Kunio Nagashima

Spectrophotometric method for the determination of an anionic surfactant without liquid-liquid extraction

Abstract A simple method for spectrophotometric determination of an anionic surfactant (0–15xa0μg) was studied. The ion associate formed between sodium dodecyl sulfate (SDS) and Rhodamine 6G was adsorbed onto the wall of a PTFE vessel by vigorous shaking. After the resultant solution was discarded, the ion associate was dissolved in methyl cellosolve and its absorbance measured at 534xa0nm. The apparent molar absorptivity for SDS was 8.5×104xa0lxa0mol−1xa0cm−1. The coefficient of variation for the determination of 7.2xa0μg of SDS in 10xa0ml of sample was 4.5% (n=6). Greater sensitivity could be achieved by using a 50xa0ml sample.

Simple method for spectrophotometric determination of cationic surfactants without liquid–liquid extraction

Abstract A simple method for the spectrophotometric determination of cationic surfactants was studied. The ion associate of tetradecyl-dimethylbenzylammonium chloride (Zephiramine) and tetrabromophenolphthalein ethyl ester (TBPE) were adsorbed onto the walls of a PTFE vessel by vigorous shaking. After discarding the resulting solution, the ion associate was dissolved in methyl cellosolve and its absorbance was measured at 605xa0nm. The molar absorptivity for Zephiramine was 7.88×10 4 xa0lxa0mol −1 xa0cm −1 .

Development of a monitoring tape for phosgene in air.

A porous cellulose tape impregnated with a processing solution that includes 4-p-nitroben-zylpyridine, N-benzylaniline and methanol is a highly sensitive means of detecting phosgene and maintains stable sensitivity for at least three months in air in a desiccator. When the sample including phosgene was passed through the tape, the color of tape changed to red. The degree of color change was proportional to the concentration of phosgene at a constant sampling time and flow rate. The degree of color change could be recorded by measuring the intensity of reflecting light (555 nm). The detection limit was 6 ppb for phosgene with a sampling time of 60 sec and a flow rate of 400 ml/min. Reproducibility tests showed that the relative standard deviation of response (n = 10) was 2.6% for 0.2 ppm phosgene. No interference was observed from ethanol (1 vol.%), trichloroethylene (1 vol.%), acetone (1 vol.%), carbon dioxide (4.9 vol.%), carbon monoxide (100 ppm), nitrogen dioxide (100 ppm), sulfur dioxide (50 ppm), hydrogen chloride gas (5 ppm), chlorine (3 ppm), acetic acid gas (24 ppm), ammonia (40 ppm), or benzyl chloride (20 ppm).

Determination of sulphate and phosphate by flow-injection analysis using a barium chloranilate packed column

SummaryA flow-injection analysis of sulphate using a reaction column packed with barium chloranilate (BaCh) is described. The chloranilate ion released by the reaction is monitored at the isosbestic point (310 nm) of chloranilate. An aqueous solution of 2-propanol (60%) is used as the carrier solution at a flow-rate of 1 ml . min−1. The linear dynamic range of the detection system is approximately 2.5×10−6∼1.0×10−3 mol/l per 10 μl sample injection. The time required for a determination is only 20 s per sample injection. The method has also been applied to the amplified determination of phosphate by reaction with molybdate resulting from the decomposition of molybdophosphate (H3PO4.MoO3) extracted.

An automatic measurement of hydrogen cyanide in air by a monitoring tape method

Abstract An automatic monitor has been developed for hydrogen cyanide gas in air using a sensitive tape for hydrogen cyanide. It is based on color change of the tape by reaction with hydrogen cyanide. The tape containing silica gel as an absorbent and impregnated with a processing solution that includes 4,4′-bis(dimethylamino)diphenylmethane(tetrabase), copper(II) acetate, butylhydroxytoluene, glycerin and methanol was found to be a highly sensitive means of detecting hydrogen cyanide gas and it maintained stable sensitivity for at least a month in the air of a desiccator. When an air sample including hydrogen cyanide gas was passed through the tape, hydrogen cyanide was absorbed on the surface of the tape, and it reacted with copper(I) ion producing CuCN; then the tetrabase was oxidized by Cu(II) ion to form a stain. The intensity of the stain was proportional to the concentration of hydrogen cyanide at a constant sampling time and flow rate, and it could be recorded by measuring the intensity of reflecting light (555xa0nm). The detection limit ( S / N xa0=xa03) was 0.2xa0ppm for hydrogen cyanide gas with a sampling time of 60xa0s and a flow rate of 400xa0ml/min. Reproducibility tests showed that the relative standard deviation of response ( n xa0=xa06) was 2.2% for 5xa0ppm hydrogen cyanide. No response was observed from methanol (1xa0vol.%), acetone (1xa0vol.%), carbon dioxide (4.9xa0vol.%), carbon monoxide (100xa0ppm), sulfur dioxide (50xa0ppm), hydrogen chloride gas (8xa0ppm), nitrogen monoxide (50xa0ppm), nitrogen dioxide (4xa0ppm), or ammonia (40xa0ppm).

Development of a monitoring tape for ammonia gas in air by fluorescence detection

A porous cellulose tape impregnated with a processing solution that includes Eosine Bluish, p-toluenesulfonic acid, glycerin and methanol is a highly sensitive means of detecting ammonia gas in air. The monitoring tape for ammonia gas is based on the change in fluorescence intensity of a pH indicator (Eosine Bluish) put on the tape. Exposure to the sample including ammonia increased the pH of a solution existing in the tape. The compound produced with ammonia gas shows an excitation maximum at 460 nm and a fluorescence maximum at 550 nm. The degree of the change in fluorescence intensity was proportional to the concentration of ammonia gas at a constant sampling time and flow-rate. The tape could detect 0.1 ppm of ammonia gas at a sampling time of 40 s and a flow rate of 400 ml/min. No interference was observed from carbon monoxide (100 ppm), carbon dioxide (4.9%, v/v), nitrogen dioxide (100 ppm), sulfur dioxide (50 ppm), acetone (1%, v/v), ethanol (1%, v/v), trichloroethylene (1%, v/v), chlorine (3 ppm), or hydrogen chloride gas (5 ppm).

Complexation behavior of mono- and disaccharides by the vinylbenzeneboronic acid-divinylbenzene copolymer resins packed in a high-performance liquid chromatographic column.

Using an HPLC column packed with monodispersed vinylbenzeneboronic acid-divinylbenzene (V-D) copolymer resins, the elution behaviors of the mono- and disaccharides were studied under different pH mobile phases. The monodispersed V-D copolymer resins were prepared by the copolymerization of 4-vinylbenzeneboronic acid and divinylbenzene in the presence of template silica gel particles (particle size: 5 microm; pore size: 10 nm), followed by dissolution of the template silica gel using a NaOH solution. Similarly, styrene-divinylbenzene (S-D) copolymer resins as the control resins were also synthesized. The transmission electron micrographs of these polymer resins revealed a good monodispersity. The complexation behavior of the saccharides was evaluated by comparison of the peak area eluted through the V-D column for that through the S-D column. Four aldopentoses (D-ribose, D-arabinose, D-xylose, and D-lyxose) and four aldohexoses (D-glucose, D-mannose, D-galactose, and D-talose) were retained completely at pH 11.9. Especially, ribose and talose were totally retained even under acidic and neutral conditions. For the disaccharides, unlike sucrose and maltose, palatinose was completely retained in basic mobile phases.

Improvement of a monitoring tape for nitrogen dioxide in air

A porous cellulose tape containing a silica gel that was previously impregnated with a processing solution containing p-toluenesulfonic acid, sulfanilic acid, N-1-naphthyl ethylene diamine dihydrochloride, ethylene glycol and methanol has been developed to provide a highly sensitive detection of nitrogen dioxide in air. When the sample including nitrogen dioxide was passed through the tape, the color of tape changed to red, and the degree of color change could be recorded by measuring the intensity of reflecting light (555 nm). The calibration graph was linear up to approximately 0.10 ppm. The detection limit was 0.5 ppb for nitrogen dioxide with a sampling time of 8 min and a flow rate of 60 ml min(-1). No interferences were observed from ammonia (40 ppm), sulfur dioxide (51 ppm), carbon dioxide (21%), ozone (0.75 ppm), hydrogen sulfide (27 ppm) or nitrogen monoxide (99 ppm).

Determination of trace amounts of sulfide in human serum by high-performance liquid chromatography with fluorometric detection after derivatization with 2-amino-5-N,N-diethylaminotoluene and iron(III)

Abstract A fluorometric high-performance liquid-chromatographic method is described for the determination of sulfide in human serum. The sulfide ion had been derived into a fluorescent compound with 2-amino-5-N, N-diethylaminotoluene and Fe (III) under an acidic condition. The compound was extracted into 2-octanol as an ion-pair with sodium 1-octane sulfonate. The extract was separated by a reversed phase method (column, Inertsil ODS-2, 250mm × 4.6mm i.d.; mobile phase, 90% (V/V) acetonitrile aqueous solution containing sodium 1-octanesulfonate as a counter ion reagent; flow rate 0.5cm3· min−1 and detected fluorometrically (Ex. 640nm; Em. 675nm). The sulfide ion could be determined over the range from 4.4 × 10−10M to 4.4 × 10−7M. The coefficient of variation at 4.4 × 10−8M of sulfide was 3.2% (n=7). The range of concentration of sulfide ion in human serum were from 3.04 × 10−8M to 2.24 × 10−8M by this method.

Preparation of monodispersed vinylpyridine–divinylbenzene porous copolymer resins and their application to high-performance liquid chromatographic separation of aromatic amines

For the separation of aromatic amines, two types of monodispersed porous polymer resins were prepared by the copolymerization of 2-vinylpyridine and 4-vinylpyridine with divinylbenzene in the presence of template silica gel particles (particle size 5 microm), followed by dissolution of the template silica gel in an alkaline solution. The transmission electron micrographs and the scanning electron micrograph revealed that these templated polymer resins have a spherical morphology with a good monodispersity and porous structure. Using these monodispersed polymer resins, the high-performance liquid chromatographic separation of aromatic amines in the mobile phases of pHs 2.0, 2.9, 4.1, 7.2 and 11.7 were carried out. The 2-vinylpyridine-divinylbenzene copolymer resins showed slightly stronger retentions for aromatic amines than the 4-vinylpyridine-divinylbenzene copolymer resins. Under acidic conditions (around pH 2.0), aniline and the toluidines showed no retention on these copolymer resins due to the repulsion between the cationic forms of these amines and pyridinium cations in the stationary phase, whereas less basic aromatic amines or non-basic acetanilide showed slight retentions. Above pH 4.1, the separation of aromatic amines with these polymer resins showed a typical reversed-phase mode separation. Therefore, the separation patterns of aromatic amines are effectively tunable by changing the pH value of the mobile phases. A good separation of eight aromatic amines was achieved at pH 2.9 using the 2-vinylpyridine-divinylbenzene copolymer resins.