts of Manganese by Catalytic Oxidation of N-Phenyl-p-phenylenediamine with Cumenehydroperoxide

Takuji Kawashima¹, Hiroyuki Nagaoka², Masayuki Itagaki², Shigenori Nakano³ and Kunihiro Watanabe²

(Received 3 March 2006, Accepted 18 April 2006)

A sensitive catalytic method is proposed for the determination of manganese using a FIA system. The method is based on the catalytic effect of manganese(II) on the oxidation of N-phenyl-p-phenylenediamine (PPDA) in the presence of cumenehydroperoxide as an oxidant; PPDA is oxidized to a yellow compound at pH 10.5 by the oxidant, and this compound is then converted to a blue-green compound (λ_max=775 nm) with a higher absorbance than the yellow compound in a strong acidic solution. Higher sensitivity could be attained by adding triethylenetetramine (trien) as an activator. A linear calibration graph for manganese(II) was obtained over the range of 2~50 ppt and the reproducibility was satisfactory with a relative standard deviation of 1.2% for 10 ppt manganese (n=10) at a sampling rate of 27 per hour. By using cumenehydroperoxide in place of hydrogen peroxide, which was frequently used in most indicator reactions for catalytic methods based on the redox reaction, the blank values could be kept low. The proposed method was successfully applied to the determination of manganese in tap water, river water and standard river water samples.

Keywords : flow-injection determination; N-phenyl-p-phenylenediamine; catalytic method; cumenehydroperoxide; manganese; activator.

Flow Injection Fluorometric Determination of Boron in Steels with

Junichi Iwata¹, Kunihiro Watanabe¹ and Masayuki Itagaki¹

(Received 29 March 2006, Accepted 21 April 2006)

A fluorometric determination of boron in steels was investigated by a flow-injection analysis. In the determination of boron, it was found that 2,3-dihydroxynaphthalene (2,3-DHN) was excellent as a fluorometric reagent. Boron reacted with 2,3-DHN at pH 10 to form a complex; 2,3-DHN was an excess reagent. Although the height background intensity was a large problem in the determination of boron, the background fluorescence based on free 2,3-DHN could be decreased by mixing with an alkaline solution after complex formation. On the other hand, the boron-2,3-DHN complex emits strong fluorescence in an alkaline solution. For the determination of a trace amount of boron in steels, the on-line separation/preconcentration of boron from iron matrix was performed by using resin (IRA743). The boron was preconcentrated using a flow rate of 13 ml/min at pH 5.7 in the sample solution. Iron as a matrix ion interfered with the determination of boron. Therefore, the iron ion was masked with 0.1 M EDTA in advance before the preconcentration of boron with IRA743. However, the EDTA interfered with the adsorption of boron on the resin. The problem was solved by decreasing the flow rate from 13 ml/min to 2.1 ml/min. As a result, the sample solution volume was decreased from 65 ml to 10.5 ml at 5 min concentration. The boron-2,3-DHN complex in aqueous solution was detected by measuring the fluorescence intensities (λ_ex=300 nm, λ_em=340 nm). The calibration curve for boron constructed by 5 min concentration was linear over the range of 0 to 40 ppb. The limits of detection and determination for boron were 0.3 and 0.9 ppb, respectively. The relative standard deviation at 20 ppb B was 2.6% (n=6). The limit of detection was 0.04 ppb in case of 80 min concentration. The determination results for boron in standard steel materials showed good agreements with the certified values.

Keywords : boron; steel; flow injection analysis; preconcentration; fluorometry; 2,3-dihydroxynaphthalene.

Determination of Polybrominated Diphenylether in Polystyrene Resin by Gas Chromatography/Inductively Coupled Plasma Mass Spectrometry

Tetsuya Nakazato¹, Mikio Akasaka^1,2, Ramaswamy Babu Rajendran³ and Hiroaki Tao¹

(Received 27 February 2006, Accepted 2 May 2006)

The analytical performance of gas chromatography/inductively coupled plasma mass spectrometry (GC/ICP-MS) was evaluated for the determination of polybrominated diphenylether (PBDE) including deca BDE (BDE-209). The detection limits ranged from 0.086 pg (BDE-85) to 19 pg (BDE-209), which were 1 or 2 orders of magnitude superior to those with GC/electron impact ionization-low resolution mass spectrometry and GC-ECD. The present method gave the same sensitivity for thermally stable PBDE isomers from tri- to hepta-BDE, and the same calibration graph could be used to quantify these isomers. On the contrary, a non-linear calibration graph, different sensitivity and worse detection limits were observed for thermally labile isomers from octa- to deca-BDE, but these problems originated not from ICP-MS but from GC; that is, the decomposition in the GC column and the injection port turned out to be an essential problem that must be resolved. PBDE, including BDE-209, in polystyrene resin was successfully determined by the present method using on-column injection. Since the spectral interface from co-existing materials was almost negligible, and therefore clean-up was unnecessary in the sample-preparation step, the present method was superior in robustness and rapidness to other conventional methods.

Keywords : GC/ICP-MS; brominated flame retardants; PBDE; plastics; RoHS.

Technical Papers

Congener-Specific Determination of Brominated/Chlorinated Dioxins and Related Compounds by Two-Dimensional HPLC Cleanup System

Nobuyasu Hanari^1,2, Yuichi Miyake¹, Yuichi Horii¹, Tsuyoshi Okazawa¹ and Nobuyoshi Yamashita¹

(Received 17 January 2006, Accepted 31 March 2006)

The method enables congener-specific determination not only of polychlorinated dioxins but also of polybrominated diphenyl ethers (PBDEs), -biphenyls (PBBs), -dibenzo-p-dioxins (PBDDs) and -dibenzofurans (PBDFs) using two dimensional high performance liquid chromatograph (HPLC) with graphitized carbon and pyrenyl silica columns cleanup, and high resolution gas chromatograph with high resolution mass spectrometry (HRGC/HRMS) system. Additionally, the analytical method developed enables separation and quantification not only of PBDFs without co-elution from PBDEs but also of PBDE IUPAC No. 209. The reliable analysis of PBDE-209 was operated in parallel by the HRGC/HRMS and GC with tandem mass spectrometry, because the quantitative analysis of PBDE-209 is relatively difficult task due to liable physical properties and high molecular weight. Calibration curves from the peak areas of PBDEs, PBBs and PBDDs/DFs were linear with high correlation coefficients of more than 0.992 at the range from 2 to 1000 pg/ml (some congeners: 10 to 1000 pg/ml). The relative standard deviations of PBDEs, PBBs and PBDDs/DFs by the peak areas were acceptable with a range of 2.7 to 11.2%, 2.0 to 11.7% and 5.9 to 12.5%, respectively. This analytical method could be applied to various matrices on pine needles as passive indicator and fly ash of international calibration study. Congener-specific determination of PBDEs, PBBs and PBDDs/DFs in pine needles was achieved in this study for the first time. Risk assessment by congener-specific data of brominated/chlorinated dioxins and related compounds was possible to carry out using this developed method.

Keywords : polybrominated diphenyl ethers; polybrominated biphenyls; polybrominated dibenzo-p-dioxins; polybrominated dibenzofurans; polychlorinated dioxins; congener-specific determination.

Analytical Reports

Plastic Certified Reference Materials JSAC 0611~0615 for Determination of Hazardous Constituents Using X-Ray Fluorescent Analysis

Kazuhiko Nakano¹, Toshihiro Nakamura¹, Izumi Nakai¹, Akira Kawase¹, Makoto Imai¹, Mikio Hasegawa¹, Yohichi Ishibashi¹, Isamu Inamoto¹, Kazufuyu Sudou¹, Masaru Kozaki¹, Akira Turuta¹, Hisashi Honma¹, Akihiro Ono¹, Kazutoshi Kakita¹ and Mamoru Sakata¹

(Received 25 January 2006, Accepted 28 March 2006)

The Japan Society for Analytical Chemistry has developed a series of certified reference materials (CRMs) for X-ray fluorescence analysis of hazardous elements (Pb, Cd, Cr) in plastics. These CRMs (named as JSAC 0611~0615) were prepared by the casting of polyester including a toluene solution of organometallic compounds as a standard. The prepared disk had a homogeneous elemental distribution and excellent durability. Concentrations of the three trace elements were ranged from 0 to 200 mg/kg for Pb, 0 to 50 mg/kg for Cd, and 0 to 200 mg/kg for Cr. An interlaboratory study was performed by 21 laboratory's participants. The z-scores in robust method were applied to statistical analysis. The certified uncertainties were determinant in the confidence levels of 95%. These presented CRMs are expected to be useful for the screening analysis and the precise analysis of hazardous elements in plastics.

Keywords : plastics; certified reference materials; hazardous elements (Pb, Cd, Cr); X-ray fluorescent analysis.

Soil Certified Reference Materials JSAC 0402 and JSAC 0403 for Determination of Inorganic Components

Yo-ichi Ishibashi¹, Shin-ichi Yamasaki¹, Shozo Asada¹, Akira Okada¹, Masashi Murakami¹, Aki Hamamoto¹, Akihiro Ono¹, Kazutoshi Kakita¹ and Mamoru Sakata¹

(Received 14 February 2006, Accepted 17 April 2006)

The Japan Society for Analytical Chemistry has developed two new certified reference materials, (CRMs) JSAC 0402 and JSAC 0403, for analyses of trace inorganic components. The materials were certified for the concentrations of 13 elements (Cd, Pb, As, Cr, Se, Cu, Zn Ni, Mn, V, Hg, B and F) and for the concentrations obtained by the elution analysis (issued by Ministry of Environment) of 7 elements (Cd, Pb, Hg, As, Se, F and B). For certifying analytical data, an interlaboratory comparison exercise, in which 17 laboratories had participated, was carried out. In a statistical analysis of data that reported from participants, z scores in the robust method were applied to reject outliers, followed by the usual statistical procedure. The presented CRMs are expected to be useful for the quality assurance and the quality control in the analysis of inorganic pollutants in soil.

Keywords : soil; inorganic pollutants; interlaboratory comparison exercise; certified reference material; elution analysis.

Immunoassay Screening Method for Polychlorinated Biphenyls in Transformer Oil

Naoya Ohmura¹, Thomas R. Glass¹, Kazuhiro Sasaki¹, Takashi Joh², Yukihiro Taemi², Katsuya Imanishi³ and Shingo Terakado⁴

(Received 20 March 2006, Accepted 28 April 2006)

We described here the results of measuring the PCB levels in eleven hundred transformer oil samples using an immunoassay screening method. Five hundred samples out of the total were remeasured using a GPC/GC/ECD method. A comparison of these results on ROC (receiver operating characteristic) plots showed that the immunoassay provides a useful screening method. In the case that the regulatory concentration of the total PCB was set at 0.5 mg/kg, the most suitable cutoff concentration for the immunoassay for screening was calculated to be at 0.4 mg/kg with false negative and false positive rates of zero and seven percent, respectively.

Keywords : PCB; immunoassay; transformer oil; screening.

Short Communication

Development of Visual Colorimetry for Formaldehyde in Water Based on Membrane Filtration and Its Application to Tap Water

Shigeru Taguchi¹, Eriko Seki¹, Keita Murai¹, Noriko Hata¹ and Hideki Kuramitz¹

(Received 24 April 2006, Accepted 29 May 2006)

A simple, rapid and low-cost method for the visual determination of formaldehyde in water based on the retention of two ion-associates on a membrane filter is proposed. Formaldehyde in water was reacted with 3-methyl-2-benzothiazolionone hydorazone (MBTH) to form an azine. The remaining MBTH was oxidized by ferric ion to form a light-yellow cation. The cation was reacted with the azine to form a deep-blue cation. Both blue and yellow cations were reacted with tetraphenylborate anion to form blue and yellow hydrophobic ion-associates, respectively. The ion-associates were retained on a membrane filter by filtration. The color of the filter was changed from yellow, green to blue, depending on the concentration of formaldehyde. The concentration was easily determined by comparing the color with those obtained from a series of standard solutions of formaldehyde. The formaldehyde from 0 to 0.07 ppm in water was determined with error less than ±0.01 ppm. Thirty minutes was enough for the entire analytical procedure. This method was successfully applied to tap-water samples spiked with formaldehyde. It will be useful for rapid judgment of a water sample to pass the quality standard for drinking water in Japan.

Keywords : formaldehyde in water; visual method; membrane filter; colorimetry; tap water.

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