BUNSEKI KAGAKU Abstracts

Vol. 55 No. 5

May, 2006

Accounts

Study on Water Quality Monitoring by Advanced Ion-Exclusion Chromatography

Kazuhiko Tanaka^1,2,3

(Received 12 September 2005, Accepted 18 March 2006)

Several advanced ion-exclusion chromatographic (IEC) methods for the determination of anions (sulfate, nitrate, and chloride ions), cations (sodium, ammonium, potassium, magnesium, and calcium ions), HCO₃^-, PO₄^3-, and H₃SiO₄^- were studied. The goal was to evaluate the environmental water quality of several locations using polymethacrylate-based ion-exchange resin columns and different types of eluents. Separation science was studied regarding a multifunctional separation mechanism based on ion-exclusion, cation-exchange, adsorption, simultaneous ion-exclusion/cation-exchange, and vacant ion-exclusion using IEC methods. They were applied to weakly acidic cation-exchange resin and weakly basic anion-exchange resin columns. Anions, cations, amines, carboxylic acids, and non-ionic substances are considered to be important for evaluating water quality. As a result, a high-speed simultaneous determination of anions and cations was achieved in a 5 min. when applying IEC with conductivity detection on a weakly acidic cation-exchange resin column by elution with tartaric acid-18-crown-6-water. Selective and highly sensitive IEC determination of HCO₃^- from strong acid anions was achieved when using a water eluent and enhanced conductivity detection. A selective, highly sensitive, and simultaneous determination of PO₄^3- and H₃SiO₄^- was achieved when using the water eluent and UV-detection at 370 nm. A highly sensitive and selective determination of ammonium ion from mono- and divalent cations was achieved when using IEC with the enhanced conductivity detection on a weakly basic anion-exchange resin column by elution with water. The effectiveness for these IEC methods was demonstrated in the applications to an environmental water quality monitoring of rain, river, and sea water. A performance evaluation was also conducted for a photocatalyst, such as titania to some organic, inorganic, and non-ionic substances.

Keywords : ion-exclusion chromatography; ion-exchange resins; anions; cations; carboxylic acids; amines; water quality monitoring; environmental waters; photocatalyst.

Research Papers

Cyclic Flow Injection Chemiluminescent Analysis of Fe(III) with 1,10-Phenanthroline Using an On-Line Concentration Method

Kunihiro Watanabe¹, Yasuchika Ishii¹ and Masayuki Itagaki¹

(Received 31 January 2006, Accepted 9 March 2006)

A circulatory flow injection method (cyclic FIA) for the repetitive determination of Fe(III) was studied. Fe(III) was determined by a chemiluminescent measurement using 1,10-phenanthroline in the presence of hydrogen peroxide. The best pH for a chemiluminescent reaction on the analysis of Fe(III) was proposed to be 9.8 by the conventional method. However, the pH for cyclic chemiluminescent determination of Fe(III) was varied to 7 as the best pH, because the base line as a background signal increased with a continuous determination at pH 9.8. As a result, the sensitivity of Fe(III) determination by the chemiluminescent method decreased remarkably compared to that of the conventional method. Therefor, the concentration method was investigated by on-line solid extraction using a Teflon capillary tube. Cyclic FIA developed by a single on-line flow system involves another line for concentration of Fe(III) in the sample solution for 5 min. After the concentration of Fe(III) inside the capillary tube, the Fe(III) was eluted on-line with a small amount of ethanol in the carrier line. The carrier solution as a reagent -waste in a reservoir was composed of Fe(III),1,10-phenanthroline, hydrogen peroxide, Zephiramine (caionic surfactant) and tris (pH buffer agent). The Fe(III) reacted with the carrier solution in a chemiluminescent spiral cell under control of the temperature. The background signal by 100-times repetition-determination for Fe(III) was stable using ethanol as an elute solution. The limit of the determination for Fe(III) was 0.1 ppb under the optimum conditions, i.e., pH 8 for the concentration, 5 min as the concentration time, 5 m as the concentration capillary tube length, 100 ml for the volume of the elute solution, a sample flow rate of 2.8 ml/min, 0.075 M Zephiramin, and 20% hydrogen peroxide. A linear relationship between the concentration of Fe(III) and the observed chemiluminescent intensity was obtained over the range of 0.3~100 ppb. The results of a trace iron determination for tap water showed a good agreement with the values obtained by ICP-AES.

Keywords : cyclic flow injection analysis; Fe(III); 1,10-phenanthroline; concentration; chemiluminescence.

Technical Papers

Acid Dissociation Constants of 2-Substituted-8-Quinolinols and the Complexing Properties

Jun-I-chi Tanaka¹, Yoshitaka Masuda² and Akio Yoneda³

(Received 25 July 2005, Accepted 16 March 2006)

A series of 2-substituted-8-quinolinols possessing active methin carbon at the terminal of a chain was prepared. The dissociation constants and the chelate formation constants with copper(II), cobalt(II), nickel(II), zinc(II) and cadmium(II) were measured spectrophotometrically in 50% v/v aqueous dioxane at 25°C±0.1°C. As reflection of the electron withdrawing substituents, the pKa1 values of these ligands were smaller than that of 8-quinolinol, especially in the case of cyano substituents. The complexes revealed a 2 : 1 ligand-to-metal ratio. The values and order of the formation constants (log k_f) of Cu>Zn>Ni>Co>Cd>at ligand connecting ethylester skubstituents were approximately the same as that of 2-methyl-8-quinolinol. This paper discusses the third donor properties of a carbon atom bonded to active hydrogen, which was reported as a C, N, O-tridentate ligand upon cyclometalation with soft metals.

Keywords : 2-substituted-8-quinolinols; C-donor properties; divalent metal ion; acid dissociation constant; formation constant.

Simple and Rapid Chemiluminescence Assay for Lipase Activity in Pharmaceutical Preparations Using Proenhancer Substrate

Kimiyo Arima¹, Tomoko Ichibangase¹, Yoshihito Ohba¹, Naoya Kishikawa¹ and Naotaka Kuroda¹

(Received 13 February 2006, Accepted 23 March 2006)

A novel chemiluminescence (CL) assay method, using a HDI-laurate [lauric acid ester of 2-(4-hydroxyphenyl)-4,5-diphenylimidazole (HDI)] as a proenhancer substrate, was applied to the determination of lipase (triglycerol lipase, EC 3.1.1.3) activity in pharmaceutical preparations. The method is based on an enhanced CL reaction of luminol-horseradish peroxidase (HRP)-hydrogen peroxide with HDI, which is liberated from the proenhancer substrate by enzymatic hydrolysis. The proposed method involves a homogeneous reaction system in which enzymatic hydrolysis of HDI-laurate and enhanced CL reaction with HDI occur in the same reaction mixture. The lipase activities of three commercially available preparations were measured by the proposed CL method. Linear relationships were obtained (r>0.977) between the concentrations and CL intensities in all of the tested preparations. The results obtained by the proposed method were compared with those by the titration method in Japanese Pharmacopoeia, and good correlations were obtained between both methods (r>0.919). The CL method is simple and rapid, permitting the completion of single assay within 5 min. The sensitivity and repeatability of the CL method were also superior to those of the titration method.

Keywords : chemiluminescence; lipase activity; pharmaceutical preparations; proenhancer; 2-(4-hydroxyphenyl)-4,5-diphenylimidazole.

Notes

Development of Enzyme Linked Solvent Assay on Open-Well Microchip

Yuki Kudo¹, Jun Tsunokawa¹, Maiko Yagi¹, Hizuru Nakajima¹, Tatsuro Nakagama¹, Kensuke Arai², Yoshihiro Yoshimura² and Katsumi Uchiyama¹

(Received 31 January 2006, Accepted 14 March 2006)

An enzyme-linked immunosorbent assay (ELISA) on the surface of a glass open-well microchip (4 µmφ, 10 µm Depth) was developed. The analytical principle of this method for the determination of immunoglobulin A (IgA) was the same as the conventional sandwich-type ELISA. Firstly, a primary antibody (anti-IgA) was adsorbed on the surface of an open-well microchip, and then an antigen (IgA) and secondary antibody (anti-IgA HRP labeled) were reacted with the adsorbed antibody. The HRP remained on the surface of the open-well microchip, which was determined by using Amplex® Red System with an incident-light fluorescence microscope after the reacyion for 90 seconds. The calibration curve of the IgA standard solution was linear in the range up to 5 ng/ml on 10 µl of the substrate volume. The proposed method with the openwell microchip shortened the reaction time compared to the conventional ELISA with a 96-well plate.

Keywords : surface; droplet; microchannel; ELISA; immunogloblinA.

GC/ECD Peak Pattern Analysis with GPC Pretreatment for Determination of PCBs in Transformer Oil

Naoya Ohmura¹, Thomas R. Glass¹, Kazuhiro Sasaki¹, Takashi Joh² and Yumiko Itoh³

(Received 1 March 2006, Accepted 15 March 2006)

A new peak pattern analysis on GPC/GC/ECD allowing estimation of the total PCB concentration and the Kanechlor composition for transformer oil is described. The oil is treated with a diatomite column containing fuming sulfuric acid, followed by a connected column of silica gel. After elution the sample is further treated by gel permeation chromatography (GPC) and the collected fraction is analyzed by GC/ECD. An algorithm is described to fit the measured GC/ECD peak pattern with a combination of four peak patterns corresponding to the four Kanechlor mixtures, resulting in the total PCB concentration and a predictive proportion of Kanechlors in the sample. Measurements of 19 transformer oil samples using both GPC/GC/ECD and HRGC/HRMS showed a good correlation over the range of 0.2 mg/kg to 2.4 mg/kg total PCBs.

Keywords : PCB; gel permeation chromatography; transformer oil; Electron capture detection; pretreatment.

Analytical Reports

Collaborative Study of Determination of Total Nitrogen in Brown Rice by the Combustion Method According to the Dumas Principle

Hiroshi Horita¹

(Received 24 January 2006, Accepted 28 February 2006)

The total nitrogen contents of brown rice were measured by the combustion method in cooperation with 16 laboratories in Japan. According to the protocol that determined the measuring conditions etc., six samples of brown rice were measured with 3 repetitions and 3 times on different days. The data were removed with Cochran and Grubbs outlier test, and analysis of variance (ANOVA) were carried out for samples No.3~No.6, samples No.1 and No.2 were evaluated as the Youden Pairs. The range of analysis values for six samples calculated from a collaborative trial were as follows: Sr (the standard deviation of laboratory repeatability), 0.003~0.009 g; SR (the standard deviation of laboratory reproducibility), 0.019~0.031 g; RSDR (relative standard deviation of reproducibility), 1.73~2.56%; and HorRat values, 0.44~0.66, respectively. Nested random effects analysis of variance for values of samples No.3~No.6 was conducted and the total variation of ANOVA was divided into three sources of error; 85~93% of the SR contributed to an inter-laboratory error, and contribution of the intra-laboratory error between different days (3~8%) and error with in a sameday (2~7%) were very small. HorRat values of all sample being lower than 1.0 show that the measuring results of this collaborative trial were satisfying. Moreover, RSDR of this trial show that the validity of the measuring method of the total nitrogen content in brown rice by the combustion method was certified.

Keywords : nitrogen content; brown rice; the combustion method; collaborative trial; HorRat.

Preparation and Certification of New Reference Materials, Combustion Dust (JSAC 0511 and JSAC 0512) for Determination of Dioxins

Yoshio Iida¹, Mariko Murayama¹, Takashi Yarita¹, Shozo Asada¹, Yasusuke Matsumoto¹, Yoshinori Takata¹, Yo-ichi Ishibashi¹, Hiroyuki Igaki¹, Tohru Matsumura¹, Tsuneo Hashiba¹, Satoshi Tsuruta¹, Takuzo Takasuga¹, Akihiro Ono¹, Kazutoshi Kakita¹ and Mamoru Sakata¹

(Received 30 January 2006, Accepted 23 March 2006)

The Japan Society for Analytical Chemistry has developed two new certified reference materials (CRMs) for analyses of dioxins (polychlorodibenzo-p-dioxins and polychlorodibenzofurans) and coplanar polychlorobiphenyls. A project team was organized to prepare two kinds of combustion dust and to certify the concentration of dioxins and polychlorobiphenyls. An interlaboratory comparison test was performed by participants from 23 laboratories. In a statistical analysis, z scores in a 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 of dioxins analysis.

Keywords : dioxins; polychlorobiphenyls; combustion dust; interlaboratory comparison test; certified reference material.

Short Communication

Development of Portable Immunoassay Instrument for Screening of PCBs in Transformer Oil

Naoya Ohmura¹, Thomas R. Glass¹, Kazuhiro Sasaki¹, Takashi Joh², Yukihiro Taemi², Naoyuki Yokobori³ and Shingo Terakado⁴

(Received 2 February 2006, Accepted 1 March 2006)

A rapid and simple procedure for the detection of PCBs in transformer oil, using an immunoassay implemented on a handheld battery-powered instrument, is described. Monoclonal anti-PCB antibody is simultaneously mixed with a gold-labeled secondary antibody and oil extract, and then flowed through a disposable cell. The absorbance change in the disposable cell, due to accumulation of the gold-labeled secondary antibody, provides a measure of PCBs present in the oil extract. Measurements of transformer oil using both the immunoassay and HRGC-HRMS showed a good correlation over the range of 0.1 mg/kg to 8.4 mg/kg total PCBs. Eighty six transformer oil samples were screened using the immunoassay at a cutoff concentration of 0.4 mg/kg total PCBs with no false positives and no false negatives observed. The same result was obtained when the cut off concentration was raised to 5.0 mg/kg. The results suggest that the described immunoassay can provide a fast and effective alternative to other procedures, such as GC-ECD for screening transformer oil for PCBs.

Keywords : PCB; immunoassay; transformer oil; rapid detection; portable instrument.

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