The reproducibility of the automatic analysis of amino acids is examined by the repeated determinations. i) The ordinate axis of the recorder sheet of the automatic amino acid analyzer such as HITACHI Type KLA-2 should be longer than 25 cm. ii) Small variations in the elution time of each amino acid do not affect the result of determination. iii) The shape of the peak gives a greater effect on the result, and a well-defined Gaussian curve is required to obtain high reproducibility. iv) The absorbance ratios of 440 mμ/570 mμ, and 440 mμ/650 mμ for the reaction products of 52 amino acid components with ninhydrin were determined. The reproducibilities of the estimated ratios are given for 20 standard amino acids.

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The modification of the inert gas fusion-gas chromatographic method, with the purpose for performing trace analysis of oxygen in metals, was investigated.
It has been necessary to reduce the blank value of carbon monoxide for an inert gas fusion method. A small crucible prepared from graphite bar for nuclear application after the treatment for deoxidation by the procedure of silicon penetration at about 2000°C shows an extremely low blank value as 0.080.12 μg oxygen per 3 minutes. The proposed crucible enables the precise determination of oxygen as low concentration as 0.1 μg.

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In order to simplify the field measurement of the auto exhaust gas in urban air, the adsorption method using charcoal was investigated. The recommended method was as follows : 10 l air was passed through the activated charcoal of 0.5 g by means of the suction using a Mariotte bottle, then adsorbed components were desorbed by heating to 350°C and evacuating, and re-trapped. Then n-butane or pentanes as representative pollutants were analyzed by a gas chromatograph, with the values of which the total auto exhaust gas concentration was estimated. One ppb of pollutants was measured using a hydrogen ionization detector. This method was applied to the research of the urban air of Tokyo and was confirmed to be useful for the study of the pollution varing as to time and place.

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In acidimetry of sodium hydroxide solution containing aluminum, colloidal precipitation appears during titration and a complicated potentiometric titration curve is obtained. A rapid method was investigated to titrate such alkali solutions with good accuracy.
(1) It was ascertained that an inflection point corresponding to total sodium hydroxide in the solution always appears on the titration curves of the solutions containing different amount of aluminum. (2) In order to detect the equivalence point of the titration, two stages of differentiation circuits were constructed and a change in the second derivative of the output from a pH indicator electrode was shown on an ammeter. (3) The time interval was measured from the start of titration to the indication of the end point on the ammeter, and the amount of total alkali was obtained from a calibration curve. The titration was finished within one or two minutes, and the determination was made with a relative error less than about 3%.

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A new method for the determination of ultra-micro amount of alkali and alkaline earth metals has been investigated. The method is based on the fact that, when a sample holder (platinum or palladium wire) loaded with one of the salts of above elements is inserted into hydrogen flame, its electric conductivity increases due to the thermal ionization of the elements.
A collector electrode is placed around the flame, an anode is the jet of the flame itself, and the potential difference is impressed between them. Then the electric current through the collector electrode corresponding to the change in the conductivity is measured. The basic diagram and the detector are illustrated in Figs. 1 and 9, respectively.
The electric current is influenced seriously by the flow rate of hydrogen, the applied voltage and the position of the sample holder.
The following experimental conditions were recommended; flow rate of hydrogen: 62 ml/min, potential difference between electrodes: 145 V, and height of the sample holder from jet: 3 mm.
Limits of the detection were; Li 3.2×10^-12 mol, Na 2.4×10^-13 mol, K 1.6×10^-13 mol, Rb 8×10^-14 mol, Cs 8×10^-14 mol, Ca 1.6×10^-11 mol, Sr 1.6×10^-12 mol, and Ba 1.6×10^-12 mol.
The peak areas were plotted against sample sizes for the elements in Figs. 1720. Dynamic ranges over 1:10 were obtained in all cases.

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A method for the spectrophotometric determination of magnesium with Arsenazo I in aluminum-, zinc-, copper-, and nickel-base alloys was presented. The sample was decomposed with either hydrochloric acid, nitric acid, or perchloric acid, and filled up to the volume. To an aliquot containing 10100 μg of magnesium were added 5 ml of 0.1%, Arsenazo I solution and 20 ml of 10% triethanolamine solution, and the pH was adjusted to 10.0 with sodium hydroxide or hydrochloric acid. It was diluted to 100ml and the absorbance at 570 mμ gave the amount of magnesium referred to its calibration curve. One hundred mg of aluminum did not interfere. Interfering chromium was removed as chromyl chloride. Copper, zinc, nickel, etc., were masked with potassium cyanide, and beryllium was masked with sulfosalicylic acid.
The Mg-Arsenazo I complex obeyed Beer's law over the range of 01ppm Mg, and the sensitivity was 0.1 ppm for the final volume.

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A method for the spectrophotometric determination of beryllium with Arsenazo I in aluminum-, magnesium-, and copper-base alloys was presented. The sample was decomposed with either hydrochloric acid or nitric acid, and made up to the volume. After an aliquot containing 550μg of beryllium was neutralized with sodium hydroxide to an adequate pH, 10 ml of 0.1% Arsenazo I solution was added and the pH was adjusted to 12.5 with sodium hydroxide or hydrochloric acid. It was diluted to 100 ml, and the absorbance at 580 mμ gave the amount of beryllium referred to its calibration curve.
The presence of 100 mg of aluminum gave no harm. Magnesium, etc., were masked with EDTA, and copper, etc., were masked with potassium cyanide. 1.00.01% of beryllium in aluminum-, magnesium-, and copper-base alloys was directly determined without separation of the alloying elements. The beryllium-Arsenazo I complex obeyed Beer's law for 00.5ppm of beryllium, and the sensitivity of the determination was 0.05 ppm for the final volume.

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Mixed nitrates of copper, iron, nickel and cobalt was separated on a 0.2 mm thin-layer of silica gel mixed with oxine as a precipitant of metals prepared by the conventional TLC techniques, and their amounts were roughly determined from their band width. The optimum content of oxine in silica gel for each element varied from 2.8 to 14%, in the increasing order for Cu²⁺, Fe³⁺, Ni²⁺ and Co²⁺. Qualitative separation of the four ions were most preferably done with the least dose of oxine.

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The first necessary condition for the smooth development in the precipitation chromatography is that the free osmosis of the developer should not be hindered by the precipitate appeared. The author ascertained that the above condition was fulfilled on a wide range of composition variance of the developer by saturating it with oxine in the development of mixed nitrates of several rare-earth elements on a sheet on oxine-containing filter paper, and investigated on the roles of acid in the developer and organic solvent employed. From the aspects of distribution of La, Ce(III), Pr and Nd on chromatograms were predicted the optimum conditions for the separation of an element from the others and the mutual separation of binary mixture with possible purification of the components. These predictions were ascertained experimentally.

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The higher polarity of free fatty acids often hinders their gas chromatographic determination by their adsorption of the column packings and walls, injection and connection tubes. They also disturb the analysis with their frequent association.
The authors selected the solid support and stationary liquid together with investigation on the silane treatment and the addition of phosphoric acid to avoid the above difficulties, and employed glass beads as the optimum solid support and diethylene glycol adipate polyester as the stationary liquid. They also recommended that every passage of the gas should be constructed with borosilicate glass. By this means, saturated and unsaturated free fatty acids of C₅C₂₂ were separated and determined on reproducible and symmetric peaks under the column temperature below 200°C

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Polonium-210 can easily be obtained by separating it from neutron-irradiated bismuth. A study was made of a suitable method of separating polonium from bismuth by spontaneous deposition. It was found that polonium-210 is quantitatively deposited on a silver plate when 0.1 ml of a 0.11.2 N HNO₃ solution containing polonium and bismuth is contacted with the silver plate for 1 hour or more. If the amount of bismuth is more than 1 gram in 25 ml of polonium solution, the deposition-rate of polonium decreases.

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The near ultraviolet absorption spectra of simple substituted benzenes in a vapor state show fine structure. These A_1g→B_2μ transitions (260 mμ absorption bands) are forbidden, so their absorption strengths are weak. Furthermore, the specificities between their structures, or substituents, and the corresponding spectra were not enough to permit a satisfactory analysis of mixtures. Heterocyclic, and aliphatic compounds showed only incomplete fine structure. It is theoretically considered that all ultraviolet absorption spectra show fine structure, and the exploitation of a useful analytical method is expected as the apparatus is so improved that a fine structure in far ultraviolet region is observed for many kinds of compounds.

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The compositions of dithiophosphate-palladium(II) complexes, which are formed during colorimetric determinations of dithiophosphate insecticides, Dimethoate, and Malathion, have been determined by thin layer chromatography.
The colored solutions, in which the ratio of dithiophosphate concentration to total concentration of palladium ion and dithiophosphate is continuously varied, were applied to a diatomaceous earth plate, and ascendingly developed with benzene-acetone(7:3). Then, the free dithiophosphates were detected using a hydrochloric acid solution of palladium chloride as the chromogenic agent.
Judging from the chlomatogram of the sample, in which no excessice dithiophosphate was detected, the compositions of these colored complexes were determined to be [dithiophosphate] to [Pd]=1:1.

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[in Japanese]

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