An enrichment procedure for trace amounts of gold in water utilizing the coagulation of soybean protein by adding acids or salts (calcium, magnesium, etc.) and its complex-forming character with heavy metal ions were investigated.
After adding fixed amounts of soybean milk (collector) and δ-gluconic lactone (coagulant) to a sample solution, the mixture was heated to boiling in order to coagulate the protein. The coagulum (soybean curd) was separated from the suspension with a centrifuge and burned to ashes with a low temperature plasma asher. Then the gold collected in it was determined by means of the atomic absorption and emission spectrographic methods. Effects of pH, the amounts of soybean milk added, and the concentration of NaCl in the sample solution on the recovery of gold were examined systematically. The best result was obtained under the following conditions : To a certain amount of sample containing more than 0.01 μg of gold, (2050) ml of 6.34% soybean milk was added and its pH was adjusted to 4.45.0 by adding the suitable amounts of δ-gluconic lactone. This pH range corresponded to the optimum pH for the coagulation of soybean protein. The recovery of gold was 99% or better. NaCl in the sample solution tended to decrease slightly the recovery of gold. The proposed method was applied to the determination of gold at the order of (0.011) ppb in the sample solutions such as water, 3% NaCl water and artificial sea water. This method was also applied to the determination of gold in common salts.

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For the purpose of establishing a conclusive identification method on gas chromatographic analyses of a trace amount of the sulfur compounds in an ambient air, the relative retention times of 33 typical sulfur compounds were measured, as internal standard, diethyl sulfide. The measurements were achieved to compare with the relative retention time of direct injection method into main column (3 mm i. d. 3 m long, phosphoric acid treated glass column) (R_tRd) and that of precolumn injection method throughout cooling precolumn (4 mm i. d. 31 cm long, phosphoric acid treated glass column) (R_tRp) in liquid oxygen. The polarity of the liquid phase of column packings and column temperatures were also examined.
The ratio of relative retention time, R_tRp/R_tRd values of 33 sulfur compounds were 0.71.7 in tris (2-cyanoethoxy) propane (TCEP, strong polarity), 0.72.0 in tricresylphosphate (TCP, poor polarity), 0.52.2 in polyphenylether (PPE, poor polarity), respectively.
In general, the R_tRp/R_tRd values of sulfur compounds even if no effect with increasing of column temperature, but several exceptions were observed, i. e., carbonyl sulfide in TCEP, hydrogen sulfide in TCP, 13 compounds including hydrogen sulfide in PPE..
In conclusion, the estimation of R_tRp values from the R_tRd values are possible qualitatively.

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The kinetics of back extraction have been studied on 2-(2-thiazolylazo)-4-methylphenol (TAC) chelates of zinc(II) and cadmium(II) from chloroform solution into aqueous CyDTA solution. The spectrophotometric determination of Zn(II) and Cd(II) in their mixtures was made simultaneously by the aid of the difference in the rate of hack extraction. TAC chelates of Zn(II) and Cd(II) were extracted at pH 8.210.0 and 8.710.2, respectively. These chelates showed their absorption maximum at 600 nm, and moler absorbances at this wavelength were 3.36 × 10⁴ for Zn(II) chelate and 3.67 × 10⁴ for Cd(II) chelate. The rate of the back extraction of Zn(II) chelate was much lower than that of Cd(II) chelate. The conditional rate constants for Zn(II) and Cd(II) chelates were 1.8 × 10^-3 and 1.6 × 10^-2 s^-1, respectively at pH 9.18, free TAC concentration of 4.8 × 10^-4 M, μ=0.15 and 20°C. The back extraction reactions were of first-order with respect to Zn(II) or Cd(II) chelate and inversely-first order with respect to free TAC and hydrogen ion. The concentration of CyDTA had no effect on the reactions so far as CyDTA was in excess of TAC chelates. Linear extrapolation method was applied to the analysis of the mixtures of Zn(II) and Cd(II) based on the following equation;
(E_o-E_t)=ε_Zn·l·[ZnL₂]k'_Zn·t+ε_Cd·l·[CdL₂]
whereE₀, E_t are the absorbance of the organic phase at reaction time 0 and t, ε_Zn, ε_Cd are the molar absorbances of Zn(II) and Cd(II) chelates of TAC, l is the length of light pass and k'_Zn is the conditional rate constant for Zn(II) chelate. The interferences of Ni(II), Co(II), Cu(II), and Hg(II) were eliminated by preliniinaly extraction with TAC at pH 7.1. Fe (II, III), Mn(II), Cr(III) and Al(III) had no interference.

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Rate-determining parameters in plasma oxidation of high-carbon materials such as graphite, coals and cokes have been elucidated after measuring the rate of weight losses and the surface temperature of the sample during the combustion. The surface temperature was measured by reading oil meniscus moving in a thin capillary thermometer placed on the sample powder employing a cathetometer installed outside of the plasma chamber. Pure graphite underwent the combustion in 0 order reaction with the constant surface temperature, while coals and cokes exhibited decreasing rate of the combustion with time and higher temperatures depending upon their ash contents in spite of slower rates of combustion than in the case of graphite sample.
The experiment suggested a presence of efficient heat evolution at the ashed surface of the sample derived from catalytic recombination of atomic oxygen. Some ash-containing samples gradually raised their surface temperatures during the combustion, whereas the rate of combustion decreased with time. The authors have therefore made a hypothesis that the inward diffusion of atomic oxygen was confined to an effective surface layer for combustion which thickness would be varied with the nature of the given sample. Logarithmic plots of the weight losses of coals and cokes supposing a proper amount of the sample as the effective layer exhibited linear relations with time that meant the 1st order reaction. It appeared also that the side effect of decreasing concentration of atomic oxygen due to the catalytic recombination with increasing ash content in the effective surface layer was roughly counterbalanced with increasing rate coefficient caused by the heat evolution with the recombination.

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A spectrophotometric determination of copper(II) with 2-pyridinealdehyde-2'-hydroxynaphthylimine (PHN) was investigated. The method was based on deep red coloration obtained when copper reacted with PHN. The procedure is as follows:
Transfer 10 ml of the sample solution containing less than 0.2 mg of copper(II) into a 25 ml-volumetric flask, and adjust the pH to 34 by adding 5 ml of acetate buffer solution. Then add 5ml of (0.030.04)% PHN alcoholic solution, and allow to stand for(3060) minutes. After standing, dillute to 25 ml with water, and measure the absorbance of the resulting solution at 482 nm against a reagent blank solution. Under the optimum conditions, the calibration curve was a straight line passing the origin in the range of (0.26.0) mg/l (final concentration) of the solution.
The apparent molar absorption coefficient of the complex at 482 nm was 1.3 × 10⁴ mol^-1 cm². Cobalt(II) interfered with the determination but nickel(II) and iron(III) as much as 5 times of copper(II) did not interfere. The molar ratio of copper(II) to PHN was found to be 1 : 1 by the continuous variation method.

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The extraction of 18 elements with methyl isobutylketone(MIBK) from an aqueous solution of phosphoric acid(3N)-potassium iodide (0.2 M) was examined to find general tendencies toward extraction. Copper, cadmium, lead, silver and bismuth were almost completely extracted, about 95% of arsenic and about 80% of antimony was extracted. Zinc was partially extracted and tin(IV), chromium(VI), manganese(II), iron, molybdenum, aluminum, calcium, magnesium, nickel, cobalt, were not extracted. From the simultaneous extraction of copper, cadmium and lead, 4N phosphoric acid and 0.2 M potassium iodide were used. The proposed method was satisfactorily applied to determination of copper, cadmium and lead in lime stone, fossil shell and zinc die casting. By use of the MIBK extraction the sensitivity was increased to (0.016 μg/ml)/1% for copper, (0.005 μg/ml)/1% for cadmium and (0.06 μ/ml)/1% for lead respectively. When a large amount of copper was determined, wavelength of 2441Å was used beside 3247Å and the sensitivity was (1.6 μg/ml)/1% with MIBK solution. A Hitachi model 207 atomic absorption spectrometer was used.
The recommended procedure is as follows; take (0.51.0) g of sample in a beaker. In the case of lime stone or fossil shell, treat the sample with a small amount of HF and HNO₃ to remove silicon, then, transfer the resulting solution to a beaker. Decompose the sample with HCl and HNO₃ and concentrate the solution until the syrupy solution is resulted. Cool the solution, then add 5 ml of concentrated H₃PO₄ and heat and concentrate the solution until colorless (remove HNO₃ as possible). Cool the solution and transfer it into a separatory funnel with a small amount of water. Add 1 ml of 4 M KI solution, dilute it to 20 ml with water. Shake the solution for (12) min. with 10 ml of MIBK. Separate the organic phase, and determine copper, cadmium and lead with an atomic absorption spectrophotometer against the reagent blank.

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In analysing niobium in low alloy steel with an emission spectrochemical technique using Nb II 3194.977Å as an analytical line, it was found that higher experimental values were obtained in spite of the absence of known interference line. The values of 0.004% to 0.007% were, for example, found in spite of the absence of niobium in the steel samples.
Studying this phenomenon, we found the following facts;
(1) Among the elements such as molybdenum, iron, tungsten, vanadium and titanium which were classified as interfering elements in the JIS G 1253 (1973), the interferences of titanium and molybdenum with larger spectral intensities can be corrected by the formulae,
ΔNb(%)=0.0174Ti(%)-0.0050 (Ti>0.28%)
ΔNb(%)=0.0049Mo(%)-0.0079 (Mo>1.60%)
On the other hand, vanadium do not interfere with niobium, even if vanadium of about 2% is contained in steel samples.
(2) The precision (σ_d) was low for the steel sample containing much manganese.
(3) It was demonstrated by this work that a spectral line of manganese is present at the wavelength position of about 3194.87Å in the vicinity of Nb II 3194.977Å.
(4) The interference of Mn 3194.87Å on the Nb II 3194.977Å can be corrected by the following formula;
ΔNb(%)=0.0034Mn(%)-0.0020 (Mn>0.80%)
By the correction of the interference of the Mn 3194.87Å, the precision (σ_d) of 10 steel samples was much improved and became practically sufficient for the routine analysis.

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Ion-selective electrodes with a liquid membrane or polyvinyl chloride matrix membrane responsive to dl-methylephedrine (MEP) and ephedrine(EP) have been developed.
An organic solvent solution of the tetraphenylborate (TPB) salt of the objective cation was used as the liquid membrane. This organic liquid membrane was poured into the bottom of U-type glass tube or Orion electrode body(Model 92). The electromotive force of the following concentration cell was measured with an Orion pH meter (Model 801) in order to evaluate the electrode membrane performance:
⊕Ag-AgCl or SCE/Reference soln./Liquid membrane/Sample soln./SCE_??_ (Ion-selective electrode)
The PVC(polyvinyl chloride) matrix membrane was prepared by the following procedure; The PVC solution(as 20 w/w% tetrahydrofuran solution), dioctyl phthalate and the TPB salt of the objective cation, were mixed in the weight ratio of 25 : 10 : 2. The mixture was spread on a glass plate and left more than 48 hours in order to evaporate the solvent.
A (510) mm diameter membrane was affixed to aPVC tube (inside diameter: 6 mm, outside diameter: 12 mm) or to an Orion electrode body (Model 92). The following electrochemical cell was assembled to examine the response of the membrane.
⊕Ag-AgCl/Reference soln./PVC membrane/Sample soln./SCE_??_ (Ion-selective electrode)
The MEP ion-selective electrode of the liquid membrane and PVC membrane types exhibited an appropriate Nernstian response to the MEP ion down to 10^-4 M. The EP ion-selective electrode showed a Nernstian response down to 10^-3 M. The membrane potentials of both electrodes were independent of pH from 1.5 to 8.0. The interferences of sodium, potassium, ammonium, and calcium ions were extremely low for the determinations of MEP or EP by the both electrodes. The presence of caffeine, antipyrine, aspirine, aminopyrine, vitamin C, and sulpyrine contained in usual drug caused no disturbance to the membrane potential of the MEP electrode. Diphenhydramine and chlorpheniramine ions interfered greatly. The PVC membrane electrode was useful as an indicator electrode for the precipitation titration of MEP with TPB.

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Trace metals(Cd, Cu, Fe, Mg, Mn, Pb and Zn)in the blood were determined by atomic absorption spectrometry with a flame or flameless system. Protein in the blood was decomposed by means of deep freeze drying, plasma ashing and wet ashing with nitric acid. All metal components in the blood were converted into their nitrates by nitric acid. Each trace element was directly determined by using atomic absorption spectrometer. Interferences by iron, protein and other materials in the blood were corrected with a D₂-lamp. The concentration of trace metals were calculated from the calibration of the trace metals were calculated from the calibration curves by measuring the absorption peak hight of each metal, using an automatic digital concentration read out system. The present method is applicable to the determination of trace metals in a human blood, since the recovery of each trace metal in the blood was (97.6105.2)% and the coefficient of variation of the measured concentration was only (1.27.0)%.

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Previously the authors have made a computer program (named system CHEMICS), which intends to automatically analyse organic compounds consisting of carbon, hydrogen and/or oxygen via spectral information. A problem of this system is that it often builds up more than one structures (called "informational homologues") as analysis result. Two ways of approaching this problem are (1) file retrieval of spectral data and/or (2) more refined analysis of the spectra.
Concerning the second point the authors intended to define a possibility of building up structures via a simulation technique for NMR spectra. The program constructed automatically calculates NMR spectra without the necessity of NMR parameters. The necessary data for input are the structure of the sample and its digitalized spectrum. The calculated results via simulation of built-up structures computed by system CHEMICS are shown. Evidently the simulation technique is effective to reduce the number of the informational homologues.

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A sensitive method for the determination of microamounts of beryllium in aluminum and copper by atomic absorption spectrophotometry using the methylisobutylketone (MIBK) extraction with acetylacetone (AA) was investigated.
An aqueous sample solution containing (0.55) μg of beryllium and less than 100 mg of aluminum or less than 500 mg of copper was taken into a 100-ml separation funnel, and 2 ml of 5% AA, 20 mg of EDTA for 1 mg of aluminum or 8.8 mg of EDTA for 1 mg of copper, and 10 ml of saturated NaClsolution were added. The pH was adjusted to 57 with 10 ml of 2 M NaCH₃COO-CH₃COOH buffer, and the solution was diluted to 50 ml. After 10 minutes, the solution was shaken for 2 minutes with 10 ml of MIBK. The organic phase was introduced into a nitrous oxide-acetylene flame and the absorption measured at 234.9 nm against a reagent blank.
None of metal elements interfered with the determination of beryllium, and beryllium above 0.001% in aluminum, and above 0.0002% in copper was determined. This method was successfully applied to the determination of beryllium in aluminum and copper alloys.

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Potassium ethylxanthate (KEtX) reacts with many metal ions to form chelate compounds which are easily extracted with various kinds of organic solvents. The present paper is concerned with the study of the optimum conditions and the development of sensitive method for the determination of cadmium and copper with atomic absorption spectrophotometry by using solvent extraction in which KEtX is used as a chelating agent. Methylisobutylketone (MIBK) was the best solvent for the extraction of Cd-EtX and Cu-EtX complexes. The general procedure is as follows: into a 50 ml separatory funnel is taken an aliquot of sample solution containing less than 5.0 μg of cadmium or less than 40.0 μg of copper, then 5.0 ml of 10% ammonium acetate solution is added as buffer solution. If necessary, the pH of the solution is adjusted to 8.5 with (1+2) aqueous ammonia or diluted acetic acid. After the addition of 5.0 ml of 5% KEtX solution, the Cd-EtX or Cu-EtX complex is extracted with 10.0 ml of MIBK by shaking for 3 minutes. The MIBK phase is aspirated after the separation from the aqueous phase directly into the flame. With regard to the interference of diverse ions on the solvent extraction, the presence of Co(II), Ni(II), Fe(III), Cr(III) and Al(III) in large excess amounts (above two hundred times as much as cadmium or fifty times as much as copper) affected. By this method, the determination of cadmium and copper in human tissues was performed successfully. Moreover, because the sensitivity and accuracy of the present method were similar to those the method using sodium diethyldithiocarbamate or ammonium pyrollidine dithiocarbamate as a chelating agent, this method may be used satisfactorily for other practical analysis.

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An extraction-photometric method for the determination of cobalt in zirconium and its alloys with 1-nitroso-2-naphthol {T. Sawada and S. Kato, Sumitomo Light Metal Technical Reports, 5, 302 (1964)} was applied to the analysis of nickel- and iron-base alloys which could be used in a high temperature gas cooled reactor.
The amount of 1-nitroso-2-naphthol added must be increased six times as much as the amount used in the original work because nickel and iron consume the reagent. An oxidized product of the reagent which was sometimes obtained during the extraction, could be removed by shaking the extract with an alkaline solution containing hydroxylamine.
The following method (ε=3.5×10⁴) was used for the determination of more than 0.01 % of cobalt in standard samples of high-temperature alloy which are being produced at Japan Atomic Energy Research Institute and for the determination of traces of cobalt in uranium.The method is also useful for analyzing aluminum, molybdenum, tungsten, niobium and titanium.
A nickel-and iron-base alloy(<0.5 g) is dissolved in an acid mixture(HCl : HNO₃ : H₂O=1:1:1). Metaland oxides of uranium (<3g) are dissolved in nitric acid. To a solution (Co<40μg), are added 25ml of 2 M citric acid and 15 ml of 2×10^-2 M 1-nitroso-2-naphthol, and the pH of the solution is adjusted to 3 to 4 with 10 M sodium hydroxide. After addition of 10 ml of conc. hydrochloric acid, the cobalt complex is extracted In exactly 20ml of benzene by shaking vigorously for 1 min. The organic phase is successively washed with 20 ml each of conc. hydrochloric acid, water, 1 M sodium hydroxide and sodium hydroxide (1M)-hydroxylamine hydrochloride (0.5%) by shaking to remove other metals and the excess 1-nitroso-2-naphthol. The absorbance of the organic phase is measured at 410 nm.

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A method for the determination of isomers in methylnaphthalenes by NMR spectroscopy was investigated, and the application of this method to the analysis of imported methylnaphthalenes used as industrial raw materials also examined.
The NMR measurements were made with a HitachiR-20 spectrometer (60 MHz). The probe temperature during measurement was 34°C. In the NMRspectra of 1- and 2-methylnaphthalene and methylbenzoate (internal standard) dissolved in CCl₄, the methyl proton signals appeared at 2.48, 2.30 and 3.83ppm, respectively. The integral intensities of these characteristic peaks were used directly for the determination of the isomers.
The synthetic standard mixtures of two isomers were examined under following conditions: isomer ratio; (1090)% (1.0g of the mixture and 0.5g of methyl benzoate in 1 ml of CCl₄), RF; 4×10 microvolt, Sweep width; 2.4 Hz/s. The standard deviations of 1- and 2-methylnaphthalene were 0.44% and 0.54%. From the results of GC and GC-MS analysis of imported methylnaphthalenes, it was found that the impurities which accompanied with methylnaphthalenes were mainly naphthalene, ethylnaphthalene, biphenyl and indole. The effect of these impurities on the integral intensity measurements could not be observed. This method is rapid and does not require standard methylnaphthalenes.

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This method is based on the conversion of arsenic into arsine followed by microwave excitation in a quartz discharge tube. An aluminum sample {(0.51.0) g} was placed in a reaction vessel, 50 ml of 6 M hydrochloric acid and 0.2 ml of 10% tin(II) chloride solution were added, and the vessel was quickly connected to a liquid nitrogen trap (50 × 0.8 cm o.d., U-shaped glass tubing) via a CaCl₂ tube. Arsine generated was swept by a nitrogen flow of 30 ml/min into the trap. When the sample had been completely dissolved, 2.0 g of granular zinc was added to the vessel and the nitrogen was passed for another 60 min. The trap was then disconnected from the vessel and connected to a discharge tube. Argon was introduced into the trap at a rate of 30 ml/min, and to optimize the discharge conditions, an additional argon flow of 470 ml/min was fed to the discharge through a bypass. When nitrogen had been completely expelled, the discharge was ignited with a Tesla coil. The trap was removed from liquid nitrogen; after 30 s, the arsenic 228.8 nm line appeared, and its peak intensity was measured for the determination. The recovery of arsenic measured with As-76 was about 90%, due to sorption loss on CaCl₂. The lower limit of determination was ca. 0.05 ppm of arsenic in aluminum and the coefficient of variation was 9% at the 0.5 μg level. The time required for a determination was ca. 2 hrs.

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A transparent test sheet for the rapid and semiquantitative determination of small amounts of such metal ions as copper, zinc, cadmium, mercury, manganese and nickel was prepared. The sheet is composed of 1-(2-pyridylazo)-2-naphthol (PAN), tricresyl phosphate (TCP) and polyvinyl chloride (PVC) as color reagent, solvent and supporting material, respectively. The test sheet is colored by immersing in a sample solution. The color intensity of the sheet is proportional to the metal concentration in the sample solution (10^-510^-4M). Generally, 10^-5M of metal ions can be detected.
Preparation of the test sheet: 20 mg of PAN and 1 g of PVC are dissolved in 10 ml of tetrahydrofuran, and the solution is mixed with 1 ml of TCP. The mixture is placed on a glass plate for a few hours to permit slow solvent evaporation. The resulting sheet (0.3 mm thick) is pressed at 90°C under reduced pressure.
Procedure: The sample solution is adjusted to pH 10 with an ammonium chloride-ammonium hydroxide (or glycine-sodium hydroxide) buffer solution and diluted to 10 ml with water. The test sheet is immersed in the solution for 10 min, washed with water, and wiped. The color intensity is compared visually with a standard color series or measured spectrophotometrically.

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