A method is described for the preconcentration and determination of the traces of Ag, Bi, Co, Cd, Cu, Fe, In, Mn, Ni, Pb, and Hg in sodium perchlorate. The samples of 100 g of NaClO₄. H₂O were dissolved in 200 ml water and the solution was filtered through a small filter paper coated with 50 mg of activated carbon, after the adjustment of pH to 6.0 (the pH was not adjusted for the Hg preconcentration). The trace metals of the concentration ranging from O.3 to 200 ppb and 0.012 to 2.0 ppb of Hg were quantitatively adsorbed on the activated carbon. The activated carbon (with exception for the procedure of Hg) was treated with 1 ml of the concentrated nitric acid to liberate the adsorbed traces and the solution was evaporated to dryness. Then the residue was dissolved in 3 ml of 20% nitric acid and the trace metals were determined by the flame atomic absorption spectrometry (AAS). The concentrations of Hg adsorbed on the activated carbon were determined by the flameless AAS, the activated carbon and the filter paper being together heated at 500°C for 5 min and the mercury being atomized. The detection limits for the analysis of 100 g of NaClO₄. H₂O were 0.012 ppb for Hg, 44 ppb for Fe, and 0.3∼7 ppb for the other elements. When 0.016 μg of mercury (II)chloride was dissolved into 200 ml of the distilled water in a beaker and stood for 24 h at 17°C, about 30% mercury was adsorbed on the glass wall. However, the, adsorbed amounts of mercury decreased by the addition of sodium perchlorate and no appreciable adsorptions occurred in the sodium perchlorate solutions of the concentrations more than 0.14 molidm^-3.

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In the determination of manganese in sea water by graphite furnace atomic absorption spectrometry, several metals, especially alkali, alkali earth metals, aluminum, iron and zinc, show severe background absorption and interferences. These interferences varied with the charring temperature and can not be excluded in the charring step at 900°C. To suppress these interferences, the matrix modification was been investigated, i. e., the matrix is changed into the harmless form by the addition of proper reagent in the graphite furnace. Effect of added ascorbic acid and its related compounds, carbon powder, and ammonium nitrate was studied against the interferences of sodium chloride, calcium chloride and sea water. L-Ascorbic acid was found to be the best among them the suppression of interferences in sea water was realized by the addition of 20 μl of 5% ascorbic acid against 20 μl of a sample. The sample was injected using an autosampler into the graphite furnace to improve the precision. In the injection of ascorbic acid, a micropipette was employed. The C. V. (n = 10) of determinations for the standard solution and the sea water was 2.8% and 6.1% respectively in the presence of ascorbic acid. This method was applied to the direct determination of manganese in sea water. The results gave a good agreement with those of the standard addition method, and the precision was improved to within 12%.

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A simple method has been developed for the determination of trace copper by atomic absorption spectrometry. The method is based on the direct atomization of metal-adsorbed ionexchange resin in a graphite furnace. A comparison of ashing behavior with respect to the type of ion-exchange resin, such as Amberlite IR-120 B, IR-122, IR-124, Dowex A-1 and Sephadex SP-25, was made, and the first one was found to be most suitable for the present purpose. Aspects investigated include ashing and atomizing conditions, elimination of interferences from the peak o. and sensitivity.
Uniform particles of the resin in th e hydrogen form (W g, above 20 mesh) were put into the test solution (Vl) of the metal ion concentration Co, and the resin was separated fr om the aqueous solution and dried. Without weighing, one particle of resin (w g, ca.0.6 mg)was placed onto the diluted poly (vinyl alcohol) solution (15μl) which was pipetted into the graphite furnace, and the atomic absorption peak signals were measured. The absorbance due to the metal is theoretically proportional to VwCo/W. The optimum furnace conditions and the experimental results are shown in Table 2 and 3. The matrix effects from ashing resin are not observed. This method made it possible to determine a very low concentration of copper, and the relative standard deviation was 4∼7% at 0.01 ppb level.

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For direct determination of heavy metal ions at ppb level by graphite furnace atomic absorption spectrometry (GFAAS), spontaneous preconcentration of these ions onto the surface of metals with high melting points such as tungsten, molybdenum, tantalum and rhenium ha s been studied. Effect of experimental parameters such as soaking time, chemical pretreatment of metal wires, pH and temperature of the sample solution on the absorbance gignal was investigated. This approach was found to satisfy required conditions for an analytical metho d, because a quite good linear relationship was obtained between the absorbance signal an d soaking time of metal wire or the concentration of sample solution in a limited concentration r a nge peculiar to the analyte ions.
Taking the preconcentration ability of heavy metal ions, chemical stability against acids and bases, durability and melting points into consideration, tungsten, molybdenum and rheniu m wire showed a good property in this method and tantalum wire was inferior to other t hree in the preconcentration ability. The main mechanism of preconcentration of heavy metal ion s onto tungsten and molybdenum was supposed to be cation exchange reaction with hydrat e d oxides present on the metal surface. As a result of investigation by X-ray diffracto m etry, however, Ag⁺ and Cu⁺² were preconcentrated by the deposition of these ions in metallic state in addition to cation-exchange reaction. Preconcentration of Pb" occurs by the formation of compound such as PbWO₄ or PbMoO₄.
As an example of the applica t i o n of this analytical technique to practical samples the determination of copper in sodium nitrate was carried out. The results obtained agreed well with those obtained by the solvent extraction method. This method is considered to be suitable for the determination of trace amount of heavy metal ions in simple solutions such as river wat e r or alkali salt solutions.

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The trace amount of vanadium in sea water was determined by graphite furnace atomic absorption spectrometry with a tube coated with pyrolytic graphite (see Fig.2-2) after a preconcentration treatment described as follows. Three methods were employed, an anion exchange-solvent extraction method, a chelating exchange method and a coprecipitation method. To correct the background absorption, a deuterium lamp with a higher-brilliant thermal cathod was used. The sensitivity for vanadium increased 10∼20 fold by the use of the tube coated with pyrolytic graphite (see Table 5), and the utility lifetime of the tube was greatly extended.
Vanadium (V) 4- (2-pyridylazo) resorcinol (PAR) complexes were extracted into chloroform as an ion-pair with benzyldimethyltetradecylammonium (Zephiramine) cation alternatively. But salts in sea water considerably interfered and the extraction ratio deteriorated. Then in order to separate the interfered ions, anion exchange was carried out before the extraction treatment. The sample of sea water, which was made to 0.1 N in sulfuric acid and 0.1% in hydrogen peroxide, was loaded onto the column of Dowex 1-X 4 resin (SO₄^2--form). Vanadium was then eluted from the resin with I N sulfuric acid-0.1% hydrogen peroxide or 1 N hydrochloric acid-0.1% hydrogen peroxide, and the elute was collected and evaporated to dry. A fter dissolulion of the elute in 0.2 N nitric acid, vanadium was extracted.
Secondly, a chelating exchange was conducted. The sample of sea water was adjusted to pH 5.0, and loaded onto the column of Chelex-100 resin. Vanadium was then eluted from the resin with 2 N ammonia and the elute was collected in a volumetric flask (50 ml).
The above two methods took much time, but the coprecipitation method was not so and recommended for the determination of vanadium in sea water. Vanadium was coprecipitated with iron(III) hydroxide-hydrous titanium (IV) oxide at pH 6.0. The precipitate was filtered and was digested with nitric acid-hydrogen peroxide to reduce the background absorption due to the coprecipitated organic materials. The solution was diluted to 50 ml with water in a volumetric flask.
The result ing solutions were employed to determine the vanadium concentration by the graphite furnace atomic absorption measurement. The good agreement was obserbed between the results obtained from the three preconcentration methods, and vanadium concentrations were ranged from 1.0 to 1.5 ppb in the Indian Ocean and the Pacific Ocean (see Table 3). And the trace amounts of vanadium in various kinds of the coastal sea water were determined by the coprecipitation method (see Table 4).

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In low-polluted environmental samples such as (atmosphere, fresh water, solid sample including rock and, biological material in a dried condition), their mercury contents are very low, being as little as ppb or sub ppb level. Thus it is very difficult to obtain precise and reliable results on them (Fig.1). Analytical method for mercury in such samples was carefully checked and examined. As the results the determination of ultratrace amounts of mercury is strongly recommended to proceed in the following way.
(1) The separation and concentration of mercury from the atmosphere, prior to cold vapor atomic absorption spectrophotometry, should be carried out by allowing the mercury to be trapped on a carrier covered with porous gold.
(2.) If possible, the separation of mercury from the solid sample should be performed physically e. g. by heating at high temperature to avoid any contamination of mercury from chemicals. The concentration and accumulation of mercury evolved from the solid sample should be carried out by trapping it on a porous gold in the same way as described (1).
(3) Mercury in water samples should be reduced to elementary mercury by using tin (II)chloride, evolved by aeration and then collected on a porous gold. After. these treatment, the mercury is evolved by heating the collector at ca.700°C and determined by cold vapor atomic absorption spectrophotometry.

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Atomic magneto-optical rotation spectrometric apparatus using the atomic Faraday effect was combined with the electrothermal atomization equipment and applied to the determination of traces of Au, Mn, Co and Ni. A graphite tube atomizer was attached to the pole pieces of an electromagnet, which magnetized the atomic vapor evolving in the atomizer. As a result, the source radiation could pass through two plane-polarizing prisms in a crossed configuration. The dependence of the transmitted intensity on the magnetic field strength was studied and related to the theoretically calculated Zeeman splitting pattern. New line-crossings between σ +and σ - components were recognized in the analytical line of Au (242.795nm). However, the complete agreement could not be obtained between the theoretical and experimental results. In a region of magnetic field strength from 4.5 to 8.0 kG, the transmitted intensity exhibited a maximum value. This is defined as the optimum condition of magnetic field strength.
The calibration graphs revealed that the transmitted intensity(I⊥) depended on the square of the amount of elements. With hollow cathode lamps, the present technique gave detection limits of 50, 2, 20 and 17 pg for Au, Mn, Co and Ni, respectively, and was applied to the trace determination of Mn in a volcanic ash sample.

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Simultaneous multielement analysis of waste water was investigated by inductively coupled plasma emission spectrometry (ICP-ES). The waste water samples, which were collected at each section of the University of Tokyo, were digested with nitric acid and sulfuric acid. Simultaneous multielemnt determinations of 22 elements listed in Table 2 were examined. The preparation of standard solutions, the measurement conditions, and the effects of acid concentrations were examined as well. The optimum measurement conditions were determined so as to obtain the higher signal-to-background ratios (SBR) of 8 analytical lines listed in Table 3. Figs.1, 2 and 3 indicate the dependences of SBR of several analytical emissionlines on the operating conditions of the plasma. Consequently, high SBR was obtained at the following conditions; 0.78 4min carrier argon flow rate, 1.1 kW RF power and 17 mm of observation height above load coil. The influence of sulfuric acid concentration on the introduction rate of sample solution to the plasma was crucial and it was necessary to match the acid, concentration of standard solutions to the samples. The accuracy of the present method was examined for Fe, Zn, Cu and Cd with flame atomic absorption spectrometry, which is currently used for the ordinary waste water analysis. The results were in good agreement with those by ICP-ES. The data obtained by ICP-ES were summarized in Fig.8 to illustrate the distribution of the concentration of some elements in the waste water. The present experiment revealed that ICP-ES is a very useful method for the monitoring of waste water in the points of high sensitivity, high accuracy and the rapidity of analysis.

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The ultra-trace analysis of pyrene has been carried out in methanol on the basis of timeresolved laser fluorometry. The signal-to-noise (S/N) ratios were calculated for the individual observed points on the fluorescence spectrum, and the improvement of the SIN ratio by the time-resolved detection was discussed. Very low concentrations of pyrene as 2×10^-12m ol/l (0.5ppt) was determined, since the background signal from the solvent and impurities could be removed by using a double monochromator and gated operation of the detection system (dalay time; 30 ns). The minimum detectability was limited by contaminant fluorescence of pyrene adsorbed on the wall of the sample cell, which could not be washed out by any practical method (surfactant, chromic acid mixture, alkali-ethanol etc. ). Coexistence of 1×10^-9 mol/l benzo [ a ]pyrene did not disturb the determination of pyrene.

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A highly sensitive fluorometric determination of 10^-9gcm^-3 level of magnesium (II) was carried out by using water-soluble porphyrin, α, β, γ, δ-tetrakis (1-methylpyridinium-4-yl)porphine (TMPyP). Mg-TMPyP complex has highly intense red flu orescence, compared with that of the reagent, TMPyP. The ratio of relative fluorescence intensity, Mg-TMPyP/TMPyP was 47.6, where the wavelength of excitation was 451 nm and that of emission was 641 nm. TMPyP reacted with magnesium (II ) ion to form a green complex over the pH range 9.1∼10.6. The complexation was very slow even under a boiling conditions, but it was accelerated by addition of 4×10^-5 to 2×10^-4moldm^-3 of 8-quinolinol (oxine) to the reaction system and was completewdi thin6 0m inutebs oiling. Manym etali onsi nterferetdh e determinatioonf m agnesium(1J) (Table 2), but most of them, except Cr⁺³, were selectively extracted into CCl₄ as their dithizonato complexes. Then magnesium (II ) can be selectively determined by the following procedure; take an aliquot (not more than 20 cm3) containing up to 2 μg of Mg.⁺² into a 50 cm3 Erlenmeyer flask. Add 2.5 cm3 of 10^-3 of 10^-3 moldm^-3 oxine solution and 1cm3 of 10^-4m oldm^-3 TMPyP solution, and adjust it to pH 9.1∼10.6 with 1 cm3 of 0.1 moldm-^-3 borate-sodium hydroxide buffer solution. Immerse the flask in a boiling water bath for 60minutes and allow it to cool to the room temperature. Transfer the solution to a 25 cm3volumetric flask, and dilute it to the mark with water. Measure the fluorescence intensity at 641 nm with excitation at 451 nm.
The calibration curve is lin ear over the range Mg²⁺ 0∼1.94 p g/25 cm3. The coefficient of variation was 1.22% for Mg²⁺ 0.24, μg/25 cm3 (10 determinations). Results are quoted for the application to the determination of Me²⁺ in calf serum.

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Several europium and samarium β-diketonates (tta, ntfa, bfa) complexed with 1, 10-phenanthroline, or with trioctylphosphine oxide (topo) were synthesized. The fluorescence propertiesof these compounds in benzene or hexane have been studied. Absorption and fluorescence spectra, fluorescence quantum yield, fluorescence sensitivity index (F.S.I.), and fluorescence lifetime were measured. From the measurment of fluorescence lifetime of the β-diketonates, the velocity of radiative process (k_f/φ_f) has almost the same value for benzene and hexane solvent. The red fluorescence (Em. max.: 619 nm) of Eu(III) in these chelates is attributed to transitions from ⁵D₀→.⁷F₂ levels of this ion, and the three-band spectrum (Em. max.: 569 nm, 606 nm, 650 nm) indicates the transitions from the ⁴G_5/2→.⁶H_5/2, ⁴G_5/2→.⁶H_7/2, and ⁴G_5/2→.⁶H_9/2 levels of Sm (III), respectively. These spectra are not changed by any solvents and ligands. From the results, the fluorescence of the β-diketonates in organic solvent has been attributed to m→m luminescence transition. The complexes of Eu (III) and Sm (III) show radiative transition within orbitals, composed exclusively of 4f orbitals of rare earth ions (m*→m radiative transition).
Fluorinated ligands show better sensitivity than unfluorinated ligands, and the best sensitivity is obtained with TTA-phen system, and/or TTA-topo system for the spectrofluorometric determination of the two metals. In the case of Eu determination, 619 nm emission wavelength is used (the determinable range: 0.2∼10 ppb Eu), and in the case of Sm determination, 650 nm emission wavelength is adopted (the determinable range: 0.1∼1 ppm Sm), because of much higher sensitivity than the other two peaks (569, 606 nm) without interference from europium complex.

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The utility of electrogenerated chemiluminescence (ECL) for an analytical purpose is described. As the ECL analysis uses a certain type of electrolysis for the observation of chemiluminescence at the electrode surface, a proper selection of the applied potential region and the frequency of square wave allows us to determine selectively a desired trace component in the presence of other major components. The basic experimental procedures have now been established for a model system of a mixture of substituted anthracenes 9, 10-dicyanoanthracene (DCA), 9, 10-diphenylanthracene (DPA) and 9, 10-dipropylanthracene(DPrA ). By fixing the negative side of the applied square-wave potential at the reduction potential of DCA, the positive potential was swept linearly to the positive direction. The chemiluminescence was observed above the oxidation potential of DPrA and DPA. The electron transfer reaction was thus shown to be possible between anion radicals of DCA and cation radicals of DPrA or DPA. As the ECL spectrum coincides with the fluorescence spectrum of DCA, the triplet-triplet annihilation reaction of excited state of DCA is considered to be responsible for the emission. From a viewpoint of analytical determination, it is interesting to detect a trace am ount of DPA in the presence of large quantity of DPrA because of a similar fluorescence spectrum of both compounds. By choosing a suitable experimental condition of ECL, it is possible, for example, to determine 0.2μmol/l of DPA in the presence of 0.2 mmolg of DPrA.

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The effect of methyltrioctylammonium chloride (Capriquat) on the extraction of dithizonatopalladium(II) was studeid. The addition of Capriquat to the extraction system not only accelerates the extraction, but enhances the extractability of Pd(II) by so-called synergistic effect. Moreover, the use of this reagent favors the rapid and quantitative extraction from a strongly acidic solution as well as the preferential formation of the reddish complex [Pd(dz)]. The effects made it possible to establish a highly sensitive spectrophotometric method for the determination of Pd(II) using the above dithizonate. The proposed procedure is as follows: Take 9.6 moldm^-3 hydrochloric acid solution containing up to 25μg of Pd(II) in a separatory funnel, add 10.0cm³ of chloroform solution of 0.001% dithizone plus 5.0% Capriquat. Then shake the mixture for 5 min and allow to stand for 120 min in order to attain the quantitative formation of Pd(dz). Measure the absorbance of the organic phase at 530 nm., against the reagent blank. The sensitivity of the method is 0.0060μgcm^-2. Effect of some diverse ions was also studied 10 μg of Cu (II), 100μg of Co (II), 1000 μg of Zn(II), Hg(II), Pb(II), or Sn(II) did not interfere with the determination of Pd(II).

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A highly sensitive catalytic method is proposed for the determination of iron. This method is based on the catalytic effect of iron (III) on the oxidation of Variamine Blue B leuco base analogue, N-(p-methoxyphenyl)-N', N'-dimethyl-p-phenylenediamine (MDP). MDP is formed by the reaction of p-anisidine with N, N-dimethylaniline and catalytically oxidized to a blue compound, N-(p-methoxyphenyl)-N', N'-dimethyl-1, 4-benzoquinone diiminium ion (MDB)(λ_max= 735nm) by trace amounts of iron (III) in the presence of hydrogen peroxide. The reaction is extremely accelerated by 1, 10-phenanthroline as an activator. By this catalytic effect, ultratrace amounts of iron (III) can be determined. Iron (II) is also determined, being oxidized by hydrogen peroxide. The color development was at a maximum and almost constant at pH 3.6∼3.7. The reaction proceeded faster at higher temperatures, but the decomposition of MDB became more extensive above 55°C. For the anisidine concentration of 2.5×10^-3mol⋅dm^-3, the absorbance remained constant over the range 0.5×10^-2-1.3×10^-2mol⋅dm^-3 N, N-dimethylaniline. A constant absorbance was obtained over the range 5.0×10^-2-9.0×10^-2mol⋅dm^-3 hydrogen pewxide. Higher sensitivity could be attained by adding 1, 10-phenanth roline. The linear working curve was obtained in the presence of 1, 10-phenanthroline, but not without 1, 1 0-phenanthroline. Oxidizing ions such as cerium (IV), chromium (VI) and vanadi um (V)caused seridus positive interferences. Negative interferences were observed from cobalt(II), nickel (II), zinc (II), molybdenum (VI), tungsten (VI), tin (II), tin (IV), fluoride and phosphate. The method is highly sensitive with a Sandell sensitivity of 1.O×10^-2ng⋅cm^-2 and allows the determination of ppb level of iron in tap water with satisfactory results.

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A new, sensitive and selective catalytic method is proposed for the determination of copper. The reaction of the method is as follows: p-anisidine reacts with N, N-dimethylaniline to form Variamine Blue B leuco base analogue, N-(p-methoxyphenyl)-N', N'-dimethyl-p-phenylened iamine (MDP). MDP is probably oxidized to a blue compound (MDB) by trace amounts of copper(II) in the presence of hydrogen peroxide. In this reaction, ammonia and acetic aci d act as activators. The color development was maximal and constant in the pH range 3.8∼4.1 at 60°C for 10 min, decreasing on both sides of this range. For the 4.0×10^-2mol⋅dm^-3 anisidine concentration, a constant absorbance was obtained over the range 6.5×10^-3∼1.1 ×10^-2moldrn^-3 N, N-dimethylaniline. The rate of the color development tended to increase w ith increasing concentration of ammonia and acetic acid. The rate of the color development also increased with increasing concentration of hydrogen peroxide, but a constant absorbance w as obtained over the range 8.0×10^-2∼1.44×10^-1mol⋅dm^-3 hydrogen peroxide. The reproducibil i ty of the method proposed was satisfactory with the relative standard deviations of 2.3, 1.7 and 1.2 % for five determinations of 0.1 0, 0.2 0 and 0.50μg copper (II) per 50 m l of the react ion mixture, respectively. Only iron (II ), iron (III), chromium (VI) and tin (IV) showed serious interferences in this method. The interferences from iron (II) and iron (III) could be supp ressed by adding sodium fluoride. The method was successfully applied to the determination of copper in tap water. The method is simple, selective and sensitive: as little as 10^-8mol⋅dm^-3 of copper can easily be determined.

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A sensitive and simple method has been developed for the determination of trace vanadium by means of flow injection analysis based on the catalytic oxidation of Bindschedler's Green leuco base (4, 4'-bis (dimethylamino)diphenylamine, BGL) by potassium bromate.
A schematic diagram of the flow injection system is shown in Fig.1. The reagent solutions of BGL and potassium bromate in reservoirs A and B, respectively, were pumped out using a peristaltic pump into the manifold. A sample solution, 20μl, was introduced into the carrier reagent solution via syringe loading sample injector. The introduced sample was then transported through the reaction coil (poly (tetrafluoroethylene), inner diameter 0.56 mm), and BGL was oxidized to Bindschedler's Green (BG) which showed a maximal absorbance at 725 nm. The absorbance of BG was monitored at 725 nm by spectrophotometer equipped with a flowthrough cell (volume 200μl, light path 5 mm), and was continuously recorded. Some factors that influence the flow injection system, pumping rate, reaction coil length, sample volume and sampling rate, were studied systematically.
Under the conditions of BGL: 1.6×10^-3molg, potassium bromate: 6.4×10^-2mol/l, pH: 3.8and temp.: 25°C with pumping rate 1.6 milmin and reaction coil length 5 m, a liner relationship was obtained between the peak height (absorbance)and the concentration of vanadium (IV)in the range of 0∼80 ppb. In this method, the detection time after sample injection was ca.40 s, and a sampling rate of 60 samples/h was achieved.

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Various substoichiometric methods have been classified from a view point of the substoichiometric separation. Based upon the substoichiometric separation, phosphorus was determined substoichiometrically by a direct method, a method of carrier amount variation and a comparison method for the irradiated sample. The direct method was applied to the determination of phosphorus in orchard leaves (SRM-1571). The analytical value was 0.23±0.01%. Phosphorus in orchard leaves and spinach (SRM-1570) was determined by an ordinary method which devided the sample into equal parts in the method of carrier amount variation. Analytical values of orchard leaves and spinach were 0.22±0.02% and 0.56±0.04%, respectively. Moreover, a new modification of the method of carrier amount variation was studied by the use of various standard samples such as red phosphorus, spinach and orchard leaves. These standard samples were also employed for the determination of phosphorus in orchard leaves and 0.21±0.01% was obtained. All these results are in good agreement with the value reported by NBS. The comparison method was applied to the determination of phosphorus in a semiconductor silicon single crystal. As a result of the Correction of ³²P activity induced by the secoundary nuclear reaction of ³¹Si, 7.9 ppb and 3.1 ppb were obtained for the phosphorus concentrations in the single crystal silicon.

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A simple method is presented for the determination of mercury in rocks, sediments and plankton. After irradiating a sample by thermal neutron, it is directly heated in strong phosphoric acid (SPA) containing sodium bromide without any other treatment to evolve mercury as mercury (II) bromide. The distillate is absorbed in distilled water, in which mercury is later precipitated in sulfide form by adding thioacetamide and standing for digestion. The precipitate is filtered through a glass fibre filter paper, washed with distilled water and ethanol and dried at 105°C. It is shielded with cellophane tape and submitted to T-ray spectrometry by Ge (Li) detector coupled with a 1024 channel pulse height analyser. For mercury(II) chloride, oxide, sulfate and sulfide, mercury (II) bromide can be evolved with NaBr-SPA reagent, but only about 60% of mercury is evolved from mercury ( I ) compounds.. However, the latter species is found to be perfectly distilled with NH₄V0₃-NaBr-SPA. Among the several nuclides distilled with mercury, ⁷⁵Se is an only element that interferes the determination. This nuclide can be separated from ²⁰³Hg by adding a small excess of sodium sulfide to a reaction flask, which contains mercury (II) carrier solution in order to convert it into sulfide from. During distillation some sulfide decomposes and liberates free sulfur which coprecipitates ⁷⁵Se nuclide in the absorption solution. "Se can be filtered off from mercury. Two ng of mercu ry can be determined within a error of ±5%. The application of the proposed separation method to flameless atomic-absorption spectrometry is also discussed.

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A new method for the determination of ²²⁶Ra, ²²⁴Ra and ²²⁸Th in water samples is described. It consists of extraction of 222Rn and ²²⁰Rn into a scintillator-toluene solution in equilibrium with ²²⁶Ra and ²²⁴Ra and the application of integral counting techniques with a liquid scintillation counter. One liter water sample, weakly acidified with hydrochloric acid, is transferred to a glass bottle, and vigorously bubbled with a stream of nitrogen to expel any radon or thoron in the water sample. Twenty five ml of the scintillator-toluene solution is added to the bottle (time is recorded). The bottle is stoppered with a Teflon stopper and kept at an upside-down position for a given period of time (usually 4∼16 days) to allow radon and thoron in partial equilibrium with their parent nuclides. Then, the sample system is vigorously shaken for 2 m and the organic layer is gently transfered to a counting vial through a specially devised transferring tube which is connected to the bottle. The initial counting time is set at 4 h after the separation of organic layer. The measurements are repeated 3 times each immediately and after 106 h from the initial counting time. From these results, the integral counting rates of radon and thoron at the initial counting time are easily obtained. The activities of ²²⁶Ra, ²²⁴Ra and ²²⁸Th in the water sample are calculated from these integral counting rates by the proposed formulas. Some data on the ²²⁶Ra and ²²⁴Ra contents of mineral springs are presented.
The lowest detection limits for ²²⁶Ra and ²²⁴Ra were 1.10×10^-12 and 1.47×10^-9 Ci, respectively. The present method is rapid, easy and accurate and eliminates a time-consuming sealing of the sample in Curie bottle and tedious procedure to transfer the sample gas through a vacuum system to the detector.

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Isotope dilution-surface ionization mass spectrometry, IDMS, using a quadri-spike solution of ²⁰³T, 1 ⁶⁵Cu, ¹¹⁶Cd and ²⁰⁶Pb, h as been developed to determine ultra-micro amounts of thallium, copper, cadmium and lead in reagents and water purified by sub-boiling distillation. A single filament of rhenium was used as an ion source in a Hitachi RMU-6-Type Mass Spectrometer, a mixture, solution of phosphoric acid and silica gel being added to a sample as a stabilizer for the ion emission. The present method has the following detection limits, Tl (10^-13 ∼10^-15g), Cu (10^-11∼10^-13g), and Pb (10^-12 ∼10^-13g), and the precision is usually better than 1% in the coefficient of variation for the determination of isotopic ratios. This means that the method can be applied' to the determination of these elements at the level of ng with an effective figure of 2. This method revealed with its excellent sensitivity and accuracy that commercial high-purity reagents (HCl, HNO₃, HF, HCIO₄, H₂SO₄, aq. NH₃, CH₃COOH and C₂H₅OH) and water were furthermore de-mineralized to the level of ppt by sub-boiling dis tillation using quartz and Teflon stills.

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A clean analytical system and sampling procedures have been developed for accurate measurements of background atmospheric concentrations of halocarbons (CCl₂F₂, CCl₃F, CCl₂FCCl1F₂, CH₃CCl₃, CCl₄, CHCl, CCl₂, CCl₂, CCl₂), some of which are suspected to be the cause of the depletion of stratospheric ozone. Atmospheric samples were collected in all-stainle ss steel canisters evacuated to 10^-4 Pa at 200°C. The composition of the samples was not altered during a long term storage, while heavy contamination was inevitable with other conventional sampling techniques used in most air pollution studies. Calibration standards (30 to 300 ppt)were prepared carefully by a four-step static dilution method using an extremely clean vacuum line and purified zero air. A Silicone OV-101 column was used as the preconcentration and separation column with the temperature programed from -40°C to 70°C. Methane (5%) was mixed into nitrogen carrier gas as a make-up gas for ECD to improve the S/N ratio and stabilize the baseline without reducing the sensitivity. The contamination from the analytical system was below the detection limit. Concentration measurements were reproducible within 1%. The absolute accuracy was estimated to be 6% of the observed value plus 5 ppt. The atmospheric concentrations of halocarbons were measured in the summer of 1979 and the winter (Jan.∼Feb.) of 1980 in remote areas in Japan.

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Analytical performances of our new ionization detector (Liquid ionization detector) developed recently have been investigated for detecting trace organic compounds in solution.
By applying negative voltage to a needle electrode for the Corona discharge, the sensitivity of the detector was increased about 10 times as compared to that obtained by applying positive voltage (Table 3). The measuring sensitivity appeared to increase with decreasing ionization energy and increasing molecular weight and boiling point of the monitored compound when measured at the optimum heating conditions (Tables 2 and 3). However, the sensitivity for involatile compounds (for which boiling point are unmeasurably high) such as D-glucose was smaller by anorder of magnitude than that for compounds with high boiling point. The peak area (total ion abundance) of a less volatile compound was found to be almost constant at high heater currents, while too much heating resulted in decrease of ion abundance for more volatile compounds (Figs.2 and 3). It was also confirmed that the temperature at which the top of the peak of a solute such as glucose appeared was almost constant, regardless of the heater current, and that the peak height (maximum ion current) depended on the surface area of a sample solution on the sample holder (Fig.4). By using this detector a nd water, acetonitrile or Freon 113 as a solvent, it was possible to detect 0.1∼10 ng (0.1∼10 ppm as concentration) of organic compounds in general (e. g.1-butanol-sucrose). When the surface area of a sample solution and the heating conditions were kept constant, good linearity was observed between the response (peak height and peak area) of a solute and its concentration in the range 0.002∼0.5 wt% (Fig.5).

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Fourier transform infrared reflection absorption spectrometry has been applied to quantitative analysis of organic materials on the surface of industrial aluminum plates. The surface of aluminum was roughened (roughness value R_s = O.9 and 1.3) or anodized so that the abundance of alminum oxides might be 0.3 mg/cm2 (AD 30) and 0.1 mg/cm2 (AD 10). Poly (methyl methacrylate) (PMMA) was chosen as an organic material and the reflection absorption method was used as an example of a photosensitized plate. The reflectivity of the rough surface (Fig.2-B) was lower than that of the smoothed (Fig.2-A) at the high wave number infr ared region. The reflectivity of the anodized (Fig.2-C) was much lower than that of the rough surfaces and the bands at 1200 and 960 cm-1 were observed in the former. The band inten sities ΔR/R, at 1740, 1450 and 1160 cm-1 of PMMA (Fig.4) were discussed in relation to the abundance of PMMA (Fig.5). Although the linear relationship was obtained for each band of PMMA on the rough surfaces, both the values of ΔR/R and the reproducibility decreased with increase in the R_s values (Table 1). In the case of aluminum with R_s= 0.9, ΔR/R values were found to be less than a half ofΔR/R obtained by a calibration curve based on the molar extinction coefficient of each band (Fig.5). The gradients of the calibration curves from the experiments on the aluminum oxides (AD 30, AD 10) were generally the same as those from the roughened aluminum R_s=0.9 (Table 2). The bands of PMMA were distored when the layer of aluminum oxides got thicker, and the reproducibility of ΔR/R was not good. Photochemical reaction of the 1, 2-naphthoquinone diazides-photosensitized plate was examined by this method. The ratio of the spectral intensities (Fig.7) before and after exposure at 2120, 1720 and 1600 cm-1 gave useful information (Fig.9). The relation between, ΔR/R and the exposure time was obtained using these key bands. The results, indicated that this spectroscopic method was useful to characterization of organic materials on the industrial metal surfaces.

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Infrared emission spectrometry has been developed for the quantitative analysis of organic films on an aluminum plate by the peak ratio method. The following attempts and improvements were made.1) The collector of emission was newly proposed (Fig.1), and the spectrum of quasi black body (Fig.3) was quantitatively investigated. Sample spectra were obtained using the spectrum of quasi black body as reference (Figs.4 and 6).2) Good linear relations were obtained between the emission intensities and the concentration for the 1290, 1125, 1075and 1040 cm-1 bands of a didodecyl phthalate solution (CCl₄) in a 0.1 mm thick KBr liquid cell (Fig.7). The peak intensity (800 cm-1) of poly (methylphenylsiloxane) (PMPS) was measured repeatedly after repainting on an aluminum plate, but the reproducibility was insufficient when peak intensity of only one key band was measured.3) Peak intensity ratio method was critically examined to improve the reproducibility. PMPS in the mixture of PMPS and poly (dimethylsiloxane) on an aluminum plate was quantitatively measured by the peak intensity ratio of the 700 cm-1 and 800 cm-I bands (Fig.8). The relation between the concentration x (%) and intensity ratio (y) was concave which was indicated by the equation.
y=5.01×10^-5x²-5.29×10^-4x+7.34×10^-2
The standard deviation of value y was about 10%, and the reproducibility was about 5%(concentration) at 71.5% of PMPS contents. On the other hand, there was a linear relation between x and y for the concentration of PMPS less than 80%. The standard deviation of this relation was 5% of PMPS contents.

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A half ml of indium solution (100 mg In/m/) followed by 5 ml of buffer solution (8.5 g of Na₂CO₃ and 10.0 g of NaHCO₃ in 200 ml) was added to 500 m l of a water sample in order to form flocculent indium hydroxide precipitates at pH 9-9.5. Trace heavy metals, which are present as suspensions (particle size 1∼10μm. kaolin, bentonite, silica, metal oxides, hydrous metal oxides, calcium carbonate, diatomaceous earth, river sediment, etc. ), complexes with humic acid, and inorganic colloids and ions were simultaneously collected with the precipitates. To the sample solution, 3 ml of mixed anionic surfactant solution (100 mg of sodium oleate and 200 mg of sodium dodecyl sulfate in 300 ml of 70% ethanol) was added. Fine nitrogen bubbles having diameters of. O.5 mm or less were vigorously introduced into the solution to float the precipitates to the solution surface within 30 s. The scum produced on the solution surface was then collected in a scum sampling bottle with the aid of a polyethylene band. The recoveries of trace heavy metals present in various chemical states were greater than 95%. The time required for the entire procedure was about 15 min. The apparatus conveniently used in field work is described (Fig.1).

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A procedure of freeze concentration has been investigated for a dilute aqueous solution of mercury. The sample solution was carefully frozen with stirring in a polyethylene bottle cooled at 15 to 18°C, The concentration of 5 1 of aqueous solutions containing O.020 and 0.040 ppb of mercury was done with the top of the bottle covered with a polyethylene d isk with a center hole. The stirring shaft was fitted through the hole. The results were reproducible and the average recovery was 67%, whereas it was only 32% in the uncovered procedure. The plots of log rc vs. log r, were linear. The initial concentration of the sample can be calculated from the final concentration based on this linear relationship. The errors were within ±15%. In order to prevent the volatile loss of mercury, the concentration was done in the presence of potassium permanganate and sulfuric acid. The concentrated solution was contaminated with mercury in the atmosphere.

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The recommended procedure is as follows. The washed hair sample (0.1, -0.2 g) is digested with concentrated nitric acid and evaporated to nearly dryness. The residue is dissolved in 1 N nitric acid and diluted with water to 20 ml (adjusted to 0.1 to 0.5 N in nitric acid). Twenty μl (iron ≤3 ng, manganese ≤0.3 ng) of the sample solution is introduced into the graphite furnace and the atomic absorption measurements are carried out under the instrumental operating conditions shown in Table 1. The calibration curves obtained when [Fe]/[Mn] = 10(see Fig.1) are used for the simultaneous determination of iron and manganese. This method was applied to 28 hair samples from mental retarded children and the results are given in Fig.2. Mean±: S. D. values 10.8±7.0 ppm for iron, 0.55±0.46 ppm for manganese.

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After 1 g of carbon steel sample was dissolved, iron was removed from the solution by extracting it with isobutyl methyl ketone (MIBK), retaining rare earths in the aqueous phase. The solution was evaporated to dryness and the residue was dissolved in 1.00 ml of (1+10)hydrochloric acid. Forty-microliter aliquots were introduced into the inductively coupled plasma by means of a conventional coaxial glass nebulizer with a spray chamber. Spectral interferences from unknown origin were observed for neodymium and samarium. They could be removed by extracting rare earths with 0.5 mol/l 2-thenoyltrifluoroacetone in benzene after MIBK extraction. The recovery of rare earths at the concentration level of 1, ug/g was more than 80%and their detection limits in the solution were; La: O.01, Ce: O.2, Pr: O.2, Nd: O.2, Sm: 0.2, and Eu: 0.03μg/mi, respectively. Several samples were analyzed and only lanthanum (0.02∼4.15μg/g) was detected.

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A new catalytic method is proposed for the determination of trace amounts of vanadium ( V)In the presence of chlorate, vanadium ( V ) catalyzed the oxidation of p-hydrazinobenzenesulf onic acid to p-sulfobenzenediazonium ion which was then coupled with m-phenylenediamine to form a yellow azo dyestuff (λ_max 454 nm). By measuring the absorbance of the dyestuff at 454 nm, trace amounts of vanadium(V) can be determined. Under the experimental condition s established, a linear working curve was obtained with the effective molar absorptivity of 9.9×10⁵ dml3/mol⋅cm. The reproducibility of the method was satisfactory with c. v. (%) of 2.1, 2.7and 2.0 for four determinations of 0.20, O.60 and 1.00μg of vanadium (V), respectively. It was also, found that higher sensitivity could be obtained by adding tartaric acid as an activator in the reaction system. In this case, the effective molar absorptivity was 1.4×10⁶dm3/mol⋅cm. Positive interferences were observed from more than 5μg of iron (II), iron(III) or selenium (IV). One μg of each copper(II) and molybdenum(IV) also caused a positive interference. Ten μg of aluminum(III) yielded a negative interference.

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An analytical technique using gas chromatographic method has been established for determining minor constituents e. g., He, Ne, H2, Ar and CH4 of residual gas in volcanic gas. A trace amount of Ne and Ar can be determined under the following conditions: MS-5 A, carrier gas He, temp.-50∼0°C, 2°C/min (Procedure A). A trace amount of He and H₂ can be determined under the following conditions: MS-5 A, carrier gas Ar, temp. -50°C (Procedure B). When applied to the analysis of the residual gas in volcanic (fumarolic) gas at Kurinodake region, Kirishima, the following data were obtained: He O.0210%, Ne 0.00034%, Ar O.672%, H₂ 7.40%, N₂ 64.8 0% and CH₄ 27.11%.

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Influence of external light on the sensitivity and accuracy for the measurements of ionselective electrodes (ISEs) was briefly examined for commercial CN-, Cu (II), Cd (II), Pb (II), Cl- and Ag(I) ISEs. In the case of CN- ISEs (solid membrane with a composition of AgI: 80 mol%, Ag₂S: 20 mol%), a slope for log-activity vs. potential curves was increased, for example, to 80 mV upon illumination with visible light (550 W tungsten lamp). As a result of this, apparent sensitivity of the Cl\T- ISE appears practically enhanced. Wavelength and light intensity dependence of the phenomenon was also studied. From these results, a general possibility by light of controlling the reaction responsible for the sensitivity and response time of the ISEs was briefly discussed.
Cu(II) ISEs (CuS: 10 mol%, Ag₂S: 90 m ol%) were also found to be strongly affected by external light. However, the effect of light in this case caused largely the parallel shift of the calibration curve to a lower potential; the parallelism being slightly dependent on the concentration of Cu (II) ions, and did not enhance the sensitivity. For Cd (CdS: 10 mol%, Ag₂S: 90 mol%), Pb (PbS: 10 mol%, Ag₂S: 90 mol%), Cl- (Agel: 10 w t%, AgS: 90wt%), and Ag ( I) (Ag₂S: 100 wt%) ISEs, external light did not influence the calibratio n curves and therefore the accuracy of the measurement even under conditions where the light intensity changes appreciably during the course of a series of experiments.

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Methane produced by alkali decomposition of aluminium carbide in aluminium was adsorbed thoroughly with porous polymer (Chromosorb 105) at -20°C. The same results was obtainable at -70°C. The gas was then desorped into nitrogen carrier by heating the polymer at >90°C within 30 min, and oxidized with copper (II) oxide at 780°C. Carbon dioxide thus produced was absorbed with N, N-dimethylformamide containing 2-aminoethanol (5% by vol. ), and then titrated with the standard solution of 0.001∼0.0005 mol/l tetrabutylammonium hydroxide in benzene containing a small amount of methanol. Carbonate on the surface of aluminium gave serious effect on the amounts of methane produced. Washing with acid on the surface of the sample gave satisfactory results. About 5 ppm of Al₄C₃ in aluminium (2.5μg as C) was determined within the relative standard deviation of 5%. The result corresponded about 0.6 ppm of methane in the nitrogen carrier.

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