The atomic absorption of silver was remarkably enhanced in the presence of ammonium ion, and the effect was proportional to the concentration of ammonium ion. Application of this enhancing effect to the determination of ammonium ion by atomic absorption was investigated. The enhancing effect was observed only in the atomic absorption of silver, not in Co²⁺, Cu²⁺ and Ni²⁺, although the latter ions form complexes with ammonia in basic medium. The atomic absorption of Ca²⁺ or Mg²⁺ was not affected by the presence of ammonium ion.
The enhancement depended on the pH of the medium, and in the range of pH 8.5 to 10.3 the calibration curve against the ammonium ion concentration was linear up to 20 μg/ml. The slopes of the calibration curves obtained in several concentrations of silver (from 0.32 to 1.28 μg/ml of silver) were parallel. The interference of other metal ions were investigated. No interference was observed in the presence of 4 times of Na⁺ and Cu²⁺, 1.8 times of Ni²⁺, 3.5 times of Co²⁺, 2.5 times of Ba²⁺, and 1.9 times of Cd²⁺ and Sr²⁺ as much as the mass of ammonium ion, respectively. Considerable interferences were observed in the presence of 0.3 times of Ca²⁺ and 0.9 times of Zn²⁺.
The recommended procedure is as follows : ammonium salts are dissolved in water to give the concentration of 17.6, 10.3, and 15.1 μg-NH₃/ml, respectively. To 10 ml of this solution, 10 ml of aqueous solution containing 0.84 mg of NaOH and 12.8 μg of Ag is added, and the mixture is analyzed by atomic absorption spectrophotometry. The typical optimum condition of atomic absorption spectrophotometry were as follows : air pressure, 1.82 kg/cm²; acetylene pressure, 0.6 kg/cm²; air flow rate, 13.2 liter/min; acetylene flow rate, 3.0 liter/min; slit width, 0.18 mm; lamp current, 9 mA; hollow cathode lamp, Ag.
The recovery of the proposed method was 98100%, and the dynamic range was 20 μg/ml of ammonium ion.

View full abstract

The degree of decomposition of industrial inorganic samples containing fluorine was examined by the sodium carbonate and/or by the steam-distillation method and the recommended processes for each sample are presented in Table IV.
The melts after sodium carbonate fusion of the samples under the conditions given in Table I were examined by the X-ray diffraction and chemical analyses. Incompleteness of the fusion found by the two methods agreed well with each other as shown in Table II. Even when the fusion reaction was incomplete, the recovery of fluorine was complete by the subsequent steam-distillation in most cases. The reaction was followed by the differential thermal analysis. The reaction began at 560°C and finished at about 850°C as shown in Fig. 8 and 9. The optimum result was obtained by fusing 0.1 to 0.5 g of the sample with 2 g sodium carbonate for 10 min at 850°C to 860°C. The addition of silica made the subsequent steam-distillation difficult because of separating silica gel. Therefore it is difficult to analyse glass.
Only the steam-distillation gave the complete recovery of fluorine for most samples if suitable mineral acids were used. Fluorite was most readily decomposed whereas aluminum fluoride scarcely decomposed. The readiness was in reverse order of the pyrohydrolysis.
In conclusion Table IV shows the recommended procedure for different samples. The pyrohydrolytic method is ideal when a few samples are analyzed, but is inferior to the above processes when a large number of samples are analyzed.

View full abstract

The complex formation reactions of Chromazurol S (CAS) with aluminum in the presence of various kinds of alkyl quaternary ammonium salts were studied by spectrophotometry and their properties were compared with each other.
The following salts of alkyl quaternary ammonium were used : cetylpyridinium chloride (CPC), a pyridinium type; cetyltrimethylammonium chloride(CTM), a trimethylammonium type; cetyldimethylbenzylammonium chloride (CDMB), a dimethylbenzylammonium type. In addition, polyoxyethylenelaurylamine (POELA) was used as another type of cationic surfactant.
The apparent acid dissociation constants of CAS in the presence of 5.4×10^-4M alkyl quaternary ammonium salts were measured by spectrophotometry. The results obtained were compared with each other. As shown in Table I, in the acid dissociation constants of CAS, the values of k_a3' varied widely with the sorts of alkyl quaternary ammonium salts in comparison with the variation in the values of k_a2' or k_a4'. The values of pk_a3' in the presence of POELA, CPC, CTM, and CDMB were 4.4, 5.0, 5.2 and 5.5 (ionic strength : 0.10, 25°C), respectively.
Aluminum in the presence of each alkyl quaternary ammonium salts formed acidic complexes with CAS in a 1 : 2 molar ratio below pH 5. These complexes showed their absorption maxima at 600 nm, 604 nm, 605 nm and 620 nm in the presence of POELA, CPC, CTM and CDMB, respectively, which were red-shifted with decreasing k_a3'. The equilibrium constants (K₂') of the complex formation reactions between aluminum and CAS in the presence of each alkyl quaternary ammonium salts were measured by spectrophotometry using the equilibrium concentration method as shown in Table II. The values of K₂' in the presence of POELA, CPC, CTM and CDMB were 0.9, 4.0, 3.2 and 2.0 (ionic strength : 0.10, 25°C), respectively, and the value of K₂' increased with increase in K_a3' except the case of POELA.
The molar absorptivities of the complexes at each absorption maximum in the presence of POELA, CPC, CTM and CDMB were 1.18×10⁵, 1.28×10⁵, 1.24×10⁵ and 1.16×10⁵, respectively. The molar absorptivity increased with an increase in the values of K₂'.
In the alkyl quaternary ammonium salts bearing the same type, the values of k_a3' and K₂' increased slightly with decreasing their molecular weights. In that case, no difference in the molar absorptivity of complex was found.
Beer's law was obeyed in the range of 0.0040.15 ppm of aluminum in the presence of each alkyl quaternary ammonium salt. The molar absorptivity of the complex had the maximum value in the presence of CPC, and was 1.28×16⁵.

View full abstract

Some determination methods of formaldehyde at low concentration in ambient air were tested and it was found that the spectrophotometric determination method by T. R. Hauser using 3-methyl-2-benzothiazolone hydrazone was most sensitive and very easy. But in this method the sulfur dioxide that coexists in air gave unneglegible negative interference though the nitrogen dioxide gave no interference. To eliminate the interference by the sulfur dioxide, it was necessary to remove the sulfur dioxide without removing the formaldehyde before bubbling the sample air in absorbing reagent.
Sulfur dioxide is very adsorbent gas, and so it is partially adsorbed on glass fiber filters. We had a thought that, if a glass fiber filter was soaked on aqueous solution of metal salt as CrO₃, MnSO₄, NH₄VO₃, TiCl₃, FeCl₃ and MgSO₄ followed by drying, the sulfur dioxide might be caught more and more on the glass fiber filter by adsorption and oxidation. As a result of our experiments in which we passed the sample air containing a constant concentration of the sulfur dioxide through this filter, it was confirmed that the sulfur dioxide was caught very much on glass fiber filters of both CrO₃ and MnSO₄, and that the formaldehyde was also caught by the CrO₃ filter. Therefore it was concluded that a MnSO₄ filter was most useful for this purpose. This filter was prepared by the following procedure; 10 ml of aqueous solution of MnSO₄ at the concentration of 100 mg/ml was dropped uniformally over 250 cm² glass fiber filter and this filter was dried and cut to small pieces and packed in a glass tube. This filter could thoroughly remove 0.35 ppm sulfur dioxide in air.
The effective life time of this filter was varied remarkably by humidity of sample air. At high relative humidity above 88%, the removal efficiency over 95% was maintained for 3000 minutes for passing 0.35 ppm sulfur dioxide at the flow rate of 1l/min. At low relative humidity 1535%, the efficiency decreased gradually with the passage of sulfur dioxide. In practical ambient air whose concentration of sulfur dioxide was lower than above experiment and whose relative humidity was 2575%, this filter was effective enough on sulfur dioxide removal. If the relative humidity is very low, it is desirable to use a new filter.
It seems that 3-methyl-2-benzothiazolone hydrazone method for the determination of formaldehyde is most sensitive and simple if the sulfur dioxide is removed by this manganese sulfate filter.

View full abstract

A commercial equipment of NO analyzer based on the chemiluminessence method (CLM) was useful for determination of NO in various effluents and polluted air, but was not applicable for measurement of small amounts of sample as in the case of laboratory work.
In this work, the continuous flow system was used for injection of small sample into CLM-NO analyzer. The concentration of NO was measured with Toshiba-Beckman Co. Model 915 CLM NO-NO_x, analyzer, and the response of detector was recorded with TOA Electronics Ltd. electronic polyrecorder Model EPR-6A. This flow system was constructed with the dilution system for introduction of sample into the analyzer and the injection system of sample into the dilution system (Fig. 1). In the dilution system, air which was passed through silicagel column and flowmeter was supplied from an air pump into the analyzer with a constant flow rate (7.5l/min) and pressure (2.8kg/cm², ). Four types of injection method of sample as described below were used.
Method A : A sample which was collected in a gas tight syringe was injected from an injection valve attached to the dilution system. This method was used for sample volume less than 50ml.
Method B : A sample was collected in a gas sampling tube (0.51.0l) through the flowmeter and the needle valve and fed into the dilution system with a constant flow rate.
Method C : For determination of NO generated from various reactions, a reaction tube was connected to the dilution system and the generated NO was purged with carrier gas such as N₂ or air.
Method D : A sample in the pressured tank was lead directly into the dilution system with a constant flow rate. This method was also used for preparation of calibration curve and for calcuration of the dilution factor.
By using these injection methods, the response of the analyzer was measured with standard gasses (89 ppm NO and 10300 ppm NO). Concentration of NO in sample (C₀) was obtained by means of the calculation from the dilution factor according to the equation (1) or the calibration curve.
A linear relationship was obtained between the amount of NO which was injected in the dilution system and the peak area of the response curve in the range of 10 ^-410 mg NO. Reproducibility (relative standard deviation) of these methods were 515% in method A and 0.83.8% in methods B and D.
Method C was applied to the determination of NO generated from NEDA-NO₂^- reaction. Analytical results which were examined by the present method were more exact than those of the colorimetric method, because the present method gave no loss at the sampling procedure. Moreover, the present method enabled us not only to measure rapidly and conveniently, but also to calculate the reaction rate and to observe the condition of the reaction from the response curve.

View full abstract

A set of electrolytic solutions useful in the coulometric generation of Karl Fisher (KF) reagent was proposed. The electrolytic solution consists of a generator solution for anodic electrolyte and a counter solution for cathodic electrolyte. The generator solution was prepared by dissolving KI and SO₂ in pyridine at moderately high concentration. It was found that KI readily dissolved in pyridine which contained an appropriate amount of SO₂ although it was sparingly soluble in pure pyridine. Every 15 ml of the generator solution was sealed hermetically in 25 ml brown ampoule for storage. A portion of one ampoule was usually used for an anodic electrolyte after mixing with about 60 ml of methanol or other alcoholic solvents. Since the generator solution was composed of only KI, SO₂ and pyridine, it was miscible with any solvents suitable for various types of sample.
Several combination of KI and SO₂ in the anodic electrolyte were examined by using the recording coulometric titrator developed by one of the authors with the cell shown in Fig. 1. The concentration of KI in the electrolyte was selected according to the generating current to be used. It was proved that the concentration of KI should be more than 0.03 M for 100% current efficiency of generation of KF reagent at 107.1 mA. The concentration of SO₂ influenced the reaction rate of KF reaction during the titration, and it was decided that at least a final concentration of 0.5 M SO₂ was required to complete the reaction in a reasonable time. On the other hand, too high concentration of SO₂ made the electrolyte unstable against the air oxidation of KI resulting the liberation of I₂, so that a higher concentration than 1.5 M should be avoided. Finally, the pyridine solution contained 0.35M KI and 7 M SO₂ was established as the most suitable composition of generator solution for storage. The generator solution was stable for at least two years.
The counter solution should have a sufficient conductivity to carry the electrolytic current (107.1 mA) and should not contain any substance oxidizing KI or reducing I₂ or producing them. Among several solutions examined, only two solutions were satisfactory. One of them was 0.11 M KI methanolic solution and the other 0.052 M SO₂ in mixed pyridine and methanol solution. Every 25 ml of these solutions was sealed in 25 ml brown ampoule and it was used for the cathodic electrolyte as it was.
One pair of the electrolytic solutions may be used, theoretically, for the titration of about 0.5 g of H₂O in liquid sample and 1.2 g in gaseous or soild samples. The practical limitation will be, however, determined by increase of the volume of the anodic electrolyte and by solubility of liquid and solid samples to be tested.

View full abstract

The titrator was consist of a cell assembly and an instrument which was constructed of an electrolytic current source, a counter circuit with a digital readout, a control circuit of titration and an operation circuit (Fig. 1). Water is determined with the Karl Fischer reagent generated at the anode by electrolysis of exclusive electrolytes.
The electrolytic current source supplies generally a controlled current of 107.1 mA with which 1 μg of water may be titrated by electrolysis for 0.1 second. The counter circuit measures the net time consumed for electrolysis by counting a clock pulse of 100 Hz synchronously by electrolysis. The measured counts are displayed numerically at a unit of 0.1 sec on four “Nixie” tubes, showing 1 μg of water per 1 count.
The controlled current can also be varied within the range of ± 15% by using a three turn potentiometer which serves as a “compensator”. When the compensator dial is set at 10.00, the current is held constant at 107.1 mA, and it may varies the current from 8.50 to 11.50. The stability and reproducibility are within 0.1%. The compensator makes it possible to exhibit figures at a unit of ppm for any weight of sample within 1.000±0.150 g.
Whenever the power switch is turned ON, the instrument is kept a condition at which electrolysis for cancellation of a blank is performed without counting time. The operation switch, SW₂, (Fig. 1) is kept usually at the position of BLANK, by pushing the SW₂ to SAMPLE, relay E is turned ON and the control circuit is suspended the function, and then by pushing the SW₂ to TITN relay E is turned OFF and relay D is turned ON, and titration starts. Even if an operator pushes the SW₂ to TITN prior to pushing to SAMPLE, no change will occour in the operation circuit.
The titration was followed up by detecting the potentials with a pair of polarized platinum electrodes. Signal E_s from the detector is compared with a reference (E_b1=-260 mV or E_b2=-150 mV) in the control circuit(Fig. 3). The value of E_s varies from about -400 mV at an excess of water to about 0 mV at an excess of reagent. From the start of titration (|E_s|>|E_b1|) to the point of |E_s|=|E_b1|, the relay A is turned ON and electrolysis and counting time are advanced. At |E_s|≤|E_b1|, the relay A is turned OFF and electrolysis and counting of time are suspended. Such an operation will be repaeted for a few minutes as the first stage of the control. During |E_b1|>|E_s|>|E_b2|, the reference is changed periodically (by a period of t₁) from E_b1 to E_b2, for a short time (t₂) by action of relay B, and then relay A is turned ON over the same time interval. The periods of t₁and t₂ are set at the timing circuit (Fig. 3). Such an operation will be repeated until |E_s|≤|E_b2| as the second stage of control. After the condition of |E_s|<|E_b2| has been continued over the time of (t₁+t₂+α) where α is a time lag produced by the charge of the capacitor C₁ (Fig. 1), relay D is turned OFF and the titration is completed. Smaller than about 3 mg of water may be determined with the titrator within the precision of 5 μg H₂O.
The titrator may also be permitted to use for the determination of “Bromine Index” by switching the controlled current to 120.75 mA, E_b1 to -550 mV and E_b2 to -280 mV by one touch operation. The “Bromine Index” may be displayed at a unit of 0.01 mg Br₂ per 1 count.

View full abstract

The Andersen sampler was applied to determine the mass frequency distribution of aerosols in urban air. The aerosols were fractionated in eight stages of the Andersen sampler operating at a cubic foot per minute and were collected on stainless steel plates. The size range used was shown in Table I. A membrane filter (Toyo Roshi TM 80; pore size, 0.8 μ) was placed behind the last stage to collect aerosols permeated.
The sampler was operated continuously from 24 to 27 hours, according to the condition of the air pollution or the weather.
Over a wide range of the size, results obtained were not in agreement with those of either the Junge-type distribution or the logarithmic normal distribution. However some part of the results agreed approximately with those of the logarithmic normal distribution.
When the results were represented as a log probability plot as in Fig. 2, and illustrated with a histogram as in Fig. 3, it was easily found that the aerosols comprised a mixture of particles belonging to two populations in which one modal diameter was about 0.40.6 μ, and another was about 35 μ. There was a certain relation between the size distribution of the aerosols in urban air and the concentration of total aerosols (Fig. 4 and 5). The size distribution curve of the range in stages 5, 6 and 7, and the back-up filter were proportional to the concentration of the total aerosols. However, the size distribution curve of the range in stages 0, 1, 2, 3, and 4 were always constant. Therefore it was estimated that the aerosols in urban air consisted of different typical particles which were formed from natural phenomena and artifical works.
The particles with a modal diameter of about 35μ were derived from natural phenomena. On the other hand, the particles about 0.40.6 μ in modal diameter were arised from artifical works. These particles caused an increase in the aerosols concentration in urban air.
The above result was compatible with Lee's data which shows that the mass median diameter (MMD) values of atmospheric sulfate, nitrate, and ammonium particles were about 0.3 to 0.5 μ, and iron, magnesium and phosphate particles were about 3 to 5 μ.

View full abstract

A rate promoted synergistic effect of Capriquat (trioctylmethylammonium chloride) on the extraction of iron(III) with 2-thenoyltrifluoroacetone (TTA=Htta) was studied. The absorption spectrum of the complex of the Fe(III)-TTA-Capriquat system in benzene is very similar to that of Fe(tta)₃, indicating that the mainly extracted species in the presence of Capriquat might be Fe(tta)₃ (Fig. 1). The extraction of iron(III) was remarkably accelerated by the presence of Capriquat and the fact may probably be due to the interaction of TTA of the enol-form with Capriquat (Fig. 2). The formation of the Fe(III)-TTA complex was concluded to occur at the interface between the benzene and aqueous phases. In order to increase the extraction rate synergistically, the concentration of Capriquat should be higher than C.M.C. (Fig. 4).
Since a logarithmic plot of distribution ratio D against the TTA concentration gives a straight line of slope 3, the extraction of iron(III) in the presence of Capriquat may proceed according to the reaction:
Fe³⁺+3Htta, _org=Fe(tta)₃, _org+3H⁺
for which an extraction constant K_ex was estimated to be 10^4.83±0.24 (Fig. 5). The effect of pH on the extraction can be explained quantitatively by using the eq. (3) in the text(Fig. 6).
A recommended procedure for the spectrophotometric determination of iron(III) with a mixture of TTA and Capriquat is proposed as follows:
Transfer the sample solution containing up to 120 μg of iron(III) to a separatory funnel, and adjust the pH to about 1.0 with hydrochloric acid. Then extract with 10 ml of benzene solution containing TTA(0.1 M) and Capriquat (2×10^-3 M) by shaking for 20 min. Add a small amount of anhydrous sodium sulfate to the organic phase and measure the absorbance at 500 nm against water.
The calibration curve obtained by the above-mentioned procedure is linear and passes through the origin, the molar absorptivity being (4640±190) l/ mol·cm. Among diverse ions, large amounts of sulfate, nitrate, vanadium(IV, V), copper(II), molybdenum(VI) and tungsten(VI) interfered with the determination (Table II).

View full abstract

A procedure was proposed for the gas-liquid chromatographic determination of phenylthiocyanate (I) and phenol (II) which were produced by the reaction of benzenediazonium-, thiocyanate- and metal-ions.
The operational conditions were as follows; pretreatment: trimethylsilylation, internal standard: n-dodecane and n-tetradecane, column: stainless steel, φ0.3 cm×2 m, liquid phase: 5% APG-L+1% PEG 6000, supporter: celite 545, 6080 mesh, carrier gas: nitrogen, 30 ml/min, programmed temperature: 4°C/min at 80160°C, detector: FID, measurement: peak height on a chart.
The contents of (I) and (II) were calculated from the experimental equations,
(I):x=y-0.002/0.496; (II):x=y-0.064/1.490
where x was the mass ratio and y was the peak height ratio of a sample to n-dodecane. When the amounts of (I) and (II) were very much different from each other, n-tetradecane was supplied as the secondary standard. In this case, the calculation of content of (I) was performed by the equation, x'=(y'-0.048)/0.568 where x' was the mass ratio and y' was the peak height ratio of (I) to n-tetradecane.
As shown in Table I, (I) and (II) in the model sample solutions were determined with a relative error within 5%.
Then the method was applied to estimation of catalytic effect of some metal ions on the Sandmeyer reaction. After 0.005 mol of aniline had been dissolved in 0.02 mol of sulfuric acid and diazotized with sodium nitrite, sulfamic acid was added to remove an excess of the nitrite. Then magnesium carbonate was added to neutralize the resulting solution. A solution of potassium thiocyanate (0.02 mol) was poured into the diazotized aniline and then 0.005 mol of a metal ion was added with stirring. The reaction products were extracted into diethyl ether after they had stood overnight. n-Dodecane and if necessary, n-tetradecane were added into the extract as an internal standard. Owing to trimethylsilylation of (II) the extract was warmed with 1 ml of hexamethyldisilazane and 0.5 ml of trimethylchlorosilane in the presence of trace pyridine and was analyzed by gas chromatography at the same conditions as described above.
The results were shown in Table II. The catalytic actions of copper(II), copper(I) and iron(II) ions were effective to produce (I), but those of other metal ions such as silver(I), cadmium(II), cobalt(II), chromium (III), iron(III), mercury(II), manganese(II), molybdate, nickel(II), lead(II), tin(II), uranyl, tungstate and zinc(II) ions were weak or negligible. In conclusion, copper(II) ion was the best catalyzer in the reaction, and iron(III) and cobalt(II) ions, which were proposed by Korczynski et al. as an effective catalyzer for (I) were useful to produce (II) rather than (I).

View full abstract

Atomic absorption spectrophotometry of manganese was carried out by using solvent extraction. Potassium ethyl xanthate (KEtX) as a chelating agent reacts with many metal ions to form complexes which are easily extracted with organic solvents. On the solvent extraction of manganese by using ammonium pyrrori-dinedithiocarbamate(APDC) and sodium diethyl-dithiocarbamate (DDTC) as chelating agents, the extracted species in organic solvent are very unstable, but the extracted manganese-EtX complex in MIBK is stable for at least 3 hours.
The general procedure was as follow: Into a 50 ml separatory funnel taken an aliquot of sample solution containing under 10.5 μg of manganese, add 5 ml of 10% ammonium acetate solution as buffer solution. If necessary, adjust the pH of the solution to 7.58.5 with (1+2) ammonia water. After adding 15 ml of 25% KEtX solution, adjust the total volume of aqueous phase to 30 ml with metal free water. Extract the manganese-EtX complex with 10 ml of MIBK by shaking for 3 minutes. Aspirate the MIBK phase after separating the aqueous phase directly into the flame of an atomic absorption spectrophotometer.
The manganese-EtX complex can be extracted quantitatively into MIBK from the aqueous solution of pH 6.59.0. Experimental conditions on the atomic absorption spectrophotometry were as follows: wavelength, 2794.8 Å the current of manganese hollow cathode lamp, 10.0 mÅ; slit width, 10 μm; air flow rate, 7.0 l/min (2.4 kg/cm²); acetylene flow rate, 1.0 l/min (0.15 kg/cm²).
As a result of investigation about interference of diverse ions on the extraction, it was found that the presence of nickel(II), copper(II), silver(I), cadmium(II), aluminum(III) and zinc(II) of forty times as much as manganese and of above 400 μg of ferrocyanide ion affected the determination. The effect of those cations was masked by a pre-extraction with 1% KEtX and MIBK with no effect on the manganese determination. The presence of ferrocyanide ion may cause the formation of manganese ferrocyanide which is not extracted in MIBK.
On the determination of manganese with atomic absorption spectrophotometry by using solvent extraction, this method is superior to the method using APDC with regard to its sensitivity and accuracy. With this method, manganese in human tissues and in formalin after dipping tissues was determined satisfactorily.

View full abstract

For the spectrophotometric determination of nickel, a nickel thiooxine chelate extraction method is presented. The method was subject to a critical test for the analysis of nickel in steels. Chloroform and methyl isobutyl ketone(MIBK) were used as extraction solvents.
Under optimum conditions a linear relationship between the absorbance and the nickel contents of the organic phase was obtained in the range 0 to 100 μg nickel.
Iron, copper and cobalt interfere significantly with the determination. A large amount of the iron was removed by MIBK extraction before the nickel analysis, although a small amount of the iron was back-extracted from an organic phase containing nickel chelate with 2N hydrochloric acid. Copper was masked with sodium thiosulfate, and cobalt was separated by hack-extraction of nickel with dilute hydrochloric acid.
The recommended procedure is as follows: Dissolve 0.25 g of a sample in a mixture of hot nitric acid and perchloric acid or aqua regia. Put the sample solution in a 250 ml volumetric flask. Adjust the concentration of hydrochloric acid in the solution to 6 N after dilution to the volume. Pipet a 10 ml aliquot into a separatory funnel, then add 10 ml of 6 N hydrochloric acid. Extract the iron ions from the resulting solution to 30 ml of MIBK by shaking vigorously. Transfer the aqueous layer to another funnel and wash the organic layer with 10 ml of 6 N hydrochloric acid. Combine all the aqueous phases and shake for 3 min with 20 ml of MIBK again. Discard the organic phase and transfer the aqueous phase to a 100 ml beaker. Evaporate the solution to remove most of the hydrochloric acid. Then add 5 ml of a 5% ascorbic acid solution, dilute to about 50 ml with water and adjust the pH of the solution to 4.0. Add 5 g of sodium thiosulfate to the solution. After complete dissolution of sodium thiosulfate, add 0.6 ml of a methyl alcohol solution of 0.2% thiooxine and extract the nickel chelate with 10 ml of chloroform or MIBK by shaking the funnel for 2 minutes. Measure the absorbance of the chloroform(540 nm) or MIBK layer(550 nm). In the presence of cobalt in the extract, nickel is back-extracted into 30 ml of hydrochloric acid(1 : 1.25), and then the absorbance of the organic solvent is measured again. The nickel content is calculated from the difference in the absorbance.
The proposed method was applied to the determination of nickel in chrome steel. For nickel chromium and stainless steels, more diluted solutions than in the chrome steel were used.
Relative errors were in the range 1 to 5%.

View full abstract

The drain tube which is usually installed at the bottom of an ebulliometer frequently becomes a dead-space. After a solid pellet or crystals are introduced to the ebulliometer, small particles either that initially present or that result from the dissolution of larger ones often enter into this tube and remain undissolved there. If this happens, the concentration of the boiling liquid does not correspond with the weight of sample added, attainment of temperature equilibrium is delayed, and too high values for the molecular weight are obtained.
We have found that this trouble can be avoided by introducing mercury into the drain tube from a rubber bulb {see Fig. 1, (a)} and confirmed that this precaution leads to more accurate results.
We would therefore recommend an improved type of drain cock as illustrated in Fig. 1, (b).

View full abstract

The solvent extraction method is used for separating Cr(III) and Cr(VI), which are determined by means of atomic absorption spectrophotometry. In this paper, the use of high molecular amines-xylene solutions was investigated for extracting Cr(VI). Cr(VI) was extracted with HCl-acidified 1% Amberlite LA-1-xylene solution. After separating the organic phase, Cr(VI) in the phase was determined by atomic absorption spectrophotometry at 3579 Å in air-C₂H₂ flame. The calibration curve is linear for less than 100 μg of Cr(VI). Cr(III), Zn, Cu, Fe(III), Ni, and Mn(II) do not affect the determination in their amount of less than 1000 μg. Pb interferes with it in the amount of 10 μg. The standard deviation of absorbances, which was measured 5 times, was 0.005 with the waste water from plating.

View full abstract

The chemical shifts of methylene carbons in phenol novolac resins by carbon-13 nuclear magnetic resonance (C-13 NMR) and the semi-quantitative analysis of 2, 2'-, 2, 4'- and 4, 4'-methylene linkages were discussed. As standards 2, 2'-, 2, 4'- and 4, 4'-dihydroxydiphenylmethanes(DPM) and homologues of p-cresol novolac resins were used. The experimental parameters were as follows: instrument; JOEL Model MH-100 for proton NMR, Model PS-100 and PFT-100 for C-13 FT-NMR, computer; JEC Model-7E, lock system; internal, reference; tetramethylsilane, pulse repetition; 2 sec, numbers of scan; 20004000, data points; 8192, tube; 8 mm in diameter, solvent; d-pyridine, pulse width; 11 μ sec (45°), temperature; room temperature, sample concentration; about 100 mg/ml.
The C-13 NMR chemical shifts of 2, 2'-, 2, 4'- and 4, 4'-DPM were 30.9, 35.6 and 40.6 ppm, respectively. It seemed that the dependence of C-13 NMR chemical shifts on the molecular weight were small, because the C-13 NMR chemical shifts of methylene carbons of the dimer, trimer and tetramer of p-cresol novolac resins were 30.9, 30.7 and 30.6 and 30.9 ppm, respectively. The C-13 NMR signals of methylene carbons of phenol novolac resins were broad and chemical shifts of 2, 2'-, 2, 4'-, and 4, 4'-methylene carbons were 30.531.9, 34.936.3 and 40.141.4 ppm.
The relative content of 2, 2'-, 2, 4'-, 4, 4'-methylene linkages in phenol novolac both random and high-ortho resins from the relative ratio of each integrated peak area of methylene carbons can be determined semi-quantitatively.

View full abstract

Flotation with iron(III) hydroxide and methyl cellosolve has been proposed for the separation of the low ppb levels of zinc and copper(II) in water. Methyl cellosolve is a new collector to float iron(III) hydroxide, and this method is more rapid and convenient than filtration or centrifugation of the iron(III) hydroxide precipitates, especially those in a large volume of solution. Iron(III), 550 mg, is added to 2001000 ml of water sample, and the pH is adjusted to 8.18.3 to precipitate iron(III) hydroxide. After the addition of 220 ml of methyl cellosolve, the precipitate involving the desired trace element is floated to the surface by bubbling nitrogen into the water through a sintered-glass disc (No. 4). The floated precipitate is transferred and filtered through filter paper(No. 5C) with the aid of a pipet, and then dissolved in 6 M hydrochloric acid. Microgram quantities of zinc and copper(II) can be separated in the yield better than 96% by the proposed method.

View full abstract

[in Japanese]

View full abstract