Analytical studies on ion-pair partition phenomena of charged metal chelates of our group were reviewed. Ion-pair solvent extraction behavior of 4-(2-pyridylazo) resorcinol-, maleonitrile-2, 3-dithiol-, and some other ligans-metal chelates and their equilibria were studied, and highly selective as well as sensitive spectrophotometric methods for Fe, Co, Ni, Cr, V, Pd, and Pt were developed. A method for estimating the ion-pair extraction constants from the chemical structure of the constituent was also proposed. These ion-pair systems were successfully applied to the ion-pair reversed phase partition high performance liquid chromatograpy (IP-HPLC), in which capacity factors were well correlative with the ion-pair extraction constants. By IP-HPLC, metal ions of sub-ppb level can be determined selectively without any preliminary concentration and separation. Other applications of ion-pair partition phenomena to bubble separation method, ion-selective electrode, ion-pair adsorption film colorimetry, and a new high performance concentration method (ion exchange adsorption-ion-pair desorption method) were also reviewed.

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For accurate determination of selenium in coal, it is essential to decompose samples without loss, to eliminate coexisting metals and inorganic acids, and to correct the background absorption exactly, because selenium is a trace and volatile constituent of coal. In this paper, an accurate technique for determinating selenium in coal is presented based on the atomic absorption spectrometry using a graphite furnace atomizer and Zeeman background corrector. Silicates in the sample are decomposed with HNO₃-HF, and organic materials are digested with HNO₃-HClO₄ until the sample solution turns transparent yellow. And then, selenium is separated by distillation in HCl-HBr solution and determined by atomic absorption spectrometry. An average value of selenium contents in a standard sample of coal, NBS SRM 1632a, was 2.55± 0.29 ppm (R.S.D. =11%, n = 4) that agreed with the reference value, 2.6±0.7 ppm. Two replicate analyses of selenium in some coals, which were fueled at power plant stations in Japan, gave analytical values in the range from 0.3 ppm to 0.5 ppm by the proposed method.

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The emission lines for qualitative analysis of rare earth elements by a simulation technique of ICP spectra were proposed. The spectra were simulated by employing a Gaussian (or a Lorentzian at high concentrations) profile. The simulated spectra corresponded quite well with the observed ones. The emission lines were selected so that the interference was as small as possible. The present qualitative analysis is based on a pattern recognition method whereobserved intensity ratios of the emission lines in each element are compared with those of a single analyte element. The qualitative analysis was performed for twelve standard solutions containing a single rare earth element and for eight standard solutions containing an element other than rare earth elements. The selection of the emission lines and the algorithm of the present qualitative analysis were justified.

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Ion exchange chromatography of Cu(II), Zn(II), Ni(II), Co(II), Fe(II), Mg(II), Mn(II), Cd(II), Pb (II), Ca(II), and Cr(III) were studied by using a conductivity detector. Five kinds of cation exchangers (IV) were prepared newly for the present study. Exchangers IIII are spherical (11±3μm), gel-type, sulfonated stylene-divinylbenzene copolymer (St-DVB), exchange capacities of which are 24, 50, and 85μeq ml^-1, respectively. Exchanger IV is also sulfonated St-DVB (58μm) and has 55μeq ml^-1 capacity. Exchanger V is sulfonated acryl polymer (10±2 μm) and has 47μeg ml^-1 capacity. Among these, exchangers are suitable for the separation of bivalent metal ions. Proper exchange capacity varies according to the concentration and the constitution of the eluent used. As for the eluent, various mixtures of ethylenediamine (ED) and carboxylic acids were investigated. ED-tartrate and ED-citrate systems are superior in general. Retention times of metal ions are shown in Fig. 2 and Fig. 3 for varied pH with the use of exchanger III. A typical chromatogram of 11 kinds of metal ions is shown in Fig. 4, which indicates sufficient separation for the qualitative analysis of the mixtures of bivalent cations. It is not easy at present to deal with Cu, Fe, Cr, and Pb quantitatively.

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Prednisolone (Japanese pharmacopeial grade, 5.0 g) was purified six times from acetone-hexane (1 : 1) mixture (solubility at an ordinary temperature, 3.0 g/l) by the automatic recrystallization method, which had been previously established for the high-purity, high-recovery purification of compounds. It took approximately nine hours on an average to perform each automatic recrystallization by using a 150 W-recrystallization heater at 55 volts. Recoveries were an average of 96% per each recrystallization and 78% after six recrystallizations. The purification of prednisolone was made up to a maximum by four times of the present repeated recrystallizations. The obtained crystals were full of extremely large single crystals, most of which were 0.6 mm to 1.8 mm in length of a longer side. The melting range of this highly purified prednisolone was 234.3240.4°C, which was 4.1°C higher than that of the Japanese Pharmacopeia Prednisolone Reference Standard and 6.6°C higher than that of Japanese pharmacopeial grade one. Significant differences were found in the ultraviolet absorption spectra and the absorption coefficients between the present prednisolone and the Japanese Pharmacopeia Reference Standard. The present prednisolone did not contain any impurity spot in thin-layer chromatograms. The purity of the present prednisolone was evaluated to be above 99.98% by examining the least amount of prednisolone to be practically detectable by thin-layer chromatography. The purity was, furthermore, calculated to be 98.7±0.6 mol% by differential scanning calorimetry and was evaluated accurately to be 99.9% by correcting 1.2% for the decomposition accompanied by melting.

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The phenomenon of anti-Stokes delayed fluorescence (ASDF) is now being exploited to produce analytical techniques of great specificity and selectivity without prior separation. It has the same wavelength as prompt fluorescence of acceptor [A] and originates from the excited singlet state S₁, but a much longer lifetime and a emission wavelength shorter than that of the exciting light. This paper describes the ASDF properties for the mixed system of some aromatic hydrocarbons as acceptor-proflavine and/or eosin as donor [D] in ethanol solution. The spectra of absorption, fluorescence and low temperature phosphorescence (LTP) at 77°K were measured. Singlet and triplet energy levels were deduced from the values of these spectral data. From the experimental results, the following mechanism was proposed to explain ASDF phenomenon : (1): Dhν→¹D*→³D, (2): ³D+A→D+³A, (3): ³A+³A→¹A+A, (4): ³D+³A →D+¹A, (5): ¹A*→A+hν'. The process of triplet-to-singlet energy transfer can occur provided that the triplet level of the acceptor [³A] lies close to [³D≅³A: low transfer efficiency (LTE) type] or below [³D>³A: high transfer efficiency (HTE) type] that of the donor [³D]. In theoretically, if the acceptor triplet lies well above that of the donor, energy transfer to an appreciable extent is impossible [³D<³A: no transfer efficiency (NTE) type]. However, the process of the mixed triplet interaction can give rise to the excited singlet of the acceptor molecules when the sum of the triplet energy is greater than the excited singlet energy of the acceptor. Accordingly, NTE type-mixed system can also shows ASDF emission, although the encounter efficiency and emission efficiency are very low. On the basis of these ASDF properties, the following analytical methods of some aromatic hydrocarbons in ethanol solution were designed. (1): Proflavine [D] (Ex. 465 nm)-perylene (ASDF : 438 nm), phenanthrene (349, 366 nm), anthracene (400 nm) [A] mixed system. (2): Proflavine [D] (Ex. 465 nm)-anthracene (400 nm), phenanthrene (349, 366 nm), triphenylene (354, 364 nm) [A] mixed system. (3): Eosin [D] (Ex. 533 nm)-perylene (438, 466 nm), anthracene (400 nm), triphenylene (354, 364 nm) [A] mixed system. (4): Eosin [D] (Ex. 533 nm)-anthracene (400 nm), phenanthrene (349, 366 nm), naphthalene (324 nm) [A] mixed system. (5): Eosin [D] (Ex. 533 nm)-anthracene (400 nm), triphenylene (354, 372 nm), naphthalene (324 nm) [A] mixed system. By using this method, 10^-710^-8 mol dm^-3 of perylene and anthracene [HTE type] could be determined. In the case of LTE type and/or NTE type mixed system, 10^-610^-7 mol dm^-3 of aromatic hydrocarbons such as naphthalene, phenanthrene, and triphenylene could be determined without interferences from each others.

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Manganese dioxide suspended in aqueous solutions is covered with surface hydroxyl groups formed by hydration. There are two types of surface groups; one acts as an acid (≡MnOH_a) and the other acts as a base (≡MnOH_b). Dissociation of these surface groups (release of H⁺ and OH^- ions) produces negatively charged (≡MnO^-) and positively charged (≡Mn⁺) sites. The difference in the amounts of positive and negative sites is the (net) surface charge, which is counter balanced by electrolyte ions with opposite sign in an electric double layer of the solution phase. This phenomenon is responsible for the ion exchange by manganese dioxide. In this investigation, the amount of surface charge per unit area, or the surface chargedensity, σ, was measured by acid-base titration. σ is zero at a certain pH (pzc), and becorries more positive or more negative as pH decreases or increases from pzc. It was also found that, with increasing concentration of sodium nitrate (ionic strength I), the absolute value of σ increases and pzc shifts slightly to lower pH. An equation was derived for the relationship between σ, pH and I by taking into consideration that 1) the coexisting electrolyte facilitates the acid-base dissociation of the surface by offering counter-cations or anionsto the charged sites, and 2) the dissociation is electrostatically affected by σ. The equation well explains the values of σ measured in wide ranges of pH and I.

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Various kinds of metallic elements are generally contained more or less in plastics. These elements have been practically analyzed in ash obtained by burning plastics. However, this procedure has such problems that metallic elements in question might fly of in the process of burning, and that a large amount of plastics must be burned to obtain an appropriate amount of ash for analysis. We tried to determine metallic elements in polyethylene sheets directly using an electron probe microanalyzer (EPMA). Metal powder or metal oxide powder was mixed with polyethylene powder. Polyethylene sheets were formed from the mixed powder by hot press. Sheet surface was coated with gold, because plastics have poor electro-conductivity. The following experimental conditions were chosen. Coating time: 5 min, sample current:10 nA, and magnification: 100 fold. Zinc, iron, and calcium could be determined reproducibly and accurately in the range from 0.1 to 2.0 wt% by using calibration curves of relative intensity vs. contents.

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A fluorometric method for the determination of micro amounts of gallium with 2-hydroxy-4-methylbenzaldehyde-semicarbazone (HMBS) was established and applied to the analysis of aluminium and aluminium alloy. To a sample solution containing less than 5.0 μg of gallium, were added 0.1% sodium fluoride solution (Ga 05.0μg : 0.05 ml, Ga 01.0μg : 0.02 ml, Ga 00.1μg : 0.01 ml), 2 ml of HMBS solution in DMF (Ga 0 5.0 μg : 0.03%, Ga 00.1μg : 0.01%, Ga 00.1μg : 0.01%), and 0.5 ml of 2 w/v% ammonium acetate solution. The pH of the solution was adjusted to 3.2±0.1 with hydrochloric acid or ammonia solution, and the solution was diluted to 25 ml with water. The fluorescence intensity was measured at 440 nm (λ_ex : 365 nm) against the standard quinine sulfate solution (0.2 μg/ml, 0.02 μg/ml, and 0.01μg/ml). This method was applicable to the determination of gallium above 0.1 ppm in practical samples with satisfactory results, where the gallium was separated from interfering elements by isopropyl ether extraction procedure before the determination.

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2-Nitroso-5-dimethylaminophenol (nitroso-DMAP) reacts with copper(II) ion to form a 1 : 2 complex in an aqueous solution. In the presence of zephiramine (tetradecyldimethylbenzylammonium chloride), a 1 : 3 complex is formed and can be extracted into chloroform. The excess of nitroso-DMAP co-extracted with complex anion into organic phase can be removed by adding an adequate amount of chloride ion at about pH 12. Maximum absorption wavelength of the copper complex in the organic phase is 468 nm, at which the molar absorptivity was found to be 3.6×10⁴ 1 mol^-1 cm^-1. This method was applied to determine micro amounts of copper in iron and steel samples and aluminium alloys. The procedure is as follows. An adequate amount of the sample was dissolved in aqua regia. The resulting solution was evaporated nearly to dryness. The residue was re-dissolved in distilled water to give an adequate volume. Five milliliters of the sample solution were taken into a stoppered test tube. Ascorbic acid and potassium chloride solutions were then added. Dichlorocopper(I) ion was extracted with chloroform solution of zephiramine. The organic phase was shaken with an aqueous solution containing hydrogen peroxide, nitroso-DMAP, potassium chloride, and potassium hydroxide to form the copper complex of nitroso-DMAP and to remove the excess of reagent in the organic phase. The absorbance at 468 nm was measured against the reagent blank.

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Antimony in ambient particulates was digested with HF/HNO₃/H₂SO₄/KMnO₄, and determined by hydride generation atomic absorption spectrometry. The recommended procedure is as follows: 0.050.1 g of particulate sample, 15 ml of nitric acid, 1 ml of sulfuric acid, 10 ml of 46% hydrofluoric acid and 2 ml of 2% potassium permanganate solution were taken in a teflon beaker and heated for 1 h on a hot plate at 250°C. Then the solution was evaporated to nearly dryness. After cooling, the residue was dissolved with 20 ml of 6 M hydrochloric acid, and the solution was diluted to 50 ml with water. Twenty milliliter of this solution (containing less than 0.3 μg of antimony) was transfered to a reaction vessel, then 4 ml of hydrochloric acid, 1 ml of 40% potassium iodate solution and 1 ml of 20% L-ascorbic acid solution were added, and the reaction vessel was attached to a hydride generation apparatus. After the air in the reaction vessel was flushed out with nitrogen stream, 7 ml of 1% sodium borohydride solution was injected. The generated stibine was collected in the vessel for 30 s, and then the generated gas was introduced by nitrogen stream into the quartz cell heated at 1000°C. The proposed method was also applied for the determination of antimony in Urban Particulate Matter of NBS SRM-1648.

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A color reaction of papaverine hydrochloride (Papay. HCl) utilizing a ternary-complex system among Papay., a metal ion, and a halogeno-fluorescein was studied, and fundamental conditions for the spectrophotometric method of Papay. HCl with 2, 4, 5, 7-tetrachlorofluorescein (T. Cl. fl) and palladium(II) {Pd(II)} were discussed. The standard procedure obtained is as follows; Up to 75 μg of Papay. HCl is placed in a 10-ml measuring flask with 0.75 ml of 1.0% polyvinyl alcohol (PVA) solution, 1.0 ml of 1.0x10^-3M Pd(II) solution, 2.5 ml of Walpole buffer solution (sodium acetateacetic acid, pH 5.2) and 1.0 ml of 1.0×10^-3 M T. Cl. fl solution. The solution is diluted to 10 ml with water, kept at 40°C for 15 min and cooled in water for 5 min. Then the absorption difference between the T. Cl. fl-Pd(II)-Papay. and T. Cl. fl-Pd(II) solutions is measured at 540 nm. The apparent molar absorptivity was 4.0×10⁴ dm³ mol^-1 cm^-1. The molar ratio of [Pd(II) : T. Cl. fl : Papav.] in this color reaction was estimated to be 1 : 1 : 1 by continuous variation method and mole ratio methods. The proposed method was applied to the determination of Papav. HCl in pharmaceutical preparations and the analytical results were satisfactory.

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Some decomposition methods were studied for the determination of chlorine in organic and inorganic noble metals compounds. Inorganic compounds could be decomposed by reducing with formic acid in 1% sodium hydroxide solution. This method was carried out in the decomposition flask equipped with refluxcondenser. Organic compounds of palladium could easily be decomposed by sodium alcoholate method (ASTM D 1317), however, organic compounds of rhodium could not. Then, sodium hydroxide fussion method was applied to rhodium compounds. The latter method was as follows. A sample (0.2 g) was taken into a platinum crucible and covered with 10 g of sodium hydroxide. The crucible was heated at 250°C for 30 min and the content was fused over a flame. After cooling, the fused material was dissolved with water, and filtered. Chloride ion in the filtrate was determined by potentiometric titration. The results obtained by these decomposition methods were in good agreement with theoretical values. Relative standard deviations for these methods were less than 0.5%.

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Copper in copper-niobium alloys containing titanium or/and tantalum was spectrophotometrically determined as copper-EDTA complex without prior separation. Procedure : a sample (alloy below 400 mg, containing copper below 120 mg) was dissolved with 10 ml of HNO₃ (30.5%) and 2 ml of HF (46%) in a platinum dish. After the addition of 20 ml of saturated boric acid solution, the solution was put into a beaker containing 1 ml of H₂O₂ (30%), and 10 ml of EDTA (10 w/v%) was then added to the solution. After adjusting the pH to 5.5 with NH₄OH (25%), the solution was diluted to 100 ml with water in a volumetric flask. The absorbance of the final solution was measured at 730 nm against reagent blank.

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A method for the successive determination of cyanide and dicyanoargentate ions in a mixed solution was studied by potentiometric titration using a gold electrode or a silver electrode as the indicator electrode. Cyanide and dicyanoargentate ions could be rapidly titrated with silver nitrate standard solution by using a gold electrode. The mixture of cyanide ion (1×10^-35×10^-3M) and dicyanoargentate ion (1.5×10^-35.5×10^-3 M) were determined with a relative standard deviation less than 0.3%. Nitrate, phosphate, carbonate and sulfate ions did not interfere with the titration. The time needed for a single titration is less than 10 min. The recommended procedure is as follows : Place the alkaline sample solution in a 200 ml beaker. Dilute to about 100 ml with water. Titrate the solution with 0.05 M silver nitrate standard solution.

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