A method based on the principle of flow injection analysis (FIA) is proposed for the determination of chemical oxygen demand (COD) in waste waters from laboratories containing large amounts of organic COD substances. The FIA apparatus was constructed of commercially available parts for high performance liquid chromatography. Polytetrafluoroethylene tubing (0.5 mm i.d.) was used for a reaction chamber and mixing coils as well for connections betweenthe assemblages. By using test solutions including glucose as a standard material for COD, operating conditions and parameters for the FIA method were examined and fixed as follows; both of 4.9 × 10^-4 M potassium permanganate and 6.7 % sulfuric acid solutions were separately pumped up with a double reciprocating micro-pump and merged into a carrier stream. At just before the merging place, a 20 μl of sample solution was injected into the flow of sulfuric acid solution. The sample mixed with the carrier solutions was passed through a boiling water-bath and led to a flow cell for the absorbance measurements at 525 nm. The absorbances were continuously recorded with time. The peaks in the recordings showed good reproducibility at a concentration range of (24220) mg COD 1^-1. The detection limit and precision confirmed with this method were 10 mg 1^-1 and 0.5 %, respectively. Chloride ion up to 7000 mg 1^-1 did not interfere with the COD determination without adding silver sulfate. By the present method, properly diluted waste water samples were analyzed at a sampling rate of 30 samples per hour and the results were compared with those obtained by the JIS method. Both of the methods gave the same results within an error range of ±30 %.

View full abstract

An inductively coupled plasma-optical emission spectrometry (ICP-OES) forthe determination of phosphorus in water samples was studied. The extent of the interferences of the spectral lines from argon, NO emission and stray light for the analytical line was investigated in detail and the best experimental conditions were established. No spectral line interferences from matrix elements were observed for the second order line of P I 213.62 nm, while the spectral lines from argon at 427.22 nm and NO emission overlapped with the analytical line, giving rise to the positive interferences. The spectral intensity of the former increased at higher temperature part of the plasma, that is, at the off-axis part of the plasma and lower observation height above load coil, and the latter increased at the center and fringe of the plasma. These spectral line interferences were able to be minimized by optimizing the source parameters as follows: RF power (1.4 kW); argon gas flowrate: plasma gas (1.2 1/min), coolant gas (10.3 1/min) and carrier gas (1.0 1/min); and observation height (12 mm above load coil). The interference from stray light was also observed for the analytical line. The spectral back ground level increased rectilinearly with increasing the concentration of magnesium: the presence of 1000 ppm of magnesium gave an interference equivalent to 2 ppm of phosphorus. The interference of magnesium was able to be easily eliminated by a preliminary cation-exchange procedure. With the optimal conditions, a preactical detection limit of 0.13 ppm was achieved and the method established was applied to the determination of phosphorus in water samples in comparison with colorimetric method in good agre ement.

View full abstract

A simple and rapid method for the determination of nitrite and nitrate ions in ambient waters was developed by high performance liquid chromatography. Porous silica type anion exchange packing material (Partisil-10 SAX) was useful for the separation of these ions. Nitrite and nitrate ions were eluted with 0.005 M buffer solution of KH₂PO₄-Na₂HPO₄ (pH 6.4) and detected at UV 205 nm. The height equivalent to a theoretical plate for nitrate ion was 0.04 mm and peak resolution between nitrite and nitrate ions was about 5 for the column of 25 cm × 4.6 mm i.d. The calibration curves were linear up to 50 ng. One thousand ppm of phosphate ion, sulfate ion and 100 ppm of anionic surface active agent did not interfere with the determination, while more than (100200) ppm of chloride ion did. Several samples of river water were analysed by this method and (0.63.6) ppm of nitrite and (4.420) ppm of nitrate ions were found. The analytical time for one sample was about ten min. In the case of sea water, the interference caused by chloride ion was removed by dissolving 1 g of sodium chloride in 11 of eluent to makethe concentration of 0.017 M. The recovery of nitrate ion (2 ppm) added to standard sea water was 97.4 % and the coefficient of variation was 2.3 %. Several samples of sea water were found to contain (0.20 0.76) ppm of nitrite and (0.713.49) ppm of nitrate ions by this method.

View full abstract

Little has been done by electron probe X-ray microanalyzer on the analysis of oxygen in inorganic oxides of heavy elements like lanthanoids. In this work direct determination of oxygen by electron probe X-ray microanalyzer in double oxides of lanthanoid and niobium (LnNbO₄; Ln=La, Pr, Gd, Er, Tb) was carried out. The relative intensity ratios k=I/I_STD were determined with accelerating voltages in the range of (520) kV. Alumina was used as the oxygen standard. As the oxygen K_α line is in the long wavelength region, the correction for absorption is the most important among the ZAF corrections. Three correction methods, simple Philibert, full Philibert and Yakowitze-Heinrich correction were compared. The atomic number correction by Duncumb-Reed was also applied. No fluorescence correction was made since the X-ray fluorescent yielded was very small in this study. It was found that the full Philibert treatment gave the best agreement with the theoretical value at all the measured accelerating voltages with the accuracy of 4.76 %. With the lower voltages {(57) kV}, however, Yakowitze-Heinrich treatment gave better results. The L/B ratios (Line intensity/Background intensity) were found maximum at about (1012) kV. The accuracy of the oxygen analysis was 2.85 % when measurement was made this accelerating voltage and the full Philibert absorption and the Duncumb-Reed atomic number correction were applied.

View full abstract

A gas chromatographic method was studied for the determination of micro amount of glyoxal in water and sediment by use of the reaction of glyoxal with 4-chloro-ο-phenylenediamine giving rise to 6-chloroquinoxaline quantitatively. This method was applied to determine glyoxal in tap water, river water, industrial waste water and sediment. To 100 ml of a water sample in a 200 ml separatory funnel was added 2 ml of 50 % (w/v) hydroxylammonium chloride and 10 ml of hydrochloric acid, and the solution was washed with 40 ml of benzene. The water layer was transferred to a 200 ml flask, added with 5 ml of 0.1% 4-chloro-ο-phenylenediamine, and heated at 90°C for one hour under a reflux condenser. After cooling to room temperature, the reaction mixture was extracted with two 40 ml portions of benzene. The combined extract was washed twice with 50 ml portions of distilled water, dried over anhydrous sodium sulfate, and filtered. The resulting solution was concentrated or diluted with benzene, if necessary, for gas chromatographic determination. In case of sediment samples, a mixture consisting of (2030) g of a sediment, 3 ml of 50 % (w/v) hydroxylammonium chloride and 150 ml of distilled water was shaked for 150 min in a 300 ml Erlenmeyer flask with ground stopper. After filtration, 10 ml of hydrochloric acid was added to 100 ml of the filtrate, and the solution was treated in the same way as the case of water sample. The gas chromatographic conditions were as follows: column packing, 2 % DEGS on Gas chrom Q 80/100 mesh; column size, 3 mm i.d.×2 m glass column; column temperature, 130 °C; injection and detector temperature, 180°C; carrier gas, nitrogen, 40 ml/min; detector, ECD (⁶³Ni). The recoveries of the overall performance of this method were (9199)% for water samples and 89% for sediment samples. The minimum determinable amounts of glyoxal were 1 ng/ml in water and 0.02 kg/g in sediment.

View full abstract

A rapid and sensitive method for the determination of lead by hydride evolution-atomic absorption spectrometry was investigated by using two types of gas handling systems; one of them involves gaseous hydride to be introduced directly into a slot burner (N₂-H₂ flame, type A generator) and the other to be collected in a reservoir followed by introduction to the burner (type B generator). To attain high sensitivity of the method, a combined use of potassium dichromate, hydrogen peroxide, or persulfate with sodium borohydride was essential in both types of hydride generator. In the nitric acid-hydrogen peroxide-borohydride system, when applied to the type A generator, the sensitivity was dependent of the initial reaction temperature from 20°C to 65°C and was enhanced twice at 65 °C. However, this technique could not be applied to the complex samples containing iron(III) and the other foreign ions. Though instability of the lead hydride was confirmed with the type B generator, the collection time was not so critical between 15 s to 30 s. This merit improves the relatively severe determination conditions required with the type A generator. The detection limit (S/N=2) and reproducibility of the method (0.05 M HNO₃-0.4 M Na₂S₂O₈-0.13 g NaBH₄, type B generator) based on ten determinations of 0.5 μg Pb(II) were 10 ng and 2.9 %, respectively. The proposed method was applied successfully to the standard rocks (JB-1, JG-1), standard steels (JSS 159-3, 160-3, 161-3) and water samples.

View full abstract

Trace quantities of chlorine, bromine and iodine in a pure selenium metal were simultaneously determined by radiochemical neutron activation analysis. The analytical procedure employed was based on the mutual separation of halogens by using distillation and solvent extraction with CCl₄, and subsequent activity measurement with a Geiger Mueller counter. This paper describes not only the decontamination factor for the radiochemical separation used but also the possible nuclear interference such as a second order reaction induced from the selenium matrix. The detection limit for each halogen was 0.003, 0.008 and 0.001 ppm for Cl, Br and I, respectively. The typical results obtained for halogens in the high purity selenium (99.999 %) were 0.4 ppm Cl, 0.03 ppm Br and 0.02 ppm I.

View full abstract

An amperometric titration was developed for the determination of hydroquinone and p-methylaminophenol. The reduction current of potassium iodate (titrant) at a rotating platinum electrode (2000 rpm) was measured at +0.6 V vs. SCE. Both the relative deviation and the coefficient of variation are less than 0.1 %. Hydroquinone (4 ×10^-5 M to 4 × 10^-3 M) could be rapidly titrated at about 10 °C with 0.05 ml portions of potassium iodate standard solution at intervals of 5 s (0.05 ml/5 s) in the presence of hydrochloric acid. The titration required only 3 min. p-Methylaminophenol sulfate (10^-4 M to 10^-3 M) could be titrated at about 25 °C with potassium iodate standard solution (0.05 ml/10 s) in the presence of hydrochloric acid and sodium chloride. The titration required about 5 min. The presence of sodium sulfite, sodium carbonate, potassium bromide and sodium tetraborate did not interfere with the titration. The recommended procedures are as follows. Place 10 ml of 2 × 10^-3 M hydroquinone or 10^-3 M p-methylaminophenol sulfate in the titration cell. For the analysis of hydroquinone, add 20 ml of 10 M hydrochloric acid and dilute to 50 ml with water. For the analysis of p-methylaminophenol sulfate, add 10 ml of 10 M hydrochloric acid and 10 g of sodium chloride and dilute to 50 ml with water. Titrate the resultant solutions with 10^-2 M potassium iodate standard solution amperometrically.

View full abstract

Solvent extraction of vanadium(V) with N-cinnamoyl-N-(2, 3-xylyl)hydroxylamine(CXA) was investigated spectrophotometrically. Vanadium(V) is extracted with CXA from (3.59) M hydrochloric acid solution into chloroform as a violet complex which. shows an absorption maximum at 535 nm. The ex tracted complex, in which the vanadium : CXA ratio is 1 : 2, is stable over a long period. Beer's law is obeyed over the range (0.57)μg/ml of vanadium in organic phase. The molar extinction coefficient is 6600 1 mol^-1 cm^-1 at 535 nm. The interferences from iron(III) and titanium(IV) can be eliminated by adding phosphoric acid and sodium fluoride, respectively. The proposed method was applied to the determination of vanadium in petroleum. The results are in good agreement with those obtained by the atomic absorption spectroscopy.

View full abstract

The determination method of inorganic and bound sulfate in human urine and serum was investigated in detail with a sulfate ion analyzer, and the following procedure has been established: For the determination of inorganic sulfate in urine, 10 μl of 5-fold diluted urine with deionized water was applied directly to the column. For the bound sulfate, 0.5 ml of 5-fold diluted urine was transferred to 1 ml of glass ampoules and to this 0.25 ml of 3 N HCl was added. After heating the sealed ampoule for 60 min at 100 °C, the mixture was taken into a centrifuged tube. Then, 200 mg of Ag₂O was added to the tube and it was centrifuged for 5 min. Ten μl the supernatant solution was applied to the column, and the amount of total sulfate was measured. The amount of bound sulfate was calculated by the difference between the amounts of total sulfate and inorganic sulfate. For the determination of inorganic sulfate in serum, 0.5 ml of serum was diluted to 1 ml with deionized water and to this 0.5 ml of cold 20 % trichloroacetic acid (TCA) was added. After 10 min the mixture was centrifuged for 15 min and 100 μl of the supernatant solution was applied to the column. For the bound. sulfate, 0.5 ml of above supernatant solution was transferred to 1 ml of glass ampoules and 0.25 ml of 3 N HCl was added. The sealed ampoule was heated for 120 min at 100 °C. Later procedure was as same as the determination of bound sulfate in urine, and 100μl of the supernatant solution was applied to the column. Recoveries of inorganic and bound sulfate for human serum and urine by the present method were satisfactory, in (98.4403.6) % and (99.3100.6) %, respectively. The average amounts of inorganic and bound sulfate in serum of normal persons (n=8) were 3.43 mg/dl {(3.043.76) mg/dl} and 1.50 mg/dl { (1.141.99) mg/dl}, respectively, which are agreeable with the other data. The amounts of inorganic and bound sulfate in urine varied greatly.

View full abstract

A simple and rapid semiquantitative procedure has been developed for the determination of ppm level of total heavy metal ions in environmental aquatic samples using an analytical column packed with reagent gel beads. Reagent gel beads were prepared by treating the cross-linked polystyrene beads {2 % divinylbenzene, (70100) mesh in dry condition} with 0.01% chlorobenzene solution of 1-(2-pyridylazo)-2-naphthol (PAN) for 24 h at room temperature. The gel beads were packed into a glass column (2.5 mm bore, 120 mm length). When sample solution, buffered to pH 10 with NH₃-NH₄Cl containing tartrate, was passed through the PAN gel column at a flow rate of 0.2 ml/min, the original yellow color of the reagent gel turned to red or red-violet from the up-stream of the column, if the sample contained lead, cadmium, copper (II), cobalt(II) or zinc. As the length of colored band was proportional to the total moles of heavy metal ions in the sample solution passed through the column, the total concentration of heavy metal ions can be determined from the calibration line which had been prepared by using the standard solution. When the sample solution containing heavy metal ions at (120) μM level was passed through the column at 0.2 ml/min for 4 min, the length of colored band was (10400) mm, and the determination could be done with (± 5±10) % relative errors. Alkali metals, alkaline earth metals, iron(III), aluminum, chromium (III), silver and mercury(II) did not interfere. Nickel and manganese(II) did not give clear color reaction. This method was successfully applied to the analysis of total heavy metal ions in environmental aquatic samples.

View full abstract

The molecular absorption spectra of some metal salts of manganese, vanadium, chromium, molybdenum and tungsten in an air-acetylene flame were measured in the wavelength range from 200 nm to 400 nm and the extent of the interferences of these spectra for analytical lines of other elements by atomic absorption spectrometry was investigated. A Hitachi 207 atomic absorption spectrophotometer with a deuterium lamp, a laboratory-made lamp, and some hollow cathode lamps as the light sources was used for the measurements of the absorption spectra. The maximum absorptions of these band spectra were obtained at 256.0 nm and 375.0 nm for manganese, 293.4 nm and 297.6 nm for chromium, 242.5 nm and 344.7 nm for molybdenum, and 243.7 nm and 302.3 nm for vanadium, respectively. Each peak for these maximum absorp tions coincided in position with that for the band spectra obtained by emission spectrometry with the air-acetylene flame. These spectra, which have not yet been reported, are presumably due to metal oxides and hydroxides produced in the flame. The spectral interferences from the solutions of 1.0% or 1.2 % metal salts were observed as the absorption errors of as much as (346) times relative to the sensitivity obtained for Zn, Cd, Ni, Fe, Mn, Cu and Cr by atomic absorption spectrometry. The spectral interferences from nitric, sulfuric and phosphoric acids were also observed in the wavelength range from 200 nm to 350 nm.

View full abstract

The derivative spectrophotometry was applied to the determination of iron at ppb levels. The apparatus used was an automatic recording spectrophotometer equipped with an analogue differentiation unit, and 2, 4, 6-tris(2-pyridy1)-s-triazine was used as a coloring agent. Under the recommended conditions, a linear relationship was confirmed between 2nd derivative value and iron concentration. According to the pro posed method, about 25 ppb of iron in drinking water can be determined easily and rapidly without any preconcentration treatment.

View full abstract

The sensitizing effect of 16 quaternary ammonium salts on the spectrophotometric determination of germanium with phenylfluorone was compared. Benzalconium chloride gave the greatest increase in sensitivity: under the optimum conditions the sensitivity was about twice as high as that in the absence of this salt, the molar extinction coefficient of the complex formed being 1.81×10⁵ dm³ mol^-1 cm^-1 at 508 nm. The calibration curve was linear up to 0.16 ppm of germanium. Metal ions such as As³⁺, As⁵⁺, Pb²⁺, Hg²⁺, Cu²⁺, Al³⁺, Fe²⁺, Fe³⁺, Cd²⁺, and Zn²⁺ did not interfere with the determination, while Sb³⁺, Sn²⁺, Sn⁴⁺, and Mo⁶⁺ gave positive errors.

View full abstract

Inorganic arsenic (arsenite and arsenate), disodium methanearsonate (DSMA) and dimethylarsinic acid (DMAA) were extracted into benzene from the hydrochloric acid medium with or without potassium, iodide. The extractability was estimated by determining the arsenic, after transferring it from benzene into water by back-extraction, with an atomic absorption spectrophotometer equipped with a graphite furnace atomizer. Inorganic As(III) was the only species extracted with benzene alone although the extraction was not complete. Above (56) M in hydrochloric acid containing potassium iodide (0.5 M), essentially 100 % of both As(III) and As(V) were extracted. Ion-exchange chromatography, thin-layer chromatography and molybdenum blue formation reac tion revealed that the greater part of As(III) and As(V) were extracted as As(V) in the presence of potassium iodide. Essentially 100 % of DSMA was extracted from the hydrochloric acid {(39.6) M} containing potassium iodide (0.5 M). A maximum extraction of DMAA was achieved from the (78) M hydrochloric acid medium containing potassium iodide (0.1 M or 0.5 M). The percent extraction, however, did not exceed ca. 90 %. Although the distribution ratio of DMAA between the benzene and aqueous (7 M hydrochloric acid, 0.5 M potassium iodide) phases was about 10, those of other three arsenicals were of the order of nearly 10². This procedure was useful for separation and purification of water-soluble arsenic compounds present in the extract of a brown seaweed, Hizikia fusiforme.

View full abstract

The infrared reflection spectrometry was applied to the quantitative analysis of the organic compounds on metal surface by using a Fourier transform infrared spectrometer equipped with a triglycine sulfate detector. The light reflection system was made by authers. Samples were thin layers of organic compounds formed on the aluminum surface. A good linearity was obtained between the peak intensity (ΔR/R) and the quantity of the organic compound. In the case of cinnamic acid, the linearity was observed when the thickness was less than about 5μg/cm². The detection limit of cinnamic acid was 0.2μg/cm² (about 2 nm thick) by the one-reflection method. This limit would be improved by the use of a photoconductive infrared detector.

View full abstract

The proposed method is to extract arsenic(III) by benzene as its pyrrolidinedithiocarbamate (PDTC), back-extract arsenic with dilute bromine water and to determine arsenic as its molybdenum heteropoly blue. The method could be applied to determine ppm levels of arsenic in environmental samples with deviation of ±0.2ppm. Tin, bismuth, and molybdenum interfered seriously, but these metal ions amounting 4 times, 20 times, and 1.5 times for arsenic could be permitted, respectively. Treat (0.51) g of a sample with nitric acid and (45) ml of conc. sulfuric acid. After destruction of organic matter with nitric acid, expel the acid by heating to fumes of sulfuric acid. Dissolve the treated mass with water in hot, filter of insoluble matter and dilute the filtrate to 100 ml with water. To this add some ascorbic acid and 0.2 g of thiomalic acid, and heat the solution at temperature near boiling for 10 min to obtain arsenic(III). To extract arsenic(III) from the solution with 20 ml of extractant (5 v/v % ethanol-benzene solution of 0.1 w/v % PDTC-ammonium salt), and remove the excess of the carbamic acid from the organic extract by shaking with 2 w/v % NaHCO₃solution. Obtain arsenic in aqueous solution with 4 ml of dilute bromine water successively with 3 ml of water. With the combined extract, prepare a molybdenum heteropoly blue complex in a volume of 10 ml and measure the absorbance at 840 nm with a spectrophotometer using 1 cm cells.

View full abstract

Metalloenzyme (alkaline phosphatase) dissolved in lake water has been identified by means of high performance liquid chromatography (HPLC). Water samples were collected from Shinobazu-no-ike Pond (Tokyo) and Lake Kasumigaura (Ibaraki), and filtered with a 0.45μm Millipore filter just after sampling. Filtered water was concentrated to (5001000) fold by ultrafiltration, where ultrafiltration membrane (Amicon UM-10) which concentrated the components of molecular weight larger than 10000 was used. The enzymatic activity of alkaline phosphatase was measured using p-nitrophenyl phosphate as a substrate. Addition of EDTA (ethylenediamine tetraacetic acid) to the concentrated lake water did not show any enzymatic activity, while the enzymatic activity was recovered with addition of zinc ion. The HPLC chromatograms of the concentrated lake water were examined, where an aqueous porous gel column W-71 from Shimadzu Co. Ltd., was used for separation. According to the chromatorams, the effluent at 12.2 min was corresponding to alkaline phosphatase. The final identification was made by adding E. coli alkaline phosphatase to the concentrated lake water and by measuring the liquid chromatogram. Zinc was also found in the fraction of the effluent between 11.3 and 12.3 min. More details of the experiments will be published in near future.

View full abstract

The complexometric method for gallium in Cu-(2040)% Nb-(16)% Ga alloys was developed. Sample was dissolved in nitric acid and hydrofluoric acid. After adding sulfuric acid, the solution was heated, evaporated to SO₃ fume, and then cooled. The salts were dissolved in water, copper and niobium were precipitated by bromine water and sodium hydroxide. A small amount of dissolved niobium in the filtrate was masked by the mixture of 10 ml of 47 % hydrofluoric acid and 200 ml of saturated boric acid solution. After adjusting pH at33.5 by sodium acetate, gallium was titrated with EDTA at > 90°C using Cu-PAN as indicator. In the presence of niobium (<1 mg), copper and gallium was determined by back titration of excess EDTA with zinc (II) solution using Xylenol Orange involving the masking of copper with thiourea.

View full abstract

A method was proposed to solve some difficult problems in a quantitative analysis of carbon dioxide in nitrogen by a gas chromatography-mass spectrometry. The stability of the output of a mass spectrometer was improved by measuring spectra of reference gas and sample gas within 6 min and comparing peak areas of the spectra. A Faraday cup was superior to a secondary electron multiplier as a detector of a mass spectrometer for a quantitative analysis. The effect of nitrogen gas to the mass spectrometer was avoided by applying negative voltage to a repeller electrode, when nitrogen gas eluted from a gas chromatograph to an ion source of a mass spectrometer. With this technique that we have established the concentration of carbon dioxide in nitrogen is analyzed quantitatively from 100 % to ppm order with very high accuracy and precision. The minimum concentration of carbon dioxide that can be analysed by the present method depends on not only the dynamic range of the mass spectrometer but also the leakage of atmospheric carbon dioxide through a sampling valve and the noise level of the picoammeter.

View full abstract