Palladium was preliminarily removed by the extractions with thiocyanate-MIBK and with dimethylglyoxime-chloroform.
i) Silver dithizonate was extracted by benzene from the weakly acidic solution and stripped by sodium chloride solution containing a little hydrochloric acid. Silver was extracted again by dithizone-benzene from ammoniacal solution, and the excess dithizone was removed by washing with sodium hydroxide (0.5 N). The absorbance was measured with a 470 mμ filter and a 10 mm cell.
ii) Alternatively silver was extracted by dithizonebenzene from ammoniacal solution containing EDTA, the excess dithizone was removed by sodium hydroxide (0.5 N), and the absorbance was measured. The latter method was applicable when the remained palladium was less than 0.1 mg and only in the absence of gold and mercury.

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A method for the microdetermination of cobalt in nickel and of nickel in cobalt using cathode ray polaro graph, Randles type, is described.
The procedure established is as follows. After dissolving sample, the majority of iron was separated from the solution by extracting it with methyl isobutyl ketone. The resulting solution was adjusted to contain 0.5M NH₄OH +0.1 MNH₄Cl as supporting electrolyte.The current-voltage curves were obtained on the cathode ray screen, and the peak potentials for nickel and cobalt measured in this medium were-1.09 volt and-1.29 volt vs. S.C.E., respectively.
This method was applied to the determination of cobalt and nickel in standard iron samples and unknown metallic cobalt and metallic nickel samples. The results of these analyses agreed well with certificated values and with those obtained by a standardized spectrophotometric method. By using above procedure, the cathode ray polarographic determination of more than 0.01% of nickel in metallic cobalt and more than 0.05% of cobalt in metallic nickel could be made.
The concentration limit of determination of each of cobalt and nickel by this method was 0.03 μg/ml (corresponding to about 5 × 10^-7mol/l).

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Color reaction between tungsten and tiron was studied for a quantitative determination of tungsten. Tungsten reacts with tiron to give a stable complex, which has an absorption maximum at 313 mμ. Beer's law is obeyed over the concentration up to 0.02 mg W per ml. Molar extinction coefficient at 313 mμ is 7.6 × 10³. The complex develops within 30 minutes at pH 5 and is stable for a day, showing 1 : 1 molar ratio of tungsten to tiron. Many ions interfere except for Mg²⁺, Mn²⁺, Co²⁺, As³⁺, Cl^- and SCN^- ions, but they can effectively be separated from tungsten by an anion-exchange in sulfate media.
Most of them can be removed from the ion-exchange column by elution with 0.07 M (NH₄)₂SO₄-0.025 M H₂SO₄ solution, while Mo⁶⁺, Th⁴⁺, Zr⁴⁺ and U⁶⁺ retains strongly on the column.
Tungsten is then recovered by passing 0.5 M NaC1-0.5 M NaOH solution down the column and subjected to the direct determination with tiron.

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The study deals with the spectrophotometric determination of copper with zephiramine that reacts with copper thiocyanate complex to form precipitate extractable in chloroform. The extract is stable enough for at least 3 hours after extraction, and shows an absorption maximum at 440 mμ. The absorbance of the extract is invariable in the acidic region with pH lower than 1.2. The composition of the extracted complex is 1 : 2 in mole ratio of copper to zephiramine. The Beer's law holds for the chloroform extract when copper-thiocyanate-zephiramine was extracted in 10.0 ml chloroform from 25.0 ml sample solution containing 2.0 ×10^-5M (ca. 1.27 ppm)2.0 × 10^-4 M (ca. 12.7 ppm) Cu(II). Most of metal ions do not disturb the determination in their amount equal to that of copper, but small amounts of manganese, bismuth, cobalt and iron interfere.

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Fe²⁺ and Mn³⁺ in Mn-Zn ferrite can be determined by a pair of potentiometric titrations with potassium permanganate after samples are dissolved in strong phosphoric acid (SPA) by the following two methods. Method A: For the determination of Fe²⁺, a sample is dissolved in SPA containing a large amount of oxalic acid by heating the mixture under the controlled conditions. Method B: For the determination of the difference in the amounts of Fe²⁺ and Mn³⁺, a sample is dissolved in SPA in the absence of oxalic acid. Since a small amount of Fe²⁺ in a sample is oxidized in the course of the dissolution, corrections must be added to the titres of potassium permanganate. Two kinds of ferrite were analyzed by the method presented here. The excess or shortage of oxygen in the samples was calculated from the values obtained, and the compositions of the samples were determined.

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Titanometry of antimony pentachloride in ethylene glycol monoethylether (ethyl cellosolve) was investigated. Titanous chloride in ethyl cellosolve has absorption maxima at 265 mμ and 350 mμ which are different from those in its HCl solution. In the potentiometric method, aluminum (99.997%) and stainless steel electrodes gave good results although the titration with conventional metal electrodes was not accurate. Visual titration using Safranine T as an indicator gave a considerable positive error, wheres SbCl₅ soln. colored yellow by the addition of TiCl₃ and discolored by its slight excess. Photometric titration based on this discoloration gave satisfactory results. Reductivities of SbCl₅ in ethyl cellosolve by aluminum electrodes and by stainless steel electrodes were compared.

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3-Hydroxychromone was synthetized via chromanone from phenol and acrylonitrile. It is pale-yellow crystal with m. p. 178.0178.5°C, is insoluble in water but readily soluble in organic solvents. Acid dissociation constant measured by the spectrophotometric method indicated that pK_a=8.3₇. Its reactions with about forty metal ions at various pH were surveyed. Those which reacted but were inextractable into organic solvents were Zn²⁺, Cd²⁺, Hg²⁺, U⁶⁺, and Mn²⁺, while Cu²⁺, Al³⁺, Ga³⁺, In³⁺, Tl³⁺, Sn⁴⁺, Pb²⁺, Zr⁴⁺, Th⁴⁺, Fe³⁺, Co²⁺, Ni²⁺, and Pd²⁺ were extractable. The absorption spectra of the extracted complexes together with the influences of pH on the extraction of the complexes were given.

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Using the dropping mercury electrode, A.C. polarographic behaviors of cadmium, lead and copper oxides in strong phosphoric acid (P₂O₅ 77.6 wt.%) served as the solvent and supporting electrolyte at 130°C have been investigated.
Well-defined A.C. polarograms were obtained for these metal ions in this solvent, and there were satisfactory linear relations between peak heights and ionic concentrations. The peak potentials for cadmium and copper ions were obtained as constant values;-0.85 V and-0.17 V (vs. Pt-coil), but that for lead ion, which shifted to negative side as increasing of the concentration, was from-0.71 V to-0.79 V (vs. Pt coil) in the range of concentrations of 1.3.5.2 m molal. Comparing with individual peak height, it is assumed that these metal ions are present as phosphate-complexes in this solvent and their stabilities are in the following order; Cu>Cd>Pb.

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Studies have been made on fundamental conditions of photometric determination of tantalum by 4-(2-pyridylazo)-resorcin (PAR). Tantalum forms 1:1 chelate with PAR in a buffer solution of Na-citrate and acetic acid to develop orange-red color. The color is the most intense at pH 5.4, and the maximum absorbance is at 545 mμ. The molar extinction coefficient at an hour after the color development is 3.48×10⁴, and Beer's law is obeyed at least to 2 μg Ta/ml. Cobalt(II), titanium(IV), vanadium(V) and iron(III) give positive errors, and cerium(IV) and uranium(VI) give negative errors. The coloration of niobium complex becomes the highest at pH 6.5, but it is yet innegligible in the above condition for tantalum determination and interferes.

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The technique of thin-layer chromatography has been applied to the separation of poly (vinylalcohol) (PVA) from biological materials. A mixture of boric acid and iodine solution was used as the detection reagent. A solvent mixture of propanol-water was, effective in separating on silica gel, and 30% perchloric acid in separating on kieselgur in the presence of starch. The R_f value was unaltered by changes in degree of polymerization (5002, 000). The R_f value of fully hydrolysed PVA was higher than that of partially hydrolysed PVA with 30% perchloric acid on kieselgur.

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A modified method based on JIS and ASTM for continuous determination of tin and antimony in white metal has been planned out. 0.3 to 1 g of sample is decomposed in 20 ml of sulphuric acid and 4 g of potassium sulphate mixture, and 40 ml of hydrochloric acid and 50 ml of water added, and boiled about 5 min. After cooling, the solution is diluted to 250 ml, and antimony is titrated with N/10 potassium permanganate.
Continuously, 10 g of sodium hypophosphite and 5 ml of saturated mercuric chloride solution are added to the previously titrated solution. Then, tin (IV) is reduced to the stannous state by heating in a carbon dioxide atomosphere. After cooling in ice water, tin is titrated with N/10, or N/50 iodine standard solution.
The expelling techniques of sulfur dioxide and arsenic, which interfere with the determination of tin and antimony, were studied in detail.

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A simple automatic titration apparatus was made with a view to avoiding the personal errors which usually accompany volumetric analysis, and for ready titration. A commercial medical syringe was used as the burett. The brass shaft, which had a screw, was rotated by a small, constant speed motor, and the nut on its schaft pushed the inside tube of the syringe. Its calibration curve was a straight line, and passed through the origin.
In order to examine the accuracy of the apparatus, for example, the potential of a glass, or platinum electrode vs., calomel electrode, the specific conductivity, etc., were recorded automatically. and at the same time the volumetric graduations were recorded on the left side of the recording paper with a pen combined with a photoelectric relay. Some examples of titration, i.e., neutralization, redox, and conductometric titrations, etc., were investigated with this apparatus. The results obtained had better accuracy than that of ordinary titration with an indicator. In general, manual conductometric titration is very complicated, but we could easily obtain a titration curve with the new apparatus.

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A rapid and simple procedure for the determination of O, O-dimethyl O-3-methyl-4-nitrophenyl thiophosphate (Sumithion) in some formulations is proposed by utilizing thin-layer chromatographic separation and ultraviolet spectrophotometry.
One ml of a chloroform solution containing 10 mg of sample was applied from a pipette to a 500 μ silica gel plate. After drying, the plate was developed ascendingly with chloroform-methylenedichloride (2+1). Sumithion was separated from 3-methyl-4-nitrophenol, oxo-Sumithion, iso-Sumithion, etc., and was eluted from silica gel with chloroform. Then the amount of Sumithion was determined by measuring the absorbance at 271 mμ.
The method was applied to the determination of Sumithion in emulsifiable formulations, and gave good results.

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A simple infrared spectrophotometric method has been developed for rapid simultaneous determination of Sumithion (O, O-dimethyl O-[3-methyl-4-nitrophenyl] thiophosphate), and Sevin (N-methyl-1-naphthyl carbamate) in dust formulations. Infrared absorptions of chloroform solutions were measured. Key bands used for Sumithion and Sevin were 975 cm^-1 and 1740 cm^-1, and these two components could be determined without interference from each other. The results obtained by analysing standard mixed samples indicated that the method had a good recovery.

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The author has previously given a method of eliminating iron from silica gel of thin-layer chromatographic use with a homogeneous mixture of acetone, hydrochloric acid and methyl iso-butyl ketone. Another method is presented in this paper in which hydrochloric acid and methyl iso-butyl ketone are employed as in the manner of usual liquid-liquid extraction. Silica gel was dipped into 6 M hydrochloric acid in a glass-stoppered centrifugal tube and one-third volume of methyl iso-butyl ketone was put into the vessel. After shaking for 1.5 hrs., the iron attached on the silica gel was dissolved in the acid and transferred into the organic solvent. As much as 23% of total iron contained in the silica gel (estimated as 4×10^-3%) was removed in the organic sofvent by a single extraction and reached 25% after quintuple extractions. The iron attached on the surface of the silica gel was eliminated readily by the above treatment and no interference appeared in chromatographic developement. The amount of the iron released from the silica gel was estimated by photometric method on red iron(III) thiocyanate was in the organic solvent.

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As the spectrophotometric method for the determination of microamounts of gold in pure iron by using Rhodamine B was remarkably interfered with iron, the separation of iron by organic solvent extraction was studied as follows.
One tenth gram of sample is dissolved in aqua regia and the gold is extracted with ethyl ether from hydrochloric acid (1:6) solution. After the ether is removed by heating, the solution is added with 2.5 ml of hydrochloric acid (1:1), 2.5 ml of water, 5 ml of saturated ammonium chloride solution, and 5 ml of Rhodamine B solution (0.04%).
The gold-Rhodamine B complex was extracted with 5 ml of isopropyl ether by shaking for about one minute and the absorbance at 555 mμ is measured against isopropyl ether.
Five folds of Al, As, B, Ca, Ce, Co, Cr, Cu, Mg, Mn, Mo, Nb, Ni, P, Pb, Si, Sn, Ta, Ti, V, W and Zn do not interfere. From 0.1 to 50 ppm of gold in pure iron was determined within about one and a half hours.

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An extraction procedure was introduced in order to eliminate the disturbance of iron in the photometric determination of microamounts of cobalt (010μg) in pure iron using β-nitroso-α-naphthol.
One tenth gram of sample is dissolved in aqua regia, and the iron is extracted with methylisobutylketone from hydrochloric acid (10 : 6) solution. The water layer is separated, and heated to white fumes after adding 5 ml of perchloric acid. Twenty ml of water, 2 ml of citric acid solution (50%), and 3 drops of bromthymolblue alcohol solution (0.1%) are added, and ammonia water is added dropwise unitil the color of the solution becomes green. After 5 ml of β-nitroso-α-naphthol solution (0.04%) is added, the solution is shaken with 5.00 ml of a mixture of ethyl acetate and buthyl acetate (1 : 1) for about one minute. After the lower layer is rejected, the organic layer is washed with 5 ml of hydrochloric acid (1 : 10), and 5 ml of sodium hydroxide solution (4%), alternately, until the aqua layer is no longer colored. Cobalt is determined by measuring the absorbance of the organic layer at 430 mμ against a blank solution.
Ten micrograms of each element of Al, As, B, Ca, Ce, Mg, Nb, P, Pb, Si, Sn, Ta, Ti, W, and Zn do not interfere.

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The sodium borohydride method for the determination of carbonyl groups in dialdehyde starch (DAS) was studied in detail for its application to samples of different sources and properties.
The DAS samples used were made from potato and corn starches, and showed different solution behaviors in the reaction medium.
An alkaline sodium borohydride solution adjusted to pH 9.012.0 with 1% boric acid solution served as the reaction medium. Reactions were carried out at 25°C. The original apparatus was improved for better reproducibility. Dialdehyde contents are calculated from differences between the amount of hydrogen evolved on hydrolysis of sodium borohydride after reaction with carbonyl groups, and that evolved in a blank test. Observed dialdehyde contents varied with reaction pH, but remained constant in the pH range 10.711.5. Within this pH range, and with a reaction time of 2 hrs., the present method gave reproducible results regardless of starch source, and solution behavior of DAS samples. Standard deviations were less than 0.7%.

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Chloroform in pharmaceutical preparations was determined by the extraction method, and gas charomtography.
The sample solution containing 0.020.2 g of chloroform is extracted with 50 ml of toluene containing 0.2 % of n-heptane (internal standard). The chloroform solution obtained is centrifuged, and 1020 μl is injected, at a column temperature of 8090°C, into a gas chromatograph with a Silicone vacuum grease (25%)/Chromosorb P(6080 mesh) column.
The proposed method is more simple, and more rapid, and may be applied to the determination of a microquantity of chloroform when a small volume of solvent is used for extraction.

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[in Japanese]

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[in Japanese]

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