Bromide ion was extracted into chloroform as bromo-isoquinoline (iq)-mercury (II) complex (HgBr₂iq₂), which then reacted with dithizone in chloroform to give mercury (II)-dithizonate complex having an absorption maximum at 492 mμ. This reaction was applied to the determination of trace amounts of bromide ion. The extraction ratio of the bromide ion into chloroform from a slightly acidic solution (pH : 5.46.5) was constant and a linear relationship was found between the amount of bromide ion and the absorbance at 498 mμ where the difference in absorbances between the mercury (II) -dithizonate complex and the reagent dithizone was largest. Those ions usually accompanying bromide ion did not interfere with the determination except chloride, iodide, thiocyanate and cyanide, which must have been removed before the determination. Bromide ion in microgram amounts could be determined successfully by the method established.

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The beryllium-, aluminum-, copper- and chromium chelates of 3-methyl, 3-ethyl, 3-n-propyl- and 3-n-butylacetylacetones were synthesized. Thermogravimetric (TGA) measurements indicated that the beryllium- and chromium chelates were thermally stable enough upon application to gas chromatography (GLC), while the copper chelates were unstable and were decomposed prior to vaporization. The aluminum chelates sublimed without decomposition in TGA experiments, but seemed to degradate partly in the elution column of GLC. Micro wax was satisfactory as a stationary liquid. A linear relationship held between the injected amount of the chelate and the corresponding peak area over a considerable range of sample amount, and the GLC method was applicable to the determination of those metal ions.

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During the course of the preparation of highpurity arsenic trichloride, activation analysis of traces of oxygen in arsenic trichloride was carried out using the ¹⁶O (n, p) ¹⁶N ( T_1/2 7.4 sec, mainly 6.13; 7.13 MeV γ ray, 10.4 MeV β ray) reaction with 14 MeV neutrons.
9 g of the sample was sealed in the polyethylene container for irradiation. The permeation of arsenic trichloride through the polyethylene container or the absorption of water was not observed for 24 hours after sealing.
The irradiation time was controlled automatically and the activity of ¹⁶N was measured with a 13/4 in. × 2 in. well-type NaI (Tl) scintillation detector and 800 channel pulse height analyzer. The discriminatory level for the measurement of the radiation from ¹⁶N was determined to be 5.0 MeV by the calibration curve method.
As the primary standard sample, ethyl alcohol was added to anhydrous arsenic trichloride which was prepared by the chlorination of high purity arsenic metal. This standard sample could be useful for few days until the permeation of arsenic trichloride through the polyethylene container would be appreciable.
As the secondary standard sample, 9 g of graphite containing glucose was used after being pressed and molded.
When the matrix is different between the sample, it is necessary to correct the effects of self-shielding against 14 MeV neutrons and self-absorption against radiations (γ + β ray) from ¹⁶N. Especially, when the density of the sample is small, the effect of self-absorption against β ray becomes serious. The attenuation of β-particles depends on the density of the sample. The apparent density of the secondary standard sample was about 2.1, on the other hand the density of arsenic trichloride was 2.16. In this case, the results from both the primary and the secondary standard sample agreed each other, giving a same straight line, and the corrections for such effects were not necessary.
The precision expressed in terms of the coefficient of variation was 612% at the range of 160 mg oxygen, and the determination limit was 60 ppm.
This method was applied to evaluate the total oxygen content in arsenic trichloride in equilibrium with water and hydrochloric acid and also in arsenic trichloride dehydrated by various procedures after equilibrated with water. The results were compared with the water contents in arsenic trichloride obtained by the radiotracer method using tritium as tracer.
These results indicated that, besides containing as the form of H₂O, arsenic trichloride contained large amount of oxygen as other form. Most of oxygen contained as the form of H₂O could be removed by the dehydration with anhydrous magnesium sulfate. Other oxygen, probably existed as the form of AsO⁺, could be removed by the distillation, and it remained in the residue.

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The effect of sample amount and column temperature on the shape of chromatographic peak and the retention time was investigated experimentally by means of a derivative method.
As well known, Cruickshank and Everett proposed to express the peak distortion by skew ratio, R, shown by eqn. (1) and Fig. 1. The skew ratio can simply be measured in the derivative method as the ratio of the derivative peak heights, as given by eqn. (2). In the present work, the peak distortion was discussed in terms of the degree of asymmetry, S, defined as the logarithm of skew ratio.
A close correlation between the shift of retention time and the distortion of peak shape was observed, especially when the column temperature was too high or too low, and this tendency became more remarkable with increasing amount of sample injected.
As shown in Fig. 3, when the column temperature is lower than the optimum one, with increasing sample amount the peak shows a leading shape more prominently and the retention time becomes longer. On the contrary, when the temperature is higher, a more remarkable tailling of the peak is observed and the retention time becomes shorter. The experimental conditions and the data obtained are given in Figs 5 9.
As tabulated in Table II, it was confirmed experimentally with several samples that there is a temperature T₁, at which the degree of asymmetry S does not depend on the amount of sample injected. At this optimum temperature, the degree of asymmetry shows a value S° that lies very closely to zero. Further, a temperature T₂, at which the retention time shows a constant value independent of the sample amount injected was measured. Two optimum temperatures T₁ and T₂ were found to be almost identical in the range of experimental error.
It can be judged simply and rapidly whether the column temperature is suitable or not from these results. For a given sample component under a certain column packing condition, if S°, i. e. the least value of degree of asymmetry, is known, one can easily find whether the temperature is higher or lower than the optimum one, from the measurement of S under the given temperature, as tabulated in Table III. If S° has not been evaluated, by comparing two values of S, namely, S_A obtained for A-μl sample and S_B for B-μl sample, respectively, one can know the suitability of the column temperature.
Most simply, if the absolute value of S be nearly zero, one may judge that the column temperature is not far from the optimum. Thus, it could be said that by an aid of the derivatives gas chromatographic method one can easily obtain an important information concerning the column temperature. An example with a three-component mixture is reproduced in Fig. 10.

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Separation of aluminum by cation exchange resin with 90% tetrahydrofuran (THF) -10% 6N hydrochloric acid as an eluate was applied to the photometric determination of traces of aluminum in iron and steel. This method was also applied to zinc sample. It would be applied to cadmium sample and especially appropriate for concentration of trace aluminum in pure iron.
Less than 5 g of sample was dissolved with 75 ml or smaller volume of hydrochloric acid by heating. 30% hydrogen peroxide was added to oxidize iron. The solution was evaporated to 6N hydrochloric acid solution. THF was added to make 90% THF-10% 6N hydrochloric acid solution (1 g Fe/80 ml). The solution was introduced onto a resin column (Dowex 50, 100 mesh, 1 cmφ × 5 cm). The column was eluted with 50 ml of the eluate. Nickel which interferes the photometric determination of aluminum was first eluted with 150 ml of 0.7N hydrochloric acid. Then aluminum was eluted with 35 ml of 6N hydrochloric acid. The effluent was added with 1 ml of 3N sulfuric acid and heated until it fumes. 2 ml of ascorbic acid (1%) and 2 ml of ο-phenanthroline (1%) were added to mask microamounts of iron adsorbed on the resin. 3 ml of oxine solution (1%) and 2.5 ml of 4F ammonium acetate were added. The solution was transfered into separatory funnel (100 ml) and aluminum-oxine complex was extracted with 10 ml of chloroform. The absorbance was measured at 390 mμ, while chloroform was used as reference solution. A blank experiment was run through the entire procedure.
In the case of 1 g of sample containing 10 μg of aluminum, the permissible limits of copper, vanadium (V), nickel and chromium were 3, 1, 3 and 3 mg, respectively.
The amount of iron which was adsorbed on the resin was 16 μg for 1 g sample and 2535 μg for 5 g sample. The permissible limit of iron for photometric determination was 100 μg.
The reproducibility of this method was examined and the coefficient of variation was 1.4%.
B. S. C. 271 and B. C. S. 275 were analysed and the satisfactory results were obtained.

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Direct fluorometric determination of total glucuronic acid in the presence of sugars is described. The method is based on a reaction of glucuronolactone (GL) with hydrazine and zirconyl chloride which results an emission of blue fluorescence at 457 mμ by an excitation at 382 m. GL and glucuronic acid (GA) are usually in an equilibrium in aqueous solutions and GA also emits a fluorescence at the same wavelength by the same excitation by the same reaction but the intensity of the fluorescence due to GA is one half of that of GL. In the method, GA is converted to GL prior to the determination by heating with acetic and the solution is then diluted with water in order to make the concentration of the acetic acid left in the solution below 0.75% v/v. The sample solution is added 10% v/v of citric acidcitrate buffer at pH 5 and the use of this buffer is important because it increases the intensity of the fluorescence more than any other buffers studied. The analytical procedure is as follows.
Transfer a 1 ml portion of the test solution containing 1 to 80 μg of GL and 10% v/v of the citric acid buffer into a 20 ml of volumetric flask. Add 1 ml of 2% hydrazine sulfate in 16.5% sodium acetate (3H₂O) and heat in a water bath at 70°C for 30 min and cool to room temperature. Add 15 ml of acetic acid and 1 ml of 6% zirconyl chloride, heat again at 70°C for one hour, cool to room temperature and then adjust the volume by water. Measure the fluorescence at the wavelength described above.
The fluorescence was stable at least more than 10 hours at room temperature and a linear relationship was observed up to 4 μg/ml of GL in the final solution. The present method is highly specific and practically no interference is caused by sugars such as glucose, saccharose and lactose which are commonly contained in pharmaceuticals unless the sum of their amounts exceeds approximately 15 times of GL. This method has been applied to direct analysis of total GA in pharmaceuticals and the above procedure has been found to be recommendable for routine analysis and the results have been satisfactory. The most of materials frequently employed in pharmaceuticals give no influence on the determination by this method except phosphate ion which forms precipitates with zirconyl ion and, precludes the measurement of the fluorescence. Development of fluorescence by several other metal salts than zirconyl chloride was also tested. However, no significant response with GL has been observed to the addition of these salts.

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An emission-spectrographic method is described for the quantitative determination of traces of non-rare earth elements separated from cerium dioxide by means of solvent extraction.
A 1.0 g sample of cerium dioxide is dissolved in a mixture of 5 ml of concentrated nitric acid and 5 ml of 30% hydrogen peroxide by heating on a water bath. The solution is evaporated to dryness. The residue is dissolved in 50 ml of 9N nitric acid containing 0.20 g of sodium bromate. The solution is extracted twice with 50 ml portions of tri-n-butyl phosphate. The aqueous layer is mixed with 0.10 g graphite powder, evaporated to dryness and finally heated at 500°C. To the residue thus obtained is added 10 ppm of gallium as an internal standard, and the whole is made up to 0.50 g by graphite powder. A weighed portion of this is placed on the sample electrode and packed lightly with a venting tool, and is discharged by d. c. arc.
Spectrographic conditions were as follow : 3.4 m Ebert grating spectrometer GEM-340; excitation voltage 220 V; arc current 15 A; analytical gap 2 mm; exposure time 20 sec without prc-burn; and anode charge 30 mg.
Recovery of impurity elements in the proposed analytical procedure was : 130% for Al and Mg; 90110% for Ag, Ca, Co, Cu, Mn, Ni, Pb and Sn; 5085% for Bi, Fe and Ti. Analytical values of impurities in the sample were corrected by the correction factor obtained from the recovery.
The proposed method enables the determination of microquantities of 13 impurity elements in cerium dioxide down to 0.2₅ ppm for Mg and Mn; 0.5 ppm for Ag, Bi and Cu; 2.5 ppm for Al, Ca, Fe, Ni, Pb and Sn; 5.0 ppm for Co; 12.5 ppm for Ti. Coefficients of variation are less than 15%.

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A serious problem in the analysis of metals in organic materials by atomic absorption spectrophotometry is that different compounds often give different absorbances. For example, a serious problem in the analysis of gasolines for tetraalkyl lead additives by atomic absorption spectrophotometry is that different lead compounds show different absorbances (Fig. 5). In the work discrived below, calcium, barium, zinc, copper, lead, vanadium and nickel compounds were examined, and the addition of various halogens and halides was found to be effective (Table III).
Similar problems have arisen in the determination of iother metals in organic materials by atomic absorption spectrophotometry. The determination of metal containing additives in oil blends was investigated by Mostyn and Cunningham, who diluted the sample with n-heptane and compared with standards prepared from an authentic additive and zinc naphthenate. The determination of nickel, iron and copper in crude petroleum oils was studied by Barras; again samples were diluted with n-heptane and compared with standards prepared from organometallic compounds. However, difficulties are encountered with all these methods, because different metal compounds yield different responses. This defect for analysis of gasoline can be avoided by the addition of halogen or halides to the gasoline solutions diluted with methyl isobutyl ketone (MIBK) ; under these conditions, a single calibration curve can be used for a wide variety of lead-containing additives, whether organic or inorganic, which require different curves otherwise.
The simultaneous addition of two or three halogens was studied. The recorder trace for a solution of calcium phenate in MIBK is shown in Fig. 8. It can be seen that the effect of iodine was decreased by bromine or chlorine, and that of iodine and bromine was decreased by chlorine (reactivity : iodine <bromine<chlorine). For example, when chlorine was added to the calcium sample followed by iodine or bromine, the absorbance of calcium was influenced by chlorine rather than by iodine or bromine.
The reaction of halogen and metal was studied by using a polyethylene atomization chamber equipped with two atomizers and a ultraviolet spectroscopic method (Fig. 913). As the results, it was found that these effects shown here could not be due to physical factor, such as viscosity and surface tension of the solution, acetylene pressure, characteristics of aspiration chamber, or reactions in solvents, but to some chemical reaction occurring in the flame.
The effect of halogen or halides on the atomic absorption of metal compounds was considered to be caused by the formation of metal halogen compounds in the flame (Fig. 14, 15).
This universal standard method for atomic absorption spectroscopy has proved remarkably effective for all the cases so far examined, and it should also be applicable to other organometallic and inorganic compounds.

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A method was presented for the spectrographic determination of lead and manganese in air borne particulates which were collected on Toyo No. 5c sequential filter tape every one hour by a tape air sampler.
5 sample circulars, prepared by cutting in 4 mm diameter from the filter paper, were placed in the crater of a graphite cup electrode of 4 mm diameter and 5 mm depth. A definite volume (50 μl) of internal standard solution containing 10 ppm indium was added dropwise. After drying, a spectroscopic buffer mixed 1 portion of sodium carbonate with 6 parts of graphite powder was packed the cup level full. Standard sample electrodes were prepared in the same fashion by dropping standard solutions containing lead, manganese and indium on Toyo No. 5c filter papers. The prepared electrodes were subjected to DC arc excitation (current 10 amp, analytical gap 3 mm).
Moving-plate studies indicated that no vaporization of lead and manganese occured during the first 15-sec period when the background was high. Then the vaporization started and continued during the next 30 sec of arcing. The background becomed to the minimum during this period. Thus the maximum line to background ratio was obtained by a 30-sec exposure after 15-sec pre-burn. Linear calibration lines were obtained over a range of 0.36.0 μg Pb/ m³ air and 0.061.20 μg Mn/m³ air. Variation coefficients for lead and manganese were 14.5% and 8.1% respectively.
In the present method, the procedures to prepare the electrodes from the procured samples were much simplified. Thus a rapid and more accurate analysis of lead and manganese in air borne particulates could be made by this method.

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Potentiometric titration with a primary standard solution of sodium oxalate was investigated to apply for the standardization of a glacial acetic acid solution of lead tetraacetate.
The solution of lead tetraacetate in which 4050 vol.% acetic acid was added to avoid the hydrolysis of lead tetraacetate during the titration course, was used as a titrated solution.
The titration procedures are as follows:
Into a 200 ml beaker, 3040 ml of glacial acetic acid and 10.00 ml of 10^-1 10^-3N lead tetraacetate were mixed, diluted to about 100 ml with distilled water, and titrated with a standard solution of sodium oxalate at an appropriate concentration. A platinum wire electrode as an indicator electrode and a saturated calomel electrode as a reference electrode, connected through a 30% KNO₃ agar bridge to the beaker, were used. The electrode potential after each addition of the titrant, was read within 12 minutes before and after the end point and within 23 minutes in the vicinity of the end point.
A considerable potential drop, 300400 mV per 0.10 ml of the titrant, was observed in the vicinity of the end point. Lead tetraacetate over the concentration range from 10^-110^-3 N could be determined within the error of about ± 1% and with the relative standard deviation of ± 0.1%, by titrating 50 vol.% acetic acid solution of lead tetraacetate with the standard solution of sodium oxalate.
The titration results under the proposed conditions were not affected by the change in concentration of acetic acid, pH, and temperature of the titrated solution within the range investigated.
This potentiometric method is easy and useful, as compared with the indicator method, for the standardization of a glacial acetic acid solution of lead tetraacetate.

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Trace amounts of cadmium in water can be concentrated on an anion exchange resin in alkaline medium, and easily desorped with dilute acid. The adsorption equilibrium constant for tetracyanocadmate (II) anion on sulfate-form of Amberite IRA-400 was found to be about 4×10⁴, whereas those of cyanide and chloride were about 25. The photometric determination of cadmium with dithizone combined with adsorption on an anion exchanger is as follows : Add 0.5 g of resin to 1 liter of 0.001 mol/l or more cyanide solution and stir for more than 2 hours for adsorption. Desorption is carried out with 0.1 mol/l acetic acid by 30 minutes stirring. Evaporate the eluate until less than 10 ml, transfer into 30 ml test tube. Add 2 ml of 0.25 mol/l potassium cyanide, 2 ml of 5.0 mol/l sodium hydroxide, 5 ml of 5×10^-4 mol/l dithizone anion, and then extract with 5 ml of chloroform. Wash the organic phase with 20 ml of 0.5 mol/l sodium hydroxide containing 1 drop of potassium cyanide. Repeat the washing until the aqueous phase indicates the color of dithizone anion that is equivalent to 1×10^-5 mol/l. In the case of extraction of cadmium dithizonate into chloroform, the extraction of cadmium decreases with an increase in the concentration of dithizone anion. By the proposed method, several microgram of cadmium in a litter sample water can be determined with about 80% recovery. Also a rapid photometric method for cadmium in a cyanide solution was investigated. To determine 220 μg of cadmium in the less than 0.01 mol/l of cyanide, add 2 ml of 0.2 mol/l formaldehyde as a masking agent to 10 ml of sample solution and develop the color with dithizone in sodium hydroxide solution. Cadmium reacts with dithizone to form a red color, probably ion-association adsorption compound in strong alkaline medium, namely greater than 0.5 mol/l hydroxide ion. This method is applied when the sample contains only cadmium and cyanide ions.

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Beryllium reacts with 5-hydroxychromone and its thirteen derivatives to form yellow complexes, which are soluble in various organic solvents. These complexes, except those of 2-methyl-8-iodo-and 2-methyl-8-nitro-5-hydroxychromone, exhibit yellow green fluorescence. The highest absorbance is obtained in benzene or chloroform, whereas the fluorescence with the greatest intensity in carbon tetrachloride. When the complexes are extracted at pH 7.08.0, the maximum and definite fluorescence intensity is observed, which does not alter for at least four hours. The effect of substituent groups in the ligands on the fluorescence behavior of their complexes was examined.
The absorption spectra and the fluorescence excitation and emission spectra are given in Fig. 14. When these spectra of the complexes of substituted 5-hydroxychromones are compared with those of 5-hydroxychromone, a following tendency is recognized : For 2-alkyl derivatives, peaks shift slightly toward the shorter wavelength; For 3-alkyl derivatives they are identical or shift slightly toward the longer wavelength; For 7-methoxy derivatives they shift considerably toward the shorter wavelength.
The relative fluorescence intensities in carbon tetrachloride and benzene are listed in Table II (Excitation wavelength : 405 mμ mercury line) and Table III (366 mμ). The fluorescence intensity changes markedly with the introduction of some substituents. When the complexes are excited at 405 mμ, a great increase in the fluorescence intensity is obtained by inserting alkyl groups (ethyl>methyl) into position 2 and/or 3 (2>3). The fluorescence intensity of the complex of 2-ethyl-3-methyl-5-hydroxychromone is about ten times of that of 5-hydroxychromone. When the complexes are excited at 366 mμ, that of 2-methyl-7-methoxy-5-hydroxychromone shows the greatest intensity. But it can not be concluded that the methoxy group in the position 7 increases the fluorescence quantum efficiency, for the excitation maximum of this complex is shorter than that of the others and, in addition, the intensity of 366 mμ mercury line is stronger than that of 405 mμ.
During these studies, it is considered that 2-ethyl-3-methyl-5-hydroxychromone (excitation : 405 mμ) and 2-methyl-7-methoxy-5-hydroxychromone (366 mμ) are suitable as the reagent for the fluorometric determination of beryllium. A detail of the method of determination with the former was reported in the preceding paper.

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An apparatus has been studied, which measures the lifetimes of activated fluorescent molecules etc. in the region of nanosecond by applying a sampling technique. High voltage (-2200 V) was supplied to the cathode of photomultiplier 56 AVP/03, and the multiplier gain was about 3.4×10⁷. The dynode chain resistors and the decoupling capacitors were carefully fixed, and the potentials of electrode g₁ and a_cc to the photocathode were adjusted in order to obtain the most satisfactory collection of photoelectrons and the smallest transit time fluctuations (the most homogeneous extraction fields). Small transient oscillation and good frequency response are obtained consequently. Trigger pulse is sent out from the 14th dynode, and lead to the pulse amplifier. Signal pulse is sent out from the anode, and delayed about 150 nsec through the cable 10DBTXE. Then they are lead to the sampling oscilloscope SAS 500. Signal pulses are transformed into low frequency signals by the oscilloscope, lead to the log ratio circuit, and recorded on X-Y recorder.
The impulse response was delivered by Cerenkov radiation. Rise time of the response is 2.6 nsec, and F. W. H. M. is 3.8 nsec. A pulse, F. W. H. M. of which is large than about 3 nsec, is able to be measured.
The liquid scintillation is measured when β ray of ¹⁴C radiates the scintillator (Toluene 1 l + PPO 4g+ POPOP 0.1 g). The peak height maximum is about 250 mV (R = 25 Ω) high. The lifetime of the fast component is 3.6 nsec, and that of the slow component is about 18 nsec. They agree with Ludwig's data. The amplitude of the transient oscillation is smaller than 1% of the main peak height, and the frequency is about 130 MHz. If the anode output of photomultiplier is larger than 1 mV, the measurement of the decay curve is possible.
When the scintillation of Nal (Tl) with the radiation of ¹³⁷Cs was measured, the energy resolution of photopeak was 12.7%. If P. H. of the anode output is larger than about 20 mV, signal pulses are able to be distinguished from thermionic noises considerably. This apparatus delivers three kinds of noises, they are thermionic noises of photomultiplier, noises at the preamplifier of the oscilloscope, and D. C. drift at the hold circuit. The last term is the most significant of the three, and the voltage (peak to peak) is about 23 mV at the stage of the hold circuit output.

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Furfural and pentose (D-xylose, L-arabinose and D-ribose) gave a specific fluorescence with anthrone in strong sulfuric acid.
In this paper, anthrone was used as a reagent for fluorometric determinations of furfural and pentose. Several conditions for the determination, such as excitation and emission spectra of anthrone-complexes, the concentration of anthrone, the acidity of sulfuric acid, the effect of reaction time and standing time, and the composition of fluorescent complex were investigated.
The maximum excitation and emission wavelengths of furfural and pentose are at 465 nm and 505507 nm respectively. The recommended procedures for quantitative determination were as follows. Ten milliliter of anthrone reagent (containing 0.01 w/v% of anthrone in 65 v/v% sulfuric acid) was added to 1 ml of pentose solution (2 ×10^-5 1 × 10^-4 mol), with continuous cooling in crushed ice water. The mixture was heated for 15 minutes in boiling water, then cooled for 10 minutes in crushed ice water, and it was reduced to room temperature.
The fluorescence intensity of the solution was measured at 505 nm by using a uranine solution (0.15 μg uranine/ml) as the reference standard.
The calibration curve was linear for 1 ×10^-6 1× 10^-5 mol (1.515 μg/ml) of furfural and pentose in 11 ml of final solution. The compositions of fluorescent complexes of anthrone-furfural and anthroneribose were determined by mole ratio method, and it was found that the 1 : 1 complexes were formed in both cases at above mentioned conditions.
This fluorescence reaction was specific for furfural and pentose. The relative fluorescence intensities (excitation; 465 nm, emission; 505 nm) of furfural, pentose, methyl-pentose and hexose were determined. The results obtained were as follows; furfural; 100, D-xylose; 98, L-arabinose; 66, D-ribose; 67, L-rhamnose; 3, L-fucose; 4, D-glucose; 12, D-galactose; 10, D-mannose; 10, D-fructose; 11, L-sorbose; 11. The fluorescence intensities of L-fucose, D-glucose, D-galactose, D-mannose, D-fructose and L-sorbose were far weaker than that of pentose (D-xylose, L-arabinose and D-ribose), and they were negligible for fluorometric determination of pentose. Therefore, this method was recommended for the determination of furfural, xylose, arabinose and ribose in methyl-pentose, aldo-hexose and keto-hexose.

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Lanthanum was titrated with constant current coulornetric method to form the complex with fluoride ion which was generated through a europium doped lanthanum fluoride single crystal membrane.
The fluoride ion activity electrode (Orion Co. # 90-09) was applied to the fluoride ion generating electrode. The effective area of the lanthanum fluoride single crystal is about 0.8 cm². The catholyte (1M NH₄F-HF) was circulated into the generating electrode to feed fluoride ion, and a platinum wire cathode was fitted to it. A piece of platinum wire was applied to the counter electrode, and saturated potassium nitrate was used as anolyte. A membrane of cation exchange resin was used to the counter electrode chamber to prevent leakage of fluoride ion.
The endpoint was detected potentiometrically with another fluoride ion activity electrode (Orion Co. #90-09A), and a saturated calomel electrode with salt bridge was used for reference electrode. These electrodes were set up to a polystyrene vessel in which 15 ml of electrolyte was filled. For the electrolyte 0.3M potassium nitrate-50% ethanol solution was experimentally selected. The titration curves were recorded with an automatic recording titration, and the results were directly given on the chart.
0.4 to 1.4 mg of lanthanum as chloride was titrated by this method with 1.6 to 2.5% of relative standard deviation. The current efficiency was 100.7± 1.6% at 15 mA/cm² of the current density in the electrolyte above mentioned. Lanthanum could be titrated over again without exchange of the electrolyte, until the electrolyte was extremely diluted with the sample solutions. The arrangement of the electrodes affected the titration curves, because the generating current caused electrical field in the electrolyte. The current efficiency was determined for 930 mA/cm², but high current density, such as 15 mA/cm², caused damage of the lanthanum fluoride membrane, and it needed too long titration time at low current density. The membrane may be cracked thermally by the heat formed from ohmic loss of the membrane. Therefore it is necessary to produce the electrode which has large membrane area or to reduce the specific resistance of the membrane.
This method expected to have applications to other cations which form stable fluoride complexes and other ion selective electrodes may be also applied to the specific ion generating electrode.

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On microdetermination of organic halogen using a silver boat, it has been found that chlorine and bromine are determined satisfactorily but an excess of silver causes a large negative error in analysis of iodine.
The authors investigated the stability of silver iodide in hot fuming nitric acid, the effect of an amount of silver on the recovery of iodine, the reduction of silver iodate to iodide, a suitable weight of silver boat, heating time and other analytical conditions.
Silver iodide was unstable in hot fuming nitric acidand produced silver iodate or liberated iodine. Silver iodate dissolved slightly in nitric acid solution and the recovery of silver iodide decreased in proportional to the amount of added fuming nitric acid. By an addition of silver, the recovery of it increased, but it decreased again when silver was added in a large excess. It was assumed that a complex was formed by an absorption of the excess silver ion on the silver iodide precipitates and it was dissolved in nitric acid solution.
Various amounts of silver (1035 mg) were used in order to determine the adequate weight of silver boat which made the negative error minimum, and 25 mg was found to be appropriate.
Iodate ion was found in the solution in which an iodine compound had been thermally decomposed with fuming nitric acid and silver and it was considered one source of the negative error. It is not decomposed by only heating on a boiling water bath. Therefore the reduction of it to iodide by sodium nitrite solution was tried. Four mg of silver iodate and 10 mg of silver nitrate were dissolved in 1 ml of conc. nitric acid and 3 ml of distilled water, the solution was added 4 ml of 1M sodium nitrate solution and heated on a water bath. More than 99% of silver iodide was recovered.
The most suitable conditions are as follows. About 4 mg of sample is weighed in a silver boat of 2025 mg and put it into a sealed glass tube. After an addition 0.5 ml of fuming nitric acid, the whole is heated at 310320°C for 3 hours. Then 5 ml of distilled water is added and heated on a boiling water bath for 90 minutes. After cooling to the room temperature, 2 ml of 1M sodium nitrite solution is added and heated on a water bath for 120 minutes. Then filtered, dried and weighed.
By this method good results were obtained for the determination of iodine in standard ο-I-benzoic acid and Iodcform. The standard deviations were 0.14₉ and 0.24₇, respectively.

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Cadmium was extracted from 0.5N hydrobromic acid solution with 1 vol.% tri-n-octylamine or trioctylmethylammonium chloride in methyl-isobutyl ketone (MIBK), and quantitation of cadmium in the organic solvent layer was directly performed.
In order to know the optimum experimental conditions, various factors such as the settings of the instrument, the conditions of the extraction, etc. have been studied.
The optimum conditions were found as follows. Wavelength 2288Å, hollow cathode lamp current 6.5 mA, slit width 0.2 mm, air pressure 1.4 kg/cm², and acetylene pressure 0.3kg/cm².
The absorbance became about 2.5 times higher than that of the complex in aqueous solutions. The method was applied to the determination of trace amounts of cadmium in water, soil and rice and the results were found satisfactory in comparison with DDTC method.

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An attempt was made to determine of sulfur in organic compounds in one-tenth the scale of the existing microanalytical method. Examination were made on the sample is burnt by the flask incineration method and the amount of sulfate ion formed is determined by titration observing electric conductivity. The volume of titration solution and the effect of titration rate, and the limit of detect were examined by the use of a 2-ml burette. It was thereby found that the determination is possible with samples containing more than 25 μg of sulfur, with good precision comparable to the existing microanalytical method.

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A half gram of sample was treated with hydrofluoric acid, sulfuric (1+ 1) acid and perchloric acid to remove silica, and then total iron and aluminum was separated by centrifugation after the precipitation with ammonia (1 + 1). The precipitate was dissolved in 6N hydrochloric acid and the solution was passed through a column of Amberlite IRA 410 in order to separate aluminum from iron. The effluent was evaporated to dryness, and was stood for cooling. The dilute hydrochloric acid and the aluminon solution were added in this solution. The solution was heated on a water bath at 100°C for 10 minutes. After 30 minutes the absorbance at 537.5 mμ was measured against water as the reference. The results of analysis agreed well with those by the JIS method. The error was within 1% with good reproducibility and accuracy of values.

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The adsorption of 18 cations on a silica-alumina adsorbent (containing 2.70% aluminum and treated at 500°C) has been determined by a batch method. The adsorption was found to be larger in the order Ba²⁺>>Pb²⁺ >Fe³⁺>Hg²⁺>Al³⁺>Ni²⁺>Sr²⁺>Sn²⁺> Cd²⁺>Co²⁺>Zn²⁺>Mn²⁺>Ca²⁺>Cu²⁺>Ag⁺> K⁺>Na⁺>Mg²⁺. The capacity of this adsorbent was 5 to 10 times larger than that of silica gel treated at 300°C. The capacity is larger when the ionic charge or the ionic radius is larger and among metal ions in the same periodic group, it is larger as the atomic number increases.

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The mechanism of the Voges-Proskauer reaction was investigated using 1-phenyl-1, 2-propanedione (I), morpholinoamidine (II), α-naphthol in the presence of alkali (Barritt's method) and uisng (I), (II) in the presence of alkali (O'Meara's method).
The pigments obtained by Barritt's method and O'Meara's method were isolated as crystals by column chromatography.
From the data of NMR and mass spectra, the structures of pigments obtained by Barritt's and O'Meara's method were determined as 2-(2-morpholino-4-phenyl-1H-5-imidazolylmethylidene) 1, 2-dihydro-1-oxonaphthalene (VI) and 2-morpholino-5-phenyl-4-(2-morpholino-4-phenyl-1H-5- imidazolylmethylidene) isoimidazol(VII), respectively. Structures of 2-(2-morpholino-4-methyl-1H-5-imidazolylmethylidene)-1, 2-dihydro-1-oxonaphthalene (III) and 2-morpholino-5-methyl-4-(2-morpholino-4-methyl-1H-5-imidazolylmethylidene)-isoimidazol (IV) were determined previously by NMR, mass and IR spectroscopy.
On the other hand, 2-morpholino-4-hydroxy-4-methyl -5-phenyl-4-isoimidazol (V) was obtained as a solid, from the reaction mixture of (I) and (II) in N₂.
(VI) and (VII) were also derived by the reaction with (V) and α-naphthol-sodium hydroxide solution and the reaction with (V) and sodium hydroxide solution in air, respectively.
These results indicate the Voges-Proskauer reaction proceeds through (V), which is followed by the production of (VI) and (VII).

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