BUNSEKI KAGAKU Abstracts

Vol. 53 No. 1

January, 2004

Research Papers

Development of a micro-flow titration method and application to acid-base titration

Hironobu Konishi¹, Toshio Takayanagi¹, Mitsuko Oshima¹ and Shoji Motomizu¹

(Received 9 May 2003, Accepted 29 September 2003)

A flow titration analysis method based on flow ratiometry was developed in this study from the viewpoint of simplicity, rapidity, automation, and cost efficiency. Sample and titrant solutions react while the solutions are continuously propelled by individual pumps at different flow rates. The flow rates are accurately controlled and changed independently, and the color change of an indicator gives an equivalent point. The concentration of analyte was determined by using the ratio of the flow rate and the equivalent point. The fundamental properties of the flow titration method were evaluated through acid-base titration, and compared with the conventional manual titration. When Phenolphthalein or Cresol Red was used as an indicator added in either the sample solution or the titrant solution, linear calibration graphs were obtained for all titrations examined, including strong and weak acids. The proposed method was applied to the titration of carbonate salt using Bromocresol Green and Phenolphthalein. Two isolated end-points were obtained in one sequential measurement corresponding to carbonate and bicarbonate ions. The proposed titration method was applied to the analysis of commercial vinegar samples. The results agreed well with the ones obtained by the conventional titration method; the relative standard deviations for the end point were within 0.3%. The volume of wastewater per one measurement can be reduced down to about 100 µl by the proposed method, while a practical method requires about 50 ml.

Keywords : flow titration analysis; flow ratiometry; acid-base titration.

Identification of composite particles of diesel exhaust particles and

Kenichiro Suzuki¹, Bunbunoshin Tomiyasu² and Yoshimasa Nihei¹

(Received 20 May 2003, Accepted 16 October 2003)

We made a close analysis of individual atmospheric particles sampled near to road traffic and a railroad with a personal air sampler using a field emission type scanning electron microscope. From the results of an electron microprobe analysis, the particles were classified into five types. Some particles had minute attachments on them. From comparisons of the X-ray spectra of the carrier particles and their attachments, we concluded that they were composite particles of a Fe carrier particle of railroad origin and the attached diesel exhaust particles.

Keywords : complex particle; diesel exhaust particle; Fe particle; electron probe micro analyzer; individual particle analysis.

Technical Papers

Rapid determination of lead in thermally cracked gasoline by graphite furnace AAS

Yoshikazu Nakamoto¹

(Received 20 May 2003, Accepted 21 September 2003)

A simple and rapid method was established for the direct determination of lead in thermally cracked gasoline using graphite-furnace AAS. Lead compounds in thermally cracked gasoline are known to be catalyst poisons in the aromatization process. Therefore, it is important to determine trace lead in thermally cracked gasoline. The volatilization of organic lead from the furnace was suppressed by the addition of iodine and the atomic absorption sensitivities of inorganic and organic lead compound became identical. Therefore, it was possible to use inorganic lead as a standard compound for the calibration curve. The detection limit and relative standard deviation were estimated to be 5 ng g^-1 and 3.8% for lead determination (20 ng ml^-1), respectively. The interference of thermally cracked gasolines and other metals were not observed. Analytical time of the proposed method was 20 min per one sample.

Keywords : lead; matrix modifier; iodine; graphite furnace AAS; thermally cracked gasoline.

Sensitive determination of aluminum in parenteral solutions and injections by HPLC with fluorescence detection using lumogallion

Naoki Fujita¹, Hideki Kobayashi¹, Toshiyuki Enami¹, Norikazu Nagae¹ and Noah Charleston¹

(Received 25 August 2003, Accepted 9 October 2003)

A sensitive fluorometric method for the determination of aluminum has been developed using lumogallion [5-Chloro-2-hydroxy-3-(2,4-dihydroxy-phenylazo) benzenesulfonic acid]. Aluminum is known to form a fluorescent chelate with lumogallion. The aluminum-lumogallion complex was separated on a reversed-phase column within 6 minutes and detected by a fluorescence detector at 505 nm (excitation wavelength) and 574 nm (emission wavelength). The present method enabled detection down to 0.1 µg/l in an aqueous solution, and the relative standard deviation (RSD) at 50 µg/l of aluminum was less than 1%. We applied it to the determination of aluminum in not only parenteral solutions and injections including a matrix, such as vitamins, glucose and lipid, but also to amino acids as their ingredients. The recovery of this method was generally over 90%.

Keywords : aluminum; lumogallion; HPLC; TPN; QC.

Ion chromatography of selenite and selenate using column packing with poly(vinyl alcohol) gel

Akinori Isozaki¹, Kenji Yoshikawa¹ and Hisomu Nagashima²

(Received 26 August 2003, Accepted 4 November 2003)

A method for the determination of 9 inorganic anions was investigated by ion chromatography using a poly(vinyl alcohol) column (Shodex IC SI-90 4E) with suppressed conductivity detection. The optimal mobile phase was 6.0 mM sodium tetraborate and 20.0 mM boric acid for the simultaneous determination a mixture of anions (F^-, Cl^-, NO₂^-, Br^-, NO₃^-, SeO₃^2-, HPO₄^2-, SO₄^2-, SeO₄^2-) under the following conditions: flow rate, 0.8 ml/min; scavenger, 12.5 mM sulfuric acid; column temperature, 40°C. The 9 anions were efficiently separated in about 20 minutes. Calibration curves from the peak areas of 9 anions were linear with high correlation coefficients of more than 0.999, and the relative standard deviations (RSD) of the peak areas were about 1% from 10 repeated measurements. The limit of detection was from 1~30 ng/ml for 7 anions, 28 ng/ml for SeO₃^2- ion, and 17 ng/ml for SeO₄^2- ion. This method was applied to the determination of selenium in organic selenium compounds. The content of selenium by this method was in good agreement with that calculated from the molecular formula. It was found that selenium in an absorbent from the combustion of a sample exists only in the selenite form.

Keywords : ion chromatography; poly(vinyl alcohol) column; sodium tetraborate-boric acid eluent; selenite and selenate; oxygen flask-combustion method.

Notes

Determination of the content of bisphenol-A and its uncertainties by HPLC

Shigetomo Matsuyama¹, Jyunichi Kumon², Hisashi Takahagi³, Takeshi Saito¹, Kayori Shimada¹, Masanao Itakura¹ and Shinichi Kinugasa¹

(Received 7 August 2003, Accepted 20 October 2003)

An accurate analysis of the amount of Bisphenol-A (BPA) in Polycarbonate (PC) was examined. BPA was extracted from PC under the Japanese food sanitation law (FSL). A new method was developed to determine the recovery under FSL by modifying the standard addition method. The recovery was determined to be 0.96 from this experiment. A comprehensive list of relevant sources of uncertainty under FSL operation was assembled. The uncertainty of the amount of BPA in PC was evaluated under the “guide to the expression of uncertainty in measurement (GUM)”. The amount of BPA in PC was evaluated: (38.89±1.59) µg/g (k=2); here, k represents the coverage factor.

Keywords : bisphenol-A; recovery; standard addition method; uncertainty; Japanese food sanitation law.

Precise determination of minor alloyed elements in steel by glow discharge optical emission spectrometry with pulsed-voltage modulation technique

Kazuaki Wagatsuma¹

(Received 15 July 2003, Accepted 6 November 2003)

A pulsed-voltage was applied to a glow discharge lamp for a modulation detection technique in d.c. glow discharge optical emission spectrometry. Emission signals from the glow discharge plasma were modulated by a cyclic variation in the discharge voltage so that only the desired signals would be detected without any noise with a lock-in amplifier. Molybdenum and vanadium determinations in a steel sample having contents of several 0.001 mass% was performed to estimate the analytical precision. The relative standard deviations of the intensities of the Mo I 379.65 nm and the V II 310.10 nm were 0.2~0.6% in the modulation method, whereas they were 2.6~3.6% in a conventional detection method. Compared with the result by the conventional detection method, the modulation method yielded a better precision in the analytical values. This technique contributes to the precise determination of minor elements alloyed in steels.

Keywords : glow discharge optical emission spectrometry; voltage modulation; precision; minor alloyed element; molybdenum; vanadium; steel.

Technical Letters

Determination of lithium in food by flame photometry

Yuzo Tamari¹ and Kazuyuki Tsuchiya¹

(Received 2 July 2003, Accepted 1 October 2003)

Lithium has been used as a medicine for the remedy and prevention of manic-depressive psychosis. It is, however, essential to monitor the blood lithium concentration of patients during their hospital-treatments, because the intake amount of lithium as a remedy is reflected in the blood lithium concentration, which is significantly close to a toxic level. Since continual lithium intake with daily meals is expected to prevent manic-depressive psychosis at an early stage, it is important to know the food lithium content. In this work, the effects of matrix constituents (Na⁺, K⁺, Ca²⁺, Mg²⁺ and PO₄^3-) of food on the determination of lithium by flame photometry were studied. Since there was no interference of the matrix ions, the method was applied to food samples: fresh fish (30~84 ng/g), dry-processed fish (731 and 1790 ng/g), table-salts (667~2340 ng/g), infant formulas (120~160 ng/g) and eastern medicines, such as mammalian bone and oyster-shell (18700 and 20200 ng/g).

Keywords : lithium; flame photometry; matrix ions; food samples.

Characterization of individual particles in a PM_2.5 fraction of an urban air sample

Satoshi Nakano¹, Masako Hirano¹, Bunbunoshin Tomiyasu² and Yoshimasa Nihei¹

(Received 19 May 2003, Accepted 7 October 2003)

The analysis of individual particles in a PM_2.5 fraction of an urban air sample was carried out using scanning electron and electron microprobe analysis. Sampling was done using a portable cascade impactor with a silver substrate to obtain information about some lighter elements(C, N and O). It was found that particles in PM_2.5 could be classified into 6 groups based on their shape and composition. Some of the groups could be attributed to specific anthropogenic origins. We observed a difference in the deformation of particles during the microprobe analysis, which might provide unique additional information concerning the classification protocols in the future.

Keywords : PM_2.5; DEP; light elements; shape; EPMA.

Dissolution procedure for the determination of major and minor elements in La-Sr-Ga-Nb oxide by inductively coupled plasma-optical emission spectrometry

Kan-ichi Makabe¹, Kunio Takada¹ and Kazuaki Wagatsuma¹

(Received 3 September 2003, Accepted 8 October 2003)

This paper describes a dissolution method for La-Sr-Ga-Nb (LSGN) oxide samples, which are hardly decomposed by conventional acid treatments. The LSGN oxides are not dissolved in any acid solution and do not undergo fusion with alkaline reagents, such as Na₂CO₃. However, the sample can undergo fusion with Na₂B₄O₇ powder. A sample (50 mg) was fused with 1 g of Na₂B₄O₇ in a Pt crucible, whose inside wall was covered with pre-melted Na₂B₄O₇ (1 g). The melted product was cooled and then dissolved with a mixture of 30 ml HNO₃ (1:1), 2.5 ml H₂O₂, and 1 g tartaric acid. After the addition of 1.5 ml of H₂O₂ and 5 ml of an Y solution (5 mg/ml) as an internal standard, the solution was diluted to 100 ml and measured by inductively coupled plasma-optical emission spectrometry. Two samples having different chemical compositions were analyzed to yield each in good agreement with the analytical values between two individual measurements.

Keywords : La-Sr-Ga-Nb oxid; fusion with Na₂B₄O₇; ICP-OES.

Determination of Ni-Pd-P alloys by inductively coupled plasma-optical emission spectrometry

Yûetsu Danzaki¹ and Kazuaki Wagatsuma¹

(Received 2 June 2003, Accepted 9 October 2003)

For the precise quantification of Ni-Pd-P alloys by inductively coupled plasma-optical emission spectrometry, non-spectral interferences of K should be corrected because the standard solution for P is usually prepared by using KH₂PO₄. An analytical method is suggested to correct the influence of K; after dissolution of the sample in HNO₃-HCl, a standard solution of K is added to the sample solution so that the amount of K can be controlled to be the same as in the P standard solution with an error of ±1 mg.

Keywords : Ni-Pd-P alloys; HNO₃-HCl dissolution; influence of K; ICP-OES.

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