The author has studied capillary electrophoresis-chemiluminescence detection system. Various types of the chemiluminescence detection cells for capillary electrophoresis were developed, including flow- and batch-type cells. The author took advantage of several chemiluminescence reagents such as luminol, peroxyoxalate, ruthenium(II) complex, and 1,10-phenanthroline in the system, and also introduced several separation modes such as micellar electrokinetic chromatography, capillary isoelectric focusing, and capillary gel electrophoresis to the system. Consequently, a variety of analytes including amino acids, peptides, proteins, saccharides, nucleic acids, nucleosides, metal ions, metal complexes, alkaloides, fluorescence compounds, fluorescence compound-including liposomes, and phenolic compounds were analyzed by means of capillary electrophoresis-chemiluminescence detection system. The system provided excellent selectivity and sensitivity. The sensitivity of the system was better than those of absorption and fluorescence detection systems; for example, the detection limit for luminol was 1.5×10⁻¹¹ M (S/N=3), representing the highest sensitivity of luminol yet reported. The system was applied to microchip capillary electrophoresis and immunoassay. The author also considered on peak shape in batch-type chemiluminescence detection cell for capillary electrophoresis.

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A analytical method was developed for the determination of phthalate ester plasticizers {diisononylphthalate (DINP), diisodecylphthalate (DIDP) and diisotridecylphthalate (DITP)} in the atmosphere by liquid-chromatography/tandem mass spectrometry(LC/MS/MS). The ionization mode was positive-APCI (atmospheric pressure chemical ionization) and [M+H]⁺ ions were formed, which then fragmented by collosion with nitrogen. Sample air was drawn for 24 h at a constant flow rate (12∼14 l/min) through a quartz fiber filter. After the collected substances were extracted into acetonitrile, di-(2-ethylhexyl)phthalate-d₄ (DEHP-d₄) was added as an internal standard. The recoveries, relative standard deviation (RSD) and limit of detection (LOD) were 94∼102%, 4.3∼8.7% and 0.05∼0.8 ng/m³, respectively. DINP and DIDP were detected in outdoor and indoor air samples, including clearn room air; concentrations were 1.2∼9.6 and 0.1∼1.4 ng/m³, respectively. Because these phthalate esters are semi-volatile and include a mixture of many isomers, it is hard to obtain high analytical accuracy and precision by gaschromatograhy. The present method could be used to determine DINP and DIDP in air with high sensitivity.

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A diprotic acid dye eosin and a tertiary amine quinine form a red 1:2 associate in neutral media. When trace amounts of cetylpyridinium salt are added to the media, in which the red 1:2 associate co-exists, one quinine is substituted for cetylpyridinium salt and a eosin-quinine-cetylpyridinium associate(1:1:1) is newly formed. Therefore, the extractability of cetylpyridinium ion is enhanced. As a result, a highly sensitive spectrophotometry can be developed for the determination of trace amounts of cetylpyridinium salt. The linearity of the calibration graph is good over the range of 2.5×10⁻⁷∼1.5×10⁻⁶ mol dm⁻³ (=M) with an RSD of 0.37%. The proposed method can be applied to the trace analysis of cetylpyridinium salt and quaternary ammonium salts.

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When trace oxygen is analyzed by the method of inert gas fusion-infrared absorption, it is important to make a measurement immediately after the oxide on the surface of a sample has been removed. In general, file grinding, chemical polishing, and electrolytic polishing, etc. were done as a method for removing the surface oxide. However, oxide cannot be completely removed, because oxidation occurs immediately again after these procedures. The surface oxide begins reduction from 750°C by carbon in the graphite crucible of the inert gas fusion. The surface oxide was removed in the temperature range of 900°C∼1050°C. At 1050°C or more, the sample had melted. Therefore, the sample was preheated for 60 seconds at 1000°C in an inert gas atmosphere in a graphite crucible. Afterwards, purified Sn was added using dual sample/flux introduction system. It was melted at 2300°C together with the sample, and the oxygen in the sample was measured. The interference of Mn as a getter of carbon monoxide in an oxygen analysis was eliminated by the addition of Sn, and an analysis of oxygen became possible after three minutes. An IR detector was installed in the absorption cell, whose length was five-times as long as that in the conventional model. The S/N was improved by five times. A sample of 2 g was analyzed using a large-volume graphite crucible. The analytical result of oxygen in a steel sample JSS GS-6b (oxygen concentration 3.4 μg g⁻¹) became 2.9 μg g⁻¹, except for the surface oxygen. JSS GS-2c (oxygen concentration 17.5 μg g⁻¹) became 16.8 μg g⁻¹, and both standard deviations was 0.2 μg g⁻¹.

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An extraction method for amino acids in soil samples to determine their concentrations and D/L ratios was developed. The amounts of amino acids extracted with a mixture of HF and HCl were much more than those extracted with hot water. Digestion of soil matrix with HF is necessary for extracting amino acids in soils. Since racemization of chiral amino acids occurred during extraction, different periods of HF extraction were employed to determine the initial D/L ratio. The extract was subjected to acid hydrolysis with 6 M HCl for 2 h to obtain free amino acids. The present procedure is promising to study amino acids in geological samples.

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A spectrophotometric FIA method for the determination of the total base number (TBN) and the total acid number (TAN) in a lubricant, where a nonaqueous solvent (toluene 52%/H₂O 1%/2-propanol 47%v/v) is used as an acid-base buffer solution, is proposed. The method is based on measurements of the absorbance change of an indicator contained in the acid-base buffer solution, which is generated due to a neutralization reaction of an acid or base in the lubricant with the acid-base buffer solution. For determining of TBN, a lubricant sample was injected into the carrier of the nonaqueous solvent and merged with a stream of perchloric acid (HClO₄) solution prepared with the nonaqueous solvent. The base compound in the sample solution was neutralized with HClO₄. An excess of HClO₄ after the neutralization reaction was subsequently merged with a stream of tetrabutylammonium salt of trifluoroacetic acid (TFA•TBA) solution containing an indicator (m-cresol purple); the mixed stream was led to a spectrophotometric detector. As a result of mixing three streams, the composition of the TFA/TFA•TBA buffer changed. This change gave rise to an absorbance change of the acidic form of m-cresol purple at 536 nm. The absorbance change was monitored with a spectrophotometric detector, and a peak-shape signal was obtained for the base sample. An identical linear relationship between the peak height and the concentration of the base sample was obtained for several base additives of a lubricant, such as calcium sulfonate and calcium phenate etc, irrespective of their basicity. The TBN of a lubricant sample, which contained both base and acid additives, could be determined by the proposed method without interference from the coexistence of acid additives. A good linear correlation was found between the TBN obtained by our FIA method and that obtained by a conventional neutralization titration method. For the determination of that, a similar flow system to that for the determination of TBN was constructed from the streams of a carrier, a tetrabutylammonium hydroxide solution and tetrametylguanidine of hydrochloric acid solution containing α-naphtholbenzein. A single linear calibration line was obtained for several acid additives of a lubricant, such as zinc dialkyldithiophosphate and oleic acid. A good correlation for the analytical results of TAN was also obtained between the two methods. The proposed method was successfully applied to the determination of TBN and TAN of real lubricants with a sampling rate of 20 h⁻¹, and solvent consumption was as low as 4.5 ml/sample.

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Solutions of cyanide ions of approximately 1000 mg kg⁻¹ were prepared with 0.2∼1.5 mol dm⁻³ KOH solutions and stored in high-density polyethylene and PFA bottles at 8°C and 25°C. The concentrations of the solutions were determined by a complexometric titration using a nickel titrant as a reliable reference and murexide as an indicator. The decreases in the concentrations were −1.7∼−2.8%/year at 8°C and −19∼−26%/year at 25°C. The higher was the KOH concentration, the smaller was the decrease in the cyanide concentration. The material of the bottle had no influence on the storage stability of the solution. The storage stability of potassium cyanide was similarly studied. The purity of potassium cyanide might decrease by more than 0.10%/year at 25°C, even if it is stored in an sealed bottle.

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The flow injection fluorometry of an ultra-trace amount of magnesium ion was investigated by an on-line concentration method using a PTFE tube. In a weak alkaline solution, magnesium ions were adsorbed and concentrated on the inner surface of a PTFE tube which had been treated with a 2 M NaOH solution for 3 hours at 70°C. Then, magnesium adsorbed on PTFE was eluted with 0.1 M HCl quantitatively, and then mixed with a N,N'-bis-salicylidene-2,3-diaminobenzofuran(SABF) dioxane solution and dimethylamine buffer. Magnesium ions reacted with SABF and formed a Mg-SABF complex in the flow tube, and was determined by on-line fluorometry. Although the presence of calcium ions interfered with the concentration of magnesium, it was removed by the addition of o,o'-bis(2-aminoethyl)ethyleneglycol-N,N,N',N'-tetraacetic acid(GEDTA) as a masking agent. The optimum conditions were as follows: inner diameter of PTFE tube, 0.5 mm; length of PTFE tube, 3 m; concentration pH, 10.3; sample flow rate, 2 ml/min; complexing pH, 10.4; concentration time, 3 min; carrier, 50% dioxane; measurement wavelength: E_x=475 nm, E_m=545 nm. The detection limit was 82 ppt. The result for the determination of magnesium was 3.1 ppb in distilled water, which shows good agreement with the value obtained by ICP-AES.

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There is an important discussion on the condition of alkaline treatment in case of determination of PCBs in soil/sediment; that is, the official method at present which consists of alkaline treatment of sample over 80°C as pretreatment process will cause dechlorination of PCBs. A study group of the Japan Society for Analytical Chemistry has been organized to improve it. The proposed conditions against the official method (method A) were; extraction using acetone (method B) or toluene (method C) is followed by alkaline treatment of the extract at room temperature instead of at 80°C. Hexane extraction and chromatographic clean-up procedure after alkaline treatment in method B and method C are same as method A. An interlaboratory comparison test was performed by participation of 7 laboratories. As the result, there are no significant difference in quantitative data obtained from 3 methods except high values in 1∼3 Cl-substituted homologues from method C. Study on rate of dechlorination of PCB homologues has not programmed in this experiment.

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A simple and low cost mesurement method for determination of bisphenol A (BPA) in drinking water and river water by high-performance liquid chromatography (HPLC) with an ultraviolet detecter (UV) has been studied. As a result, good linearity of the calibration curve was obtained in the concentration range from 0.01 mg/l to 1 mg/l. The detection limit, based on S/N=3, was 0.0065 μg/ml for BPA. Acetone was recommended for the elution of BPA from the solid phases. The recoveries for BPA from river water spiked at a mesurement concentration of 0.1 mg/l was 55.3∼78.7%, and the relative standard deviations was 5.2∼7.1% by an activated carbon column method. This measurement method could be successfully applied to the determination of BPA in drinking water and river water.

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[in Japanese]

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