The separation of each aliphatic amines was investigated by high performance liguid chromatography as their 2, 4-DNP derivatives. The derivatization was carried out as follows. A slightly excess of 2, 4-dinitrofluorobenzene and fine powder of sodium bicarbonate were added to an ethanol solution of amine in a flask equipped with a magnetic stirrer and a refluxcondenser and heated at 60°C for 1 h. After cooling, the mixture was diluted to the mark with ethanol. An aliquot of the solution (1 μl) was injected with a micro-syringe into the top of the column. A Yanagimoto LC-1100 HPLC equipped with a 254-nm UV detector was used and the separation was carried out on a silica column (LiChrospher SI-100, Merck), a gel column (Porous polymer-3011, Hitachi and Yanako-gel 5510-C) and a reversed phase column (RP-18, 5 μm, Merck), respectively. The mobile phases used were 2, 2, 4-trimethylpentane/1-butanol for the silica-column and methanol/water for both gel- and reversed column, respectively. The low aliphatic amines (C₁C₄) were completely separated by use of the silica column and the higher aliphatic amines were separated by use of the gel column with methanol/2, 2, 4-trimethylpentane as an eluent, and reversed phase column was used to all range of aliphatic amines with high efficiency.

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Simultaneous determination of binary mixture of nitrate and nitrite by means of ion selective electrodes has been investigated. Coated-wire electrodes based on octadecanol were used. The selectivity coefficient of nitrate ion electrode to nitrite was 0.30.4, while that of nitrite ion electrode to nitrate became 0.81.0 by the addition of p-t-octylphenol into the membrane. Simultaneous determination of nitrate and nitrite with these electrodes was found to be possible in the concentration range between 10^-2 M and 10^-4 M and in the concentration ratio between 1:1 and 1:5 with the relative standard deviation less than 15%. The principle of this method is as follows; in the modified Nernst equations for nitrate (3) and nitrite (2) electrodes,
E3=E0₃-S3 log {a (NO₃)+K_3-2a(NO₂)+F3}
……(1)
E2=E0₂-S2 log {a(NO₂)+K_2-3a(NO₃)+F2}……(2)
slope S, intercept E0 and correction term F for the curvature of calibration curve at low concentrations can be calculated from the potentiometric response curve for main anion. After the determination of the selectivity coefficients K with the known sample, the right hand side of Eq. 1 or 2 gives a calculated potential E_calc with one set of activity values a (NO₃) and a(NO₂). Simultaneous determination can be made by estimating a(NO₃) and a(NO₂) so as to minimize the following H value,
H=√(E3_calc-E3_obs)²+(E2_calc-E2_obs)²(3)
where E_obs is the observed potential.

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When a carbon tube soaked in tantalum solution is heated over 2000°C, tantalum carbide (TaC) is formed on the surface of the tube. The characteristics of such a tube in atomic absorption spectrometry has been investigated. A commercial standard carbon tube was soaked in a 5 % tantalum fluoride solution under reduced pressure for 90 min and was baked at 2400°C by the power supply of a flameless atomizer. This treatment was repeated twice. Tantalum carbide formed on the surface of the treated tube was identified by X-ray diffraction method. This method enabled a simultaneous treatment of many tubes. The relative standard deviation of tin atomic absorption was 8.1 % among 9 simultaneously treated tubes. The temperature-time characteristics of the treated tubes were almost same as those of untreated tubes. Although the peak enhancement was observed among several elements, signals of elements forming refractory oxide like as titanium were depressed because of the decrease in the reducing power of the tube. The tantalum carbide treatment prolonged the life of the tube; when 1.0ng of nickel in 0.1 N nitric acid was used as the sample, the treated tube was broken only after 280 times of firing, whereas an untreated tube was broken after 186 times of firing The weight loss of the treated tube by firing was almost same as that of an untreated tube, but the formation of fine carbon powder was not observed on the surface. Therefore, the apparent absorption due to scattering of fine carbon powder did not appear, and the signals obtained by the treated tube were constant regardless of the age of the tube. The results of surface analysis by EPMA and electron microscope indicated that the treated tube was not coated with tantalum carbide but minute holes of the surface of a carbon tube was filled by tantalum cabide. A prolongation of soaking time and/or the further repetition of the treatment enabled formation of tantalum carbide layer, but caused a decrease of the reducing power of the tube.

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A pyroxyline membrane entrapping β-D-glucose oxidase (GOD) was installed on an oxygen electrode, and used for the inhibitor screening in vitro. The sensor showed good linear response to the glucose concentration from 0.1 mM up to 6 mM. The apparent Michaelis constant of the immobilized GOD was (1735) mM depending upon the entrapping condition. Sodium nitrate and semicarbazide showed competitive inhibition with inhibitor constant of 13 mM and 43 mM, respectively. Cupric sulfate and mercuric chloride showed more involved mode of inhibition closely related to non-competitive inhibition and anti-competitive inhibition, respectively. The detail of the inhibition mechanism is described.

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Resonance Raman spectroscopy has the possibility of becoming a very promising analytical tool with both excellent selectivity and high sensitivity. The present investigation was conducted to obtain resonance Raman spectra of reactive substances with use of a capillary flow cell in stead of the rotating sample cell conventionally used. By passing the sample through the flow cell, the resonance Raman spectra were obtained for a wine red colored product formed by the reaction of 2, 4-dinitrophenylhydrazone (2, 4-DNPH) of aliphatic aldehydes with alkali solution. The capillary flow cell system was applied to detect eluents in HPLC. A mixture of aliphatic aldehydes-2, 4-DNPH (C₁C₅) was separated on analytical column (ODS, RP-18, 5μ, 3 mm i.d.×25 cm) and eluents were mixed with alkali solution in the Y type mixer on line and then introduced into the flow cell. Chromatogram was obtained by Ar ion laser (488.0 nm, 300 mW) monitoring at 1601 cm^-1. Calibration curve of formaldehyde-2, 4-DNPH was linear up to 2 μg. The lower limit of detection was 100 ng in 5 μl injection volume.

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An extraction procedure with isopropylether is used for the separation of gallium from interfering elements, and gallium extracted was determined fluorometrically by reaction with 2-hydroxybenzaldehyde-thiosemicarbazone (HBTS). The analytical procedure was as follows: 0.1 g of a sample containing (0.00010.02) % of gallium was dissolved by heating in 5 ml of hydrochloric acid (2+1). To the solution obtained, were added 0.1 ml of 20 % titanium trichloride solution and 5 ml of hydrochloric acid (2+1). Then gallium in the solution was extracted twice with 5 ml each of isopropylether by shaking for 1 min. After the aqueous phase was removed, the organic phase was washed 5 times with 2 ml each of hydrochloric acid (2+1) by shaking for 15 s. The organic phase was evaporated to dryness on a water bath, and the residue was dissolved in 1 ml of hydrochloric acid (1+100) and diluted to 10 ml with water. To an aliquot containing (0.15.0) μg of gallium, were added 0.2 ml of 1 % L-ascorbic acid solution, 2 ml of HBTS solution in DMF (Ga>1.0μg: 0.05 % HBTS, Ga<1.0 μg: 0.01 % HBTS) and 0.5 ml of 2 w/v % ammonium acetate solution. The pH of the solution was adjusted to 4.5 with 0.1 N hydrochloric acid or 0.1 N ammonia water, and the solution was diluted to 25 ml with water. The fluorescence intensity of the solution was measured (λ excitation 365 nm, λ emission 440 nm). The analytical results obtained by the proposed method were in good agreement with those by spectrophotometric method using PAN (LIS AO5_-1 1969). Accordingly, the proposed method could be applied to the determination of gallium above 0.0001 % in aluminum and aluminum alloys.

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A fluorometric micro determination of zinc by using 8-quinolinol-5-sulfonic acid (H₂QS) was described. The reagent reacts with zinc (II) to produce chelate anion. In the presence of trioctylmethylammonium chloride (Capriquat) a ternary complex is formed, which is easily extracted into chloroform phase. The extract has the excitation and emission maximum at 400 nm and 522 nm, respectively. Fluorescence intensity is constant over the pH range from 7.7 to 8.2, where the observed blank value is very low. The recommended procedure is as follows. To a sample solution containing (5.0250.0) nmol of zinc (II) are added 7 ml of 1 mM H₂QS solution and 10.0 ml of borate buffer (pH 8.0). The solution is diluted to 50 ml with water and shaken with 10.0 ml of 7 mM Capriquat-chloroform solution for 5 min and then allowed to stand for 30 min. The organic layer is transferred into a beaker containing anhydrous sodium sulfate to remove remaining water. Then, the fluorescence intensity of the extract is measured by means of a Shimadzu digital spectrofluorophotometer RF-510. The calibration curve showed a good proportionality in the concentration range from 5.0 nmol to 150.0 nmol. The effects of diverse ions on the determination of zinc were studied. In the determination of 70 nmol of zinc, twice molar amounts of cobalt (II) and nickel (II) gave negative errors, whereas twice amounts of cadmium (II) and aluminum (III) gave positive errors. One can eliminate the interference due to aluminum (III) by the addition of tiron.

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Trace amount of vanadium in river water was determined by the graphite furnace atomic absorption spectrometry using pyrolytic graphite coated tube after three coprecipitation treatments. Ferric hydroxide, hydrous titanium oxide, and the mixture of them were used as coprecipitation reagents. The recoveries of vanadium were nearly 100 % when used ferric hydroxide and hydrous titanium oxide at pH 6 to 9, and 4 to 8, respectively. Their C. V. % were 3.5 % and 3.4 % respectively. When used the mixed reagent of ferric hydroxide and hydrous titanium oxide, the recovery and C. V. % of vanadium were almost 100 % and 1.7 % at pH 4 to 8, respectively. Moreover, the total amount of reagent was reduced, and the precision of analysis was improved. The precipitate was collected by filtration with 0.45 μm millipore filter, and was digested with nitric acidhydrogen peroxide to reduce background absorption due to coprecipitated organic materials. To correct the background absorption due to coprecipitated inorganic salts, higher-brilliant thermal cathode type deuterium lamp was used. The sensitivity of this graphite furnace atomic absorption measurement using pyrolytic graphite coated tube was 10 to 20 fold than that of the measurements using uncoated tube or tantalum or tungsten carbide coated tube. Samples of Watarase river basin were determined for the investigation of water pollution by vanadium, and the satisfactory results were obtained.

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The effect of silicic acid on the coprecipitation of arsenic (III), arsenic (V) with iron (III) hydroxide has been studied. Silicic acid solution {(0.11.5) mg as SiO₂} was added to effect 10 μg/or 50 μg of arsenic coprecipitated with iron (III) hydroxide (1 mg as Fe) in 50 ml of solution. Silicic acid coprecipitated with iron (III) hydroxide reached a maximum amount at pH 89 on aging for 20 d, thereby causing desorption of arsenic. The amount of desorbed arsenic incrased with the concentration of silicic acid with time and then attained a limiting value after 20 d. In a solution containing silicic acid of pH 711, coprecipitation of arsenic decreased with increasing pH. In this pH range the amount of coprecipitated arsenic (III) was larger than that of arsenic (V). In silicic acid free solutions, the same phenomenon was observed in a pH region higher than 8, where iron-(III) hydroxide is negatively charged, but in this case the amount of desorbed arsenic was lessened. The difference in the behaviors between arsenic (III) and arsenic (V) can be explained as electrostatic interactions between iron (III) hydroxide and AsO₂^-, HAsO₄^2- and/or AsO₄^3-. On the other hand, silicic acid in a sample water interfered with preconcentration of arsenic, not only decreasing the coprecipitation efficiency but also making the subsequent filtra-tion slow and difficult. Iron (III) hydroxide brought down in the presence of an excess of silicic acid tends to be in very fine colloidal form. To avoid such colloidal precipitate formation, pH of the acidified solution was increased very slowly to pH78 In this way, flocks easy to filter could be obtained. The addition of H₂SO₄ to alkaline solutions was also effective in coagulation.

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In order to apply the Kováts' equation to partially methylated alditol acetates, we investigated the correlation between their molecular structures and retention indices from their relative retention times in gas-liquid chromatography. Many partially methylated alditol acetates were expressed in their numerical values based on two cardinal numbers, (fully methylated glucitol: 0, and fully acetylated glucitol: 100). Retention indices I and increment H were given by following equation:
I=100×log T_X-log T_M/log T_A-log T_M,
H=I_a-I_a, H_a=0.99×H_b+c.
We used 5 index units, three various methylated positions and two interactions. Relative retention times of acetates were obtained by calculation with several index units and by experiment on a column of 10 % SE-30/Chromosorb W (180°C and 210°C). Since we found the index units of the configurational contribution had additivity, it was possibe to apply the units to partially methylated alditol acetates. Using several calculated indices, we could presume a relative retention time of partially methylated alditol acetates which were difficult to synthesize. Moreover, it has become feasible to deduce the structure of unknown alditol acetates from their relative retention times.

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N-Methyl-2-pyrrolidone (MP) reacted with inorganic acids (hydrogen chloride, hydrogen fluoride) at reaction ratio of 1 to 1 to form colorless additive compounds. Dissolving ability of the additive compounds for metals, inorganic compounds and organometallic compounds was investigated, and metals in samples were determined by direct EDTA conductimetric titration after dissolution. MP·HCl and MP·HF were prepared by passing dried gas (HCl, HF) through MP at the rate of 30 ml/min. These additive compounds were stable in solid state and had relatively high melting points. Therefore the treatment of the reagents was easy to handle, and many metals and inorganic compounds were dissolved in them at comparatively low temperature without generating gases. When tin or titanium was dissolved in hydrochloric acid, it became a volatile metal chloride such as SnCl₄ or TiCl₄. But it formed a stable additive compounds with MP immediately in MP. The reaction equation was estimated as follows; Sn+4 MP·HCl→MP·SnCl₄+3 MP+2 H₂. Silicates (BaSiO₃, CaSiO₃, CdSiO₃, MgSiO₃, MnSiO₃, PbSiO₃, NiSiO₃, ZnSiO₃) were dissolved by the fluxes easily, too. As MP acid adducts had the both properties of organic solvents and inorganic acids, they were able to dissolve organometallic compounds. Determination of metals in organometallic compounds also could be carried out by EDTA conductimetric titration in DMSO, after dissolved the samples with the additive compounds. And organometallic compounds were indirectly determined from the measured amounts of metals.

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Silicic acid in water was effectively sorbed on anion exchange resin of molybdate form, and silicomolybdate formed on the resin. When the resin having sorbed silicic acid was immersed in a reducing agent solution, it colored blue. The color intensity of the resin phase was proportional to the concentration of the silicic acid. The anion exchange resin of molybdate form was prepared by immersing anion exchange resin {Dowex 1×8 of chloride form, (100200) mesh} in ammonium molybdate solution, and drying under reduced pressure. Procedure; Add 0.50 g of the resin into 25 ml of water sample (pH39), and stir for 20 min. Discard the solution and add 10 ml of reducing agent solution (ascorbic acid; 1 %, antimonyl potassium tartrate; 0.01 %, sulfuric acid; 0.1 M) to the resin, and stir for 20 min at 25°C. Discard the solution and wash the resin with water. Transfer the colored resin slurry into a 1 mm cell with water, and measure the absorbance at 700 nm against reagent blank. When 25 ml of the silicate solution was treated with 0.50 g of the resin, up to 50 μg of silicon was determined. The coefficient of variation of this method was 3.39 % for 12 silicate solutions each containing 1 ppm silicon. When 25 ml and 250 ml of silicate solutions, each containing 50 μg of silicon, were treated with 0.50 g of the resin for 60 min, the ratio of absorbances was found to be about 2 to 1. Since the color intensity was affected to a considerable extent by the particle size of the resin, the resin should be sized within narrow range. The method was applied to the determination of silicic acid in water samples.

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Electrochemical characteristics of a flow-through electrolytic cell which is mounted as a working electrode composed of reticulated vitreous carbon (RVC) are described. The RVC has low electrical resistance, large surface area, and a physicall continuous-structure. At constant potential, the analyte solution was pumped through the electrode at a constant rate, generating a steady-state current. The steady-state current and the degree of electrochemical conversion were extremely dependent on the flow rate and the electrode length. Also, the current was linear with respect to the concentration of hexacyanoferrate (III).

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Fluorescence reaction of ammonia with fluorescamine (FL) in a mixed solvent of water-acetonitrile-acetone (1:9:10) was found. On the bases of this reaction, a fluorometric determination of ammonia has been developed. Two milliliters of a sample solution dissolved in 90 % acetonitrile is added to 2 ml of acetone solution of FL. The mixture is heated for 30 min at 50°C and cooled to room temperature. The fluorescence intensity of the solution is measured at 470 nm with excitation at 380 nm. The calibration curve was found to be linear in the range of 0.01 μg/ml to 1.0 μg/ml.

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Rapid determination of trace elements in various types of oils diluted with an organic solvent is investigated by inductively coupled plasma emission spectrometry. The sample introduction system of the conventional typical torch was modified, and the optimum operating conditions for the introduction of the diluted oil samples were obtained. Either commercially available blended standard oils diluted with MIBK or organometallic reagents dissolved in MIBK containing the matrix oil could be used as the standard for the calibration. Nickel and vanadium in standard heavy oils were determined after 10-fold dilution with MIBK, and the results were in good agreement with the certified values. Trace phosphorus and silicon in edible oils could also be determined. The effect of sample viscosity on introduction rate into the plasma was negligible in this method. Although, the complete recovery of the elements was not obtained for lubricating oils containing gross particulates of wear metals, the precision was fairly better than that obtained in atomic absorption or rotating electrode spark emission spectrometry. Thus, the proposed method is effective for the check of the concentration change of the specified element in used lubricating oils.

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The gas chromatographic determination of trace amounts of dimethyl trisulfide in air and in exhaust gases from some odor sources such as kraft pulp factory and poultry manure dryer was investigated using two preconcentration methods, namely, the cold trapping with liq. Ar and the adsorption trapping with a porous polymer beads such as Tenax-GC at room temperature. The conditions for the gas chromatography of the sample gas were as follows: main analytical column packing; 25 % 1, 2, 3-tris-2-cyanoethoxy propane (TCEP) on Shimalite, AW, DMCS, 60/80 mesh, column size; 3 m×3 mm i. d., glass, column temperature; 70°C, carrier gas nitrogen flow rate; 50 ml/min, precolumn packing; for the cold trapping; 25 % TCEP on Shimalite, AW, DMCS, 60/80 mesh, column size; 31 cm×4 mm i.d., glass, for the adsorption trapping; Tenax-GC, 60/80 mesh, column size; 16 cm×4 mm i.d., glass, detector; flame photometric detector (FPD), respectively. The cold trapping was operated at liq. Ar temperature (-186°C), and the temperature was elevated to 120°C for 3.5 min in carrier gas, and maintaining this temperature for 1 min for injection of the condensed sample into gas chromatograph. The adsorption trapping was operated at room temperature (25°C), and the temperature was elevated to 250°C for 35 s in carrier gas, and maintaining this temperature for 30 s for injection of the condensed sample into the gas chromatograph. The response (peak area, as the counts of a digital integrator) of the FPD to dimethyl trisulfide was linear in the range of 10 ng to 200 ng. The minimum detectable quantity of dimethyl trisulfide was about 0.5 ng at twice noise level; therefore when the preconcentration volume was 1 1, the minimum detectable concentration was about 0.1 ppb. The analytical precision was 12.0 % for the cold trapping method, and 6.0%for the adsorption trapping method in the coefficient of variation. The maximum concentration volume for quantitative data in the adsorption trapping method was about 4001, and the loss of the contents of the adsorpted dimethyl trisulfide on the adsorption trapping precolumn (Tenax-GC) was not recognized until the standing time of 88 h. The detected concentration ranges of the dimethyl trisulfide in the ambient air over the waste water and in the discharged gas from the recovery furnace of the kraft pulp factory was 17.8 ppb to 193.2 ppb; and that in the exhaust gases from two poultry manure dryers was 0.4 ppb to 74.1 ppb, respectively.

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