For the determination of copper, iron, lead and zinc as impurity elements in yttrium oxide and yttrium oxide sulfide, the conditions for the extraction of these elements contained at trace amounts with ammonium pyrrolidine dithiocarbamate (APDC)-methyl isobutyl ketone (MIBK) and the atomic absorption spectrometry of them are studied.
The experimental conditions are following: the analytical lines are 3247Å for copper, 2483Å for iron, 2833Å for lead and 2139Å for zinc, and the combustion gas flow rates are 10l/min for air and 0.7l/min for acetylene.
The most suitable pH for the extraction of these metals is 3 to 4. The relationships between the volume ratio(R) of the aqueous solution of each metal ion to MIBK and the extraction ratio are studied in order to concentrate each metal. Copper and lead are extracted over 98% at R=2, and 90% at R=10. Iron and zinc are extracted 85% and 80% at R=2, and 60% and 15% at R=10, respectively. Although the extractions of iron and zinc are not satisfactory at R=2, the reproducibility of extraction of iron is within ±4% and that of zinc is within ±3%, and therefore these extractions are carried out at R=2. The extraction of each metal is not affected by the presence of the large amount of yttrium. The sensitivities of these metals in atomic absorption spectrometry are higher when they are in MIBK than in aqueous solutions. The sensitivity of copper, iron and zinc increases about 7times and that of lead increases 9times when R=2.
A real sample is dissolved in aqua regia, adjusted at pH=3, extracted by APDC-MIBK, and determined by the atomic absorption method. The amounts of these metals as impurity elements in yttrium oxide and yttrium oxide sulfide are found as follows: 2.7 to 3.9ppm for copper, 3.5 to 7.6ppm for iron, 2.5 to 7.5ppm for lead and 2.6 to 7.0 ppm for zinc, and the coefficients of variation are 2.7 to 5.3% for copper, 3.3 to 14.2% for iron, 4.0 to 11.1% for lead and 1.1 to 12.3% for zinc.

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New sampling algorithm of the data acquisition to the digital computer from the gas chromatograph was investigated for minimal number of samplings.
The contribution of the number of samplings (or the length of sampling interval) for a gas chromatographic peak to the errors in chromatographic characteristic values, i. e. peak area, retention time, and peak height, were theoretically and experimentally investigated in previous paper. The peak area was calculated from Simpson's formula, and retention time and peak height were evaluated by quadratic equation, and 13. 4 points of samplings were required for ±4σ peak width. Consequently, Equation (1) was introduced. The relationship mentioned above is validated at any elution time, so the number of samplings is minimized when the sampling interval is increased according to equation (1). In this paper, the sampling algorithm of sampling interval changed according to equation 2 (k=3) was investigated from a practical point of view.
The time of optimum interval changes (t₂, t₃) and reducing rate of number of samplings (N_s/N_c) are discussed for the first component emerged time (t₁) and the final component eluted out time (t₄).
The elution curves of the sample which was mixture of alcohols were sampled by 0.6 sec constant interval, and those obtained 2000 digital data were edited to prepare the data of proper intervals on core memories of digital computer.
The results of data reduction by three different sampling method (programmed for minimal total number of samplings, programmed for minimal number of samplings for each peak and constant sampling interval) are shown in Tables I and II, and those support the validity of the sampling algorithm.

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Although the fluorescent characteristics of many zinc complexes have been investigated, only a few fluorometric methods for the determination of zinc have been reported. We found that zinc (II) reacts with salicyliden-aliphatic amines to form strong fluorescent chelates and some of them are listed in Table I. The present report describes the fluorometric determination of microgram amounts of zinc by using β-salicylidenamino-ethanol (SAE) which gave the strongest fluorescence among the complexing agents tested. SAE was prepared by mixing salicylaldehyde and ethanolamine in a mole ratio of 1:1 in ethyl alcohol and heating under reflux for 1hr. It was purified by distillating twice under reduced pressure, mp 36°C. SAE-Zn chelate has the maxima of the excitation and emission spectra at 375mμ and 440mμ, respectively (Fig. 1). The molar ratio of zinc to SAE in the complex has been comfirmed to be 1:1 by the continuous variation method (Fig. 6). The optimum condition of pH, solvent, reagent concentration and development time were established. The zinc complex showed a constant fluorescence intensity over the pH range of 5.6 to 6.2 (Fig. 2) and in the buffer concentration of 0.1M to 0.3M (Fig. 3). Fig. 4 shows that the zinc complex exhibits the highest fluorescence intensity at 90% DMF. The maximum fluorescence intensity was obtained to be in the reagent concentration range 2×10^-3M4×10^-3M/10ml and the fluorescence produced was stable between 15 and 120min. The recommended procedure was as follows. To 0.5ml of sample solution containing less than 0.1μmol (3.2μg) of zinc, 1.0ml of 3×10^-3M solution of SAE in DMF, 8.0ml of DMF and 0.2M acetate buffer solution of pH 5.6 were added and the whole was made 10.0ml. After 30min, the fluorescence intensity of the solution at 440mμ was measured at an excitation wave length of 375mμ. The calibration curve showed a straight line passing through the origin up to 0.1μ mol of zinc with a standard deviation of ±0.2%. Several ions such as copper, chromium, nickel, iron, tin, aluminum, gallium, beryllium and phosphate gave a serious interference (Table III). Therefore, a prior separation of these interfering ions must be effected.

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Amalgamation method for determination of oxygen in sodium has been examined with special reference to blank values. Although the method is the most widely used for determining oxygen in sodium, several unsolved problems, especially blank correction are encountered in the application of the technique.
Consequently, effects such as atmosphere purity in the glove box for handling sodium, surface area of amalgamation vessel, purification method of mercury, and sampling tube on the blank values were examined. Among these experimental conditions described above, only one condition, for example, surface area of the amalgamation vessel, was varied while keeping the others constant. Oxygen-free amalgam which was prepared by mixing sodium with mercury in the ratio of 1g of sodium to 15ml of mercury and separating the oxide impurities by flotation was used as the sample for blank test. The blank value obtained under the conditions in which one variable was changed was compared with that of standard routine procedure as the reference. If significant difference was found between two blank values, it was considered that the variable contributed to a total blank.
When the inner surface area of amalgamation vessel was varied, the blank value obtained by using a large amalgamation vessel (218cm²), which was used in standard routine procedure, was 8.5±0.9μg of oxygen and 6. 8±1.1μg of oxygen for small one (135cm²). As a result of experiments, which were shown in Table I, it was found that 4.5μg of oxygen was caused by absorbed water on inner surface of the large amalgamation vessel and 2.8μg of oxygen for the small one.
One to three μg of apparent oxygen, which may come from contamination of sodium oxide during the glove box operation, was also observed when the standard procedure was performed by carrying only mercury instead of oxygen-free amalgam through the entire procedure.
On the other hand, Tables II and III showed that argon atmosphere containing no more than 1ppm each of moisture and oxygen did not contribute to blank value, but when oxygen-free amalgam was treated under argon atmosphere containing 7 and 40ppm of moisture and oxygen, respectively, the blank increased threefold.
Effects of purification methods of mercury, i.e., distillation and filtration, and also of drying method of amalgamation vessels on the blank values were not serious as shown in Tables IV and V. Apparent oxygen from stainless steel sampling tube was measured by adding an empty sampling tube into oxygen-free amalgam and was found to be less than 0.5μg of oxygen per 12.7φ×15mm stainless tube which can contain 1g of sodium.
The blank value obtained by intercept method agreed well with that by using oxygen-free amalgam. However, in actual analysis it was advisable to measure the blank value by using oxygen-free amalgam because of possible segregation of oxygen in sodium.

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Although the mixed packing gas chromatography (MPGC) is considered to be essentially equivalent to the mixed liquid gas chromatography (MLGC) if the stationary liquids behave ideally and they are not particularly interactive each other in the chromatographic column with a combination of two liquids of different polarity, some differences had been found in practical applications. To clarify the source of these differences, in this paper, MPGC was compared with MLGC by the examination of the retention ability, the column efficiency, or the tailing reducing effect of them using various combinations of liquids.
Squalane (SQ), di-n-propyl tetrachlorophthalate (DPTCP), dinonyl phthalate (DNP), dibutyl maleate (DBM), tricresyl phosphate (TCP), polyethylene glycol 600 (PEG 600) or 20M (PEG 20M), 1, 2, 3-tris (2-cyanoethoxy) propane (TCEP), or β, β'-oxydipropionitrile (ODPN) was used as a stationary liquid and out of them two miscible liquids were combined as follows: SQ/DPTCP, SQ/DNP, DNP/TCP, TCP/ PEG 600, PEG 600/TCEP, DBM/ODPN, PEG 20M /ODPN, PEG 600/ODPN. The column packing was prepared by mixing two types of packing coated with a single liquid in MPGC, or by coating a uniform mixture of two liquids on the solid support in MLGC.
On comparing the retention data obtained on various columns, it was evident that, in the combinations of low polar liquids such as SQ/DNP or DNP/TCP, there was no remarkable difference of the retention ability between MPGC and MLGC. On the other hand, in the combinations of high polar liquids such as PEG/TCEP or PEG/ODPN, MLGC had a tendency to reduce the specific retention volume of polar solutes. This reduction of retention in MLGC may be based on the fact that the interactions which arised among the liquid molecules interfered with the dissolving or mixing of solute to the mixed liquid. The difference of column efficiency or tailing reducing effect between MPGC and MLGC was not significant. In SQ/DPTCP, where one molecule of DPTCP forms a chargetransfer molecular compound with one molecule of aromatic hydrocarbon, the partition coefficient (K) of the aromatic hydrocarbon on MLGC almost agreed with K on MPGC. Hence, it can be considered that the particular interaction between solute and solvent has not a remarkable effect to differ the retention of solute between MLGC and MPGC. In the same manner as Muhs et al. applied to MLGC, the stability constant of the molecular compound could be determined using K on MPGC.
It is possible to make use of the characteristics of the original liquids sufficiently in MPGC because these liquids may exist independently in the column without a change in quality, but it is not so sometimes in MLGC. Moreover, as MPGC is characterized by the ease of the column preparation and by the possibility of the use of a combination of the liquids immiscible with each other, MPGC may be in superior situation to MLGC for practical usage.

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A new method for the determination of ppb amount of cadmium in sea water was proposed. For the concentration of a trace amount of cadmium in sea water, coprecipitation with strontium carbonate was used as the first step and solvent extraction with sodium diethyldithiocarbamate-methyl-iso-butylketone (DDTC -MIBK) was used as the second step.
Recovery of cadmium was compared by using magnesium, calcium, strontium and barium carbonates as the coprecipitant. Complete recovery of cadmium was obtained from 100ml of solution containing 50μg of cadmium by using 100mg of strontium. For the atomic absorption spectrometry of cadmium, interference was observed in the presence of magnesium or calcium, while it was not in the case of strontium. Optimum amount of 20% ammonium carbonate solution was found to be 5ml for the coprecipitation of 50μg of cadmium from 100ml of solution containing 100mg of strontium. Various washing and dissolving methods of strontium carbonate precipitate were investigated. Three times washing by warm water and dissolving the precipitate with 6N hydrochloric acid after washing down it from the filter paper with a small amount of 0.12N hydrochloric acid, were adopted.
A linear calibration curve was obtained within the concentration range of 10100ppb of cadmium after coprecipitation of it from 2000ml of solution with 2 g of strontium and 100ml of 20% ammonium carbonate solution. After coprecipitation with strontium and solvent extraction with DDTC-MIBK, a sensitive calibration curve was also obtained for 110 ppb of cadmium. A large amount of sodium chloride did not effect on these calibration curves.
In the case of determination of cadmium in sea water, white precipitate was formed when the pH is above 8, after dissolving the strontium carbonate precipitate with hydrochloric acid and neutralizing it by ammonia water. This white precipitate was eliminated by adjusting the pH value at about 7 by using sodium diethylbarbiturate-hydrochloric acid buffer.
Small amounts of cadmium in several synthesized model sea water samples were analysed and a recoveries of about 100% were obtained for 0.58.0ppb of cadmium. Determination of cadmium was performed in sea water samples obtained at several spots of Seto Inland Sea and of Japan Sea. It was found that these samples contained 0.10.8ppb of cadmium. The proposed method was thus confirmed to be useful for the determination of ppb amount of cadmium in sea water.

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A rapid method for concentration, separation and determination of various metal ions using two-step flow-coulometry has been developed. Carbon fiber is used for the working electrode. Carbon fiber, of which diameter is about 10μm, is produced from fur fural and is heat-treated at 1500 to 2000°C. Supporting electrolyte solution (0.5M perchloric acid) is passed through the flow-coulometric column electrode. The working electrode potential of first step (E-I) and second step (E-II) column electrodes are adjusted to sufficiently negative potential (e.g., -1.40V vs. mercurous sulfate electrode, MSE) for electrodeposition of various metal ions (e.g., cadmium, thallium, lead, copper). Some 10^-7 moles of metal ions are injected and electrodeposited near the inlet of E-I. Then, the electrode potential of E-I is changed to a proper and more positive potential to oxidize the most easily oxidizable metal (e.g., -1.180V vs. MSE for cadmium). The metal ion is eluted from E-I and flowed into E-II and electrodeposites there. The quantity of electricity for the electrodeposition at E-II corresponds to the amount of the metal ion. Other metal ions are separated one after another and determined by similar procedures. Micro-amounts (10^-7 moles) of cadmium, lead and copper ions are separated and determined within an error of 5%. Time required for this procedure is less than 3min.
Two kinds of metal ions (e.g., lead and tin in 0.5M perchloric acid) that perform fast redox reactions can be separated when the differesce of redox potentials of these metals is more than 20mV. The possibility is presented regarding the separation of two kinds of metal ions, e.g., copper and bismuth in 0.5M perchloric acid, whose redox potentials are similar but rates of reactions are different considerably. For this purpose, square-wave (±10mV, 1Hz) is super-imposed on the suitable potential near the redox equilibrium.
Micro-amounts (2×10^-7 moles) of cadmium, lead and copper ions have been concentrated and determined from 10l of aqueous solution containing 10^-3 M uranium. The flow-rate of supporting electrolyte is controlled to 10ml/min for concentration and 2ml/min for separation and determination.

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Total contents of allethrin and phthalthrin and their optical isomers were determined on a gas chromatograph (GC) equipped with a hydrogen flame ionization detector. The retention times of the dl-trans isomers of allethrin and phthalthrin were not always equal to the those of the corresponding dl-cis isomers and the difference in the retention times of both isomers were greater on the columns of SE-52 and XE-60 than on LAC-2R-446 and DEGS. So, when the total contents of allethrin and phthalthrin were determined by the peak height, the values were smaller than the actual contents and peak areas had to exactly determined by the use of a digital or analogue integrator. Half-width method and the scissoring and weighing of the peak scrap were not adequate for the peak calculation because the values varied. As phthalthrin was vaporized at higher temperature than allethrin and the stationary phase could not be used at so higher temperature, coated weight of LAC-2R-446 on Chromosorb W for the determination of phthalthrin was 2% although 7% for allethrin. β-Naphthoquinoline and tributoxyethylphosphate were used as internal standards for allethrin and phthalthrin, respectively. Allethrin and phthalthrin could be determined on the column of 5% DEGS by the same procedure.
On the other hand, allethrin and phthalthrin were hydrolyzed to chrysanthemic acid, which was esterified with l-menthol and separated on an optically inactive phase. It has already been reported that diastereoisomeric esters with l-menthol were derived from chrysanthemic acid and separated from one another on the column of QF-1 and that the ratios of d-trans, l-trans and cis (d+l) chrysanthemic acids were determined from their peak area ratios. But, the resolution of the peaks was not complete under the GC condition of the previous paper and peak areas of the samples containing many l-trans and cis isomers were not accurately determined. Neverthless, the resolution of the peak was complete, when the coating of QF-1 increased, the column length was longer and 1 to 3% sodium borate was added to the column support. Preparation of the sample solution for GC was as follows. To allethrin or phthalthrin containing about 30mg as chrysanthemic acid, 1N potassium hydroxide in 70% methanolic solution was added, the mixture was refluxed for 30minutes and acidified with diluted hydrochloric acid after cooled. Chrysanthemic acid produced was extracted with 10ml and 5ml portions of chloroform and chloroform was removedunder reduced pressure after dried over anhydrous sodium sulfate. To the resinous matter, 1ml (20mg) of pyridine, 1ml (84mg) of thionyl chloride, and 1ml (330mg) of l-menthol in toluene solutions were added in this order, the mixture was heated on a boiling water bath for 20minutes and about 0.5μl of the supernatant was injected to GC. GC operating condition for the determination of total contents and isomer ratios were shown in Table I.

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Gallein reacted with iron (III) to form water soluble complex (bluish violet colour) in the presence of excessive cetylpyridinium chloride (CPC) in a weak acidic solution. The complex of gallein-iron (III) CPC was stable and the intensity of the absorbance was enhanced in comparison with gallein-iron (III) complex. The absorption maximum wave length of the complex and the gallein solution were at around 625mμ and 540mμ against distilled water, and the absorbance was constant over the pH range from 3.8to 4.8 adjusted with acetic acid-ammonium acetate buffer solution. The calibration curve at 700mμ was quite linear for 028.0μg/10ml iron (III). The recommended analytical procedure was as follow. To a 10ml volumetric flask was added the sample solution(iron) containing less than 28.0μg of iron (III), 1.5ml of 2.0×10^-2M CPC solution, 3.0ml of acetic acid-ammonium acetate buffer solution (pH4.2) and 1.0ml of 2.0×10^-3M methanolic gallein solution were added to the sample solution (iron). The whole was made up to the mark with distilled water, and the solution was kept at 45°C for 10 minutes. The absorbance of the solution was measured at 700mμ against distilled water. The sensitivity was 0.002μg Fe(III)/cm² for an absorbance of 0.001. Iron-(III) mainly formed 1:1.5 mole ratio complex with an excess gallein at pH 4.2, but they formed in the presence of excessive CPC, a 1:2.0 mole ratio complex which had an absorption maximum at 625mμ where the photometric sensitivity was larger. The mole ratio measurements indicated that the composition of the iron (III)-gallein-CPC complex was 1:2:1. The effect of diverse ions on the absorbance of the complexes was examined and shown. Aluminum(III), indium (III), tin (IV), thorium (IV), zirconium (IV), bismuth (III), antimony (III), oxalic acid, citric acid, tartaric acid, and phosphoric acid must be avoided. Aluminum (III) and mercury (II) could be masked by an addition of sodium fluoride and potassium iodide.

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A simple, rapid and reliable coulometric procedure was presented for the determination of oxygen in titanium by an argon carrier fusion with iron-tin bath, whereby the use of a technique of exchanging crucible filled with a suitable amount and composition of metal bath material in every analysis was effective to get complete gas extraction. Smaller crucibles and a graphite resistance furnace with smaller volume were used for this purpose.
The difference observed in the gas extraction efficiency from the sample when the experiment was made by a continuous analysis and by a single analysis (which is a method of exchanging a crucible in every analysis), was investigated by using a high frequency induction furnace and the resistance furnace, respectively.
In this experiment, the former technique performed a complete gas extraction for the first sample but showed gradual difficulty in the extraction from the next sample, whereas the latter technique always assured complete gas extraction with good reproducibility. The results are shown on Table I.
From the experiment on the sample fusing condition in the furnace, the following results were obtained. When iron only was used as the metal bath, the analytical values were scattered, while both more than 1.5g of iron and 0.7g of tin were added to 0.2g of sample, the precision was improved as shown in Fig. 5. Fig.7 shows the effect of temperature on the gas extraction curve, from which it is found that at least 1900°C is necessary for the complete extraction. The heating time of crucible filled with metal bath should be kept within 10 minutes in order to avoid solidification of bath due to formation of carbide in the graphite crucible.
The analytical results agreed closely with those of vacuum fusion platinum bath method adopted as one of the standard methods. The time for the analysis of one sample was 7 to 10minutes including the exchanging procedure of crucible and degassing of metal bath and the precision was 2 to 4% by the coefficient of variation. The results of the investigation showed that the present coulometric procedure is more suitable for the routine analysis than the vacuum fusion platinum bath method.

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Back-titration with a standard lead solution using XO indicator was investigated to apply for direct determination of lead and titanium in lead titanate and similar compounds.
A total amount of lead and titanium was determined as follows. A known amount of 0.02M EDTA was added to a sample solution and pH value was adjusted to 5.0 with 20% hexamethylenetetramine solution at a temperature below 15°C. The excess amount of the EDTA was titrated with 0.01M standard lead solution. The amount of lead was determined by the similar procedure using ammonium fluoride-boric acid mixture as a masking agent for titanium (IV). Amounts of lead and titanium were determined from two determinations above described.
Ammonium fluoride-boric acid mixture is most suitable as a masking agent for titanium (IV). Boric acid performs to mask the excess of free fluoride ion so that a formation of lead fluoride is prevented. pH adjustment at a temperature below 15°C is recomended to avoide a hydrolysis of titanium (IV). The coefficients of variation (C. V.%) for the analytical results of titanium and lead are 0.37% and 0.23% respectively. Lead titanate (PbTiO₃) and barium lead titanate{(BaPb) TIO₃} were analysed and satisfactory results were obtained.
Procedure: Take exactly about 400mg of the finely ground samples and add 12ml of HCl (3+1). Heat to dissolve and dilute to about 200ml with water. Cool to room temperature and dilute to 250ml exactly. Take 25ml of the solution and 25ml of 0.02M EDTA exactly into two 300ml beakers respectively and dilute to about 100ml with water.
Determination of lead: Add 13ml of ammonium fluoride (10w/v%)-boric acid (4w/v%) mixed solution to one 300ml beaker and mix for 3minutes with a magnetic stirrer. Add one drop of 0.1% o-phenanthroline and ten drops of XO indicator solution. Titrate with 0.01 M standard lead solution to a reddish purple end point (The titre is denoted by A.).
Determination of total amount of lead and titanium: Cool another 300ml beaker containing 100ml of the sample solution in an ice bath to make a temperature of the solution below 15°C and add slowly 16ml of 20% hexamethylenetetramine solution. Remove the ice bath and add a drop of 0.1% o-phenanthroline and 10 drops of XO indicator solution. Titrate with 0.01M standard lead solution to a reddish purple end point (The titre is denoted by B.). The contents of lead and titanium are calculated by following equations.
PbO%=(50-A)×2.232/Sample (mg)×1000
TiO₂%=(A-B)×0.799/Sample (mg)×1000

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The direct potentiometric determination of thiocyanate ion can be carried out with a bromide ion selective electrode. The following parameters of the bromide ion electrode were studied in detail; Nernstain response to thiocyanate ion concentration, the effect of pH on thiocyanate response and the electrode response to other anions. The application of this membrane electrode as an indicator electrode for potentiometric titration was discussed.
The bromide membrane electrode was preconditioned by soaking in 10^-2M potassium thiocyanate solution for over one hour. During the measurement, the test solution was stirred by magnetic-mixer to obtain stable potential valves because of large stirring effect.
The response time for thiocyanate ion was fairly short and reaches equilibrium within ten seconds after the electrode was immersed in the test solution. The potential of the bromide membrane electrode was dependent on the thiocyanate ion concentration to below 10^-6M potassium thiocyanate solutions adjusted to constant ionic strength with potassium nitrate. The response is slightly less than Nernstain and a linear calibration curve is obtained and the value of the slope of potentials vs. logarithmic concentration was approximately 50mV for thiocyanate ion over the concentration range 10^-1 to 10^-5M thiocyanate.
The selectivity was measured in 10^-1₄M solution of the interference, and measured selectivity valves for anions were listed. The electrode does not respond to most common anions such as F^-, NO^-₃, SO₄^2-, CO₃^-, OH^- but responds partly metal complex cyanide ions such as [Fe(CN)₆]^3-, [Fe(CN)₆]^4-. This fact suggests that the bromide membrane electrode responds more unstable complex cyanide ion such as [Cd(CN)₄]^2-, [Zn(CN)₄]^2-, [Cu(CN)₄]^2-.
The interference encountered with S₂O₃^2- is serious. The extremely high selectivity for S₂O₃^2- should result from reduction of the membrane. This electrode was not influenced by pH in the range pH 2.012.0 at 10^-3M thiocyanate ion.
Thiocyanate ion has been titrated potentiometrically with Ag⁺, Hg²⁺ as a reagent and using the bromide selective electrode as an indicator. The well defined reversed S shape of the titration curve could be obtained, and standard deviation of σ=±0.5 on both cases. The potentiometric titration of thiocyanate ion with Ag⁺, Hg²⁺ was also followed by means of the silver metal electrode. The difference between the bromide membrane electrode and silver metalel ectrode was compared.
The bromide electrode responds [Ag(SCN)₂]^-, [Ag(SCN)₃]^2-, [Hg(SCN)₃]^- and [Hg(SCN)₄]^2- formed during the titration, and only one end point observed.
In the case of silver metal electrode, two break point observed in the titration with Hg²⁺.

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The automated chemical structure analysis of organic compounds has attracted much recent interest. We wish to report the identification of lower paraffines by a computer aided-¹³C NMR spectrometry as a link of our automation work. The computation for the identification of paraffines is carried out along the flowdiagram shown in Fig. 1 by feeding the molecular formula and the proton decoupled ¹³C NMR spectrum of a sample paraffine as input. First, all possible isomeric structures are computed based on the molecular formula and the components, CH₃, -CH₂-, -CH and -C- by the structure-building program previously prepared by one of us (Y. K.). Then the chemical shift of each carbon in every isomeric structure is calculated by the aid of parameters shown in Table I. The numerals in Table I assist to compute the deviation of chemical shift of a particular carbon from that of CH₄ (197ppm relative to CS₂) under the consideration of number and type of neighboring alkyl group(s). Finally, a structure whose predicted spectrum is consistent with that of sample within the limit of ±5 ppm is typed out as the most plausible candidate.
The prediction of chemical shifts of 2, 2-dimethylbutane is explained as an example. As shown in p. 917, C₁ of the compound combines with an alkyl group corresponding to the type I, therefore 32 ppm is adopted as a parameter from Table I and thus the chemical shift of C₁ is calculated by subtraction of 32 from 197. Either C₅ or C₆ is also in the same circumstance as well as C₁. The chemical shift of C₂ attached to the types V and VI is calculated by subtraction of (19+14) from 197. C₃ is computed by subtraction of (32+8) from 197 because of the presence of types I and VI. Finally, C₄ with type III is predicted as (197-13). Thus the predicted values are shown as follows (Numerals in parenthesis express the observed chemical shift.): C_{1, 5, 6} 165 (165), C₂ 164 (163), C₃ 157 (157) and C₄ 184 (185).
The above-mentioned computation system has been applied to unknown paraffines A, B, C, and D. By feeding the molecular formula C₅H₁₂ and the spectrum 180, 180, 171, 171, 159 of A to the computer, A was identified with n-pentane. Similarly it was clarified B (C₆H₁₄, 180, 173, 171, 171, 166, 152), C (C₇H₁₆, 175, 175, 166, 166, 166, 160, 155), and D (C₈H₁₈, 180, 180, 171, 171, 164, 164, 161, 161) were identical with 2-methylpentane, 2, 2, 3-trimethylpentane, and n-octane, respectively.

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A rapid and accurate photometric method has been devised for the determination of total-sulfur in igneous rocks. Hydrogen sulfide formed by heating the powdered sample with tin(II)-strong phosphoric acid reagent is determined photometrically by the mercuric thiocyanate method after it is absorbed in a zinc sulfate solution. Tin(II)-strong phosphoric acid reagent is made by heating 78 g of stanous chloride dihydrate under a current of carbon dioxide gas up to 280°C with strong phosphoric acid which is obtained by dehydrating 1000g of phosphoric acid on heating up to 250°C.
Pulverized samples from 0.1 to 0.3g in weight are heated in a current of carbon dioxide gas with 15ml of tin(II)-strong phosphoric acid reagent in a silica test tube at 280°C for 15 minutes. Hydrogen sulfide thus formed is fixed as zinc sulfide in 5ml of 0.3% zinc sulfate solution containing three drops of 1M sodium acetate solution. To separate micro amounts of zinc sulfide, 0.1M sodium hydroxide solution is dropped until the color of zinc sulfate solution is changed to red for phenolphtalein indicator. Then precipitated zinc hydroxide containing zinc sulfide is separated by centrifugal separator and washed by shaking with 10ml of 0.3% sodium carbonate solution and again centrifugalized. Then 0.5ml of 1M acetic acid, 1ml of 0.5% mercuric thiocyanate-methyl alcohol solution and 2ml of 0.7M ferric nitrate-4M perchloric acid solution are added to the precipitate and the whole is mixed. The mixture is diluted to 10ml with redistilled water. The colored solution is shaken vigorously with 0.5ml of carbon tetrachloride in order to remove mercuric sulfide precipitate. After centrifugation, the absorbancy of supernatant solution is measured at the wavelength of 460 mμ against water using 10mm cell.
Results of analysis by this proposed method for the mixed rock samples containing the definite amounts of pyrite, barium sulfate and calcium sulfate showed a good recovery. Application of this method to some rock samples gave results with a coefficient of variation of about 5% for the contents of sulfur 0.010.03%. Total-sulfur in rocks with more than 0.001% can be determined by using about 0.1g of sample within about 30minutes. Total-sulfur contents of two standard rock samples prepared by the U.S. Geological Survey were determined by the proposed method. The data of each sample showed respectively, total-S content of 0.004% for G-1 and 0.012% for W-1.

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A spectrophotometric method for the determination of small amounts of mercury in pure copper has been presented. A small amount of mercury is selectively extracted as mercury-diethyldithiocarbamate complex from an alkaline aqueous solution containing large amounts of copper and EDTA into toluene and is backextracted from the organic layer into a 0.7N nitric acid aqueous solution containing 0.0075M potassium iodide, 0.005M potassium bromate and 0.025M potassium bromide (backextraction solution). Then Crystal Violet colorimetric method is carried out for the determination of mercury in the backextraction solution. The recommended procedure is as follows:
Two grams of sample was gently dissolved in nitric acid (1+1) solution. The pH was ajdusted to 8.09.0 with ammonia after an addition of 40ml of 1M EDTA solution. It was transferred into a separatory funnel, and 5.0ml of 0.1% sodium-diethyldithiocarbamate solution was added. The solution was shaken vigorously with 5ml of toluene for 5min and the aqueous layer was discarded. Ten ml of the backextraction solution was added into the separatory funnel and the mixture was shaken vigorously for 5min and the aqueous layer was transferred into another separatory funnel. Five drops of 20% sodium metabisulphite solution was added in order to reduce the free iodine, then 0.4ml of 1.0% Crystal Violet solution was added and the solution was immediately shaken with 5ml of toluene for 10sec. The amount of mercury was determined from the absorbance of the toluene layer at 605nm within 3min after the extraction.
In case of the presence of copper and EDTA, many elements such as Pb, Zn, Bi, Ni, Co, Sn and Sb are not extracted as DDC complexes into the organic layer. Not more than 0.5mg of silver, 0.1mg of thallium and 5μg of gold do not interfere. Silver at high concentration interferes the first separation by extraction of mercury as DDC complex from the solution containing copper and EDTA. More than 10μg of gold interferes seriously but gold are selectively removed from the toluene layer containing DDC complexes by washing with 0.5N nitric acid solution. In this case, mercury and copper are not removed into the aqueous solution.
The mercury content in some vacuum melt copper and oxygen free highpurity copper was determined to be less than 0.25ppm.

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Photometric and conductimetric determination of chromium(VI) with EDTA and carboxylic acids in N, N-dimethylermamide (DMF) was stuied. Direct determination of chromium (VI) in aqueous solution with EDTA has not been employed because it forms no chelate compound. However, it was found photometrically that chromium (VI) species forms a stable additional compound in DMF.
When an EDTA solution of DMF was added to a sample DMF solution of chromium (VI) and heated up to 6080°C, the color of the solution changed from yellow to violet after few minutes. This violet solution which was assumed to be chromium (VI)EDTA complex, had a maximum absorption at 564 mμ and it was stable. It was found that the molar ratio of chromium (VI) and EDTA in this complex was 1:1 by both a photometric method and a conductimetric method. The molar ratios of chromium(VI) and other carboxylic acids were determined by a photometric and a conductimetric method. The results obtained were as follows; 1:1 and 2:3 in the complex with nitrilo triacetic acid, 1:1 and 1:2 with maleic acid, and 1:1 with maloic acid. The limiting concentration for the determination was found to be about 5ppm.
It was found that a DMF solution of ammonium dichromate, generated ammonium gas and formed precipitate on heating. This precipitate was isolated and analyzcd. The determination of chromium(VI) was made by gravimetry and the qualitative analysis of DMF was made by IR spectrometry. From the results, CrO₃-DMF was proposed for the formula of the precipitate and the reaction was assumed to be written as flows, (NH₄)₂Cr₂O₇+2DMF→2NH₃↑+H₂O+2CrO₃·DMF.
Then the isolation of chromium (VI)-EDTA complex in DMF was investigated. A DMF solution containing chromium (VI) and EDTA in the concentration ratio of 1:1 was prepared and heated up to about 70°C.It was found that a color of the solution changed to violet.After cooling, 5 to 10 times as much as a volume of the sample solution of ether was added to the solution and violet precipitate was obtained. The violet precipitate was filtered under a dry nitrogen stream, washed with ether and dried in vacuum. The composition of the precipitate was estimate to be CrO₃-EDTA by an analysis of chromium (VI) and EDTA by gravimetry and chelatometry.
Since Ag and Tl (I) are precipitated by chromium(VI) in DMF, an indirect determination of Ag and Tl(I) was also investigated. The molar ratio of Ag or Tl(I) and (NH₄)₂Cr₂O₇ in the precipitate was obtained to be 2:1 and it was concluded that they can bedetermined quantitatively.

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A vacuum distillation method is described for the determination of oxygen in sodium. Water absorbed on inner surface of distillation vessel causes high blank values. In order to remove the water, about 1g of sodium in a nickel crucible is distilled prior to the analysis of actual sample. After the empty nickel crucible is removed from the distillation vessel in an inert atmosphere glove box, a stainless steel crucible containing 35g of sodium sample is placed in the vessel and the vessel is taken out of the glove box.
Following the evacuation of the vessel, the crucible is heated at 350°C under vacuum. When the distillation is complete and the vessel has cooled, argon is allowed to enter into the vessel in the glove box, and the crucible is removed through a glass tube to avoid sodium contamination. Residue in the crucible is dissolved in water and titrated with 0.001N sulfuric acid. From the amount of alkali in the residue, the corresponding oxygen can be determined. The results are in good agreement with those obtained by the amalgamation method.

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A small amount of arsenic has been determined colorimetrically by using silver diethyldithiocarbamate in pyridine (Ag-DDTC method). On the other hand, H. Bode reported that a similar reaction also occured in Ag-DDTC chloroform solution by an addition of several solid organic bases such as ephedrine. Recently, S. Nakao et al. obtained a good result by an addition of dimethylformamide.
In this paper, 24 kinds of liquid organic bases were examined. This method based on the fact that AsH₃ reacts with Ag-DDTC in chloroform containing the bases, and the light absorption and the calibration curve of colored products were examined.
The amount of Ag-DDTC and of organic bases in the samples were 1.03×10^-4 mole and 3×10^-2 mole in 10ml of chloroform solution, respectively. However, in the case of triethylamine, 0.26×10^-4 mole of Ag-DDTC in 10ml of chloroform was enough for this purpose. It was concluded from the results that the bases which give an absorption in the visible region to the solution are triethylamine, 2, 4-lutidine, 2, 6-lutidine, α-picoline, β-picoline and γ-picoline. The calibration curves obeyed Beer's law in the concentration range from 1 to 25ppm.
Among these bases, triethylamine gave the best results, namely, in the case of triethylamine, the amount of Ag-DDTC necessary was quarter of other cases. Therefore the authors concluded that triethylamine, which has less offensive smell and is cheaper than pyridine, can be used for the determination of arsenic with Ag-DDTC instead of pyridine.

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A study was made on the sample press technique for laser Raman spectroscopy. Although Raman scattering can of course be observed using a powder sample, a pellet sample can provide Raman spectra with a better S/N ratio. An observation of Raman spectra of L-cystine pellet using back illumination showed that the Raman intensity was scarcely affected by the change in pellet thickness. Therefore, it has become clear that the pellet thickness should be made as small as possible in order to reduce the sample amount. A test was conducted on newly devised pellet making technique which would require the smallest possible sample amount. One method is to put sample powder on potassium bromide powder and to press them into a pellet. Another is to make a pellet out of potassium bromide only, drill a small hole in it, put the sample powder into the hole, and again press the pellet. The sample quantity required by the latter method is 0.51.0 mg. The pellets produced by this method provide Raman spectra with a good S/N ratio.

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It was proposed that a sharp and effective electrophoretic separation of metal ions can be made by applying complex forming agents in a narrow band on the supporting medium (“Cellogel”) moistened uniformly with the background electrolyte (0.1M NaClO₄). As an example, the mixture of ⁹⁰Sr-⁹⁰Y in a radioactive equilibrium was tested by using 0.1M EDTA (pH=3 or 9) as a complexing agent. The Yttrium ion migrating to the cathod reversed its way to the anode after encountering with the front of EDTA band and the radioactive band of yttrium was detected more sharply than the case when no complexing agent was applied. Furthermore, the mobility of Y-EDTA complex was found to be less than that of free EDTA. This method may be applied to separate several metal ions in groups by applying various kinds of complex-forming agents at one time.

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Molecular absorption spectrum of PO was observed for the first time in the flame using the usual type of atomic absorption spectrophotometer and the continuous H₂ lamp as the source, when 1M aqueous solution of H₃PO₄ was aspirated into air-acetylene flame. This absorption spectrum shows γ system of PO near 2300Å, 2380Å, 2460Å and 2500Å, but the absorptions near 2595Å, and α and β systems, which was reported by emission spectrometry, were not observed. As the absorption band near 2460Å gives the largest absorbance of four bands, the line at 2460Å can be used for the determination of phosphorus. The absorption spectrum of PO gives the considerably high background, which may be due to the absorptions of P₂O₅ and other phosphorous compounds. Moreover, the interferences by some cations such as Na, K and Ca were observed, whereas there was no enhancement of absorption by addition of iso-propylalcohol, which was observed in flame emission. Detection limit was 2mg P/ml at 2460Å.

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[in Japanese]

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