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Surface functionalized mesoporous silicates, MCM-41s, having 3-(2-pyridylmethylideneimino)propyl group (PI-MCM-41) or 3-(2-quinolylmethylideneimino)propyl group (QI-MCM-41) were prepared viaSchiff base reaction, and the adsorption behavior of metal ions onto the modified MCM-41s was investigated. The function groups on the modified MCM-41 surface were confirmed by Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and elemental analysis. The metal ions examined, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, and Pb2+, were quantitatively adsorbed on the PI-MCM-41 and QI-MCM-41, except for Mn2+. In the complexation with these metal ions, it was suggested that imine-N and heterocyclic-N atoms act as donor atoms. In addition, it was considered that the hydrophobicity derived from the organo-functional groups modified on MCM-41 contributed to improving the adsorption ability.

A simple and rapid in situpreconcentration method for the spectrophotometric determination of trace ammonia nitrogen in environmental water samples has been developed based on solid-phase extraction using a small column packed with octadecyl group-bonded silica gel (Sep-Pak C18 cartridge). A water sample was taken into a graduated syringe for easy and simple operation and prevention of contamination immediately after sample collection. Ammonia in the sample was reacted with hypochlorite and thymol to be converted into indothymol blue; then the formed indothymol blue was collected as an ion pair between indothymol blue and tetrabutylammonium ion on a Sep-Pak C18 cartridge. The indothymol blue on the cartridge was stable for 4 days. The retained indothymol blue was easily eluted with a mixture of methanol and 0.01 mol/l sodium hydroxide solution. The color intensity due to the indothymol blue was spectrophotometrically measured at 725 nm. The proposed method was successfully applied to environmental water samples such as river water.

A simple in situvisual and tristimulus colorimetric method for the determination of trace arsenic in environmental water after collecting arsenic on a test paper impregnated with mercury(II) bromide and rosaniline chloride by its reduction aeration has been developed. The color development on the test paper is based on the formations of AsH(HgBr)2(yellow) and/or As(HgBr)3(brownish yellow) by a reaction between mercury(II) bromide and arsine (AsH3), which is produced through the reduction of As(III) (arsenite ion) and/or As(V) (arsenate ion) in a sample solution. To a sample solution, potassium iodide, tin(II) chloride, zinc sand and 4 ml of 6 M hydrochloric acid solution were added successively. The liberated arsine was collected on the test paper. The yellow or brownish-yellow color intensity on the test paper was measured by a tristimulus colorimeter and also by a visual method. The established method is applicable to the determination of arsenic in environmental water sample such as river, brackish, and seawater types.

A new and simple method for the determination of hydroxylamine in environmental water, such as fresh rivers and lakes using hypochlorite, followed by its gas choromatographic detection, has been developed. A glass vial filled with sample water was sealed by a butyl-rubber stopper and aluminum cap without head-space, and then sodium hypochlorite solution was injected into the vial through a syringe to convert hydroxylamine to nitrous oxide. The head-space in the glass vial was prepared with 99.9% grade N2using a gas-tight syringe. After the glass vial was shaken for a few minutes, nitrous oxide in the gas-phase was measured by a gas chromatograph with an electron-capture detector. The dissolved nitrous oxide in the liquid-phase was calculated according to the solubility formula. The proposed method was applied to the analysis of fresh-water samples taken from Iu river and Hii river, flowing into brackish Lakes Nakaumi and Shinji, respectively.

A simple and rapid in situpreconcentration method for the determination of dissolved manganese in environmental waters has been developed based on solid-phase extraction using a Sep-Pak C18 cartridge. Manganese in water samples, which was taken into a graduated syringe to easily perform the operation for collecting manganese at sampling sites, was converted into a stable complex with 4-(2-pyridylazo)resorcinol (PAR) at pH 10 immediately after sample collection. The formed Mn-PAR complex was collected by a Sep-Pak C18 cartridge, which was packed with C18-bonded silica. The complex was stable in the Sep-Pak C18 cartridge for at least one month. The retained complex was quantitatively eluted with 0.5 M hydrochloric acid. The manganese was determined by graphite-furnace AAS. The proposed method was successfully applicable to brackish lake water samples to investigate the behavior of dissolved manganese in brackish lakes.

Abstract: Nitrous oxide (N2O) was measured monthly from September 1997 to August 1998 in the brackish Lakes Shinji and Nakaumi, Japan. N2O (5–37 μg N l−1) was supersaturated in the overlying water on lake sediments from October 1997 to January 1998. The N2O concentration in the hypolimnion was higher than that in the epilimnion on 17 October 1997, when N2O was first observed in a water column of Lake Nakaumi. Afterward, N2O was almost uniform throughout the water column and then disappeared on 16 February 1998. On the one hand, large amounts of N2O were found throughout the year in the interstitial water in Lake Shinji, where a high concentration of nitrate was discharged from the Hii River. On the other hand, in Lake Nakaumi, stratified by halocline, a high concentration of N2O was observed in the interstitial water only from winter to spring. N2O concentrations in the interstitial water were about 10 to 1000 times as large as those in the overlying water. These results imply that N2O was mainly produced at the sediment-water interface and was diffused to the overlying water. It was also suggested that the accumulation of N2O in the sediment-water system was accelerated by a high concentration of hydrogen sulfide.

Carbon disulfide and pyrrolidine containing p-xylene was proved to be useful and convenient for metal extraction. The procedure involved forming pyrrolidine dithiocarbamic acid during the course of extraction and solidifying the organic phase by cooling in a centrifuge. Metal ions such as Cd2+, Ni2+, Co2+, and Zn2+could be extracted into the organic phase without using any chelate extractant.

A simple and rapid method for the in situpreconcentration of trace dissolved sulfide in environmental water samples has been developed based on solid-phase extraction using Sep-Pak C18 cartridges. Dissolved sulfide in water samples, which was taken into a graduated syringe to prevent the oxidation of sulfide by air, was reacted with N,N-dimethyl-p-phenylene-diamine sulfate and iron(III) chloride to be converted into Methylene Blue immediately after sample collection. The formed Methylene Blue was adsorbed on Sep-Pak C18, which was stable on Sep-Pak C18 for at least 30 d. The adsorbed Methylene Blue was eluted with a mixture of methanol and 0.01 M hydrochloric acid. The color intensity due to the Methylene Blue was measured at 659 nm. The proposed method is applicable to brackish and sea water samples as well as freshwater.

By mixing carbon disulfide and diethylamine in chloroform prior to use, diethyldithiocarbamic acid forms. Such metal ions as Cu2+, Co2+, Zn2+, Ni2+, Cd2+, Fe3+, and Mn2+were quantitatively extracted from an aqueous sulfate medium as a diethyldithiocarbamate complex. The optimum extraction conditions, such as the pH, mixing ratio of reagents, and shaking time for equilibrium, were established.

The atomic ratio between C, H, O, N, Cl, Br, and I in an organic halogen compound was obtained satisfactorily by gas chromatography and ion chromatography. At first the atomic ratio between C, H, O, and N was determined simultaneously by PSGC and then the atomic ratio between a halogen atom and C, H, O, and N was obtained by estimating the amount of a halogen atom in the reaction residue and by calculating the weight percent in Eq. 4 by use of a correction factor and peak areas in gas and ion chromatograms.

An improvement has been made in the pyrolytic sulfurization gas chromatographic method, by which the atomic ratio between C, H, O, and N in a sample can be simultaneously determined. Analysis was carried out by use of the correction factors instead of calibration curves. Correction factors were obtained by use of five standard compounds, naphthalene, thiourea, cyanoguanidine, sucrose, and amidosulfuric acid. The method is simple, accurate, and applicable to various compounds.

A simple and rapid method for in situpreconcentration of iron(II) in environmental water samples has been developed, based on solid phase extraction using Sep-Pak C18 cartridges. Iron(II) in water samples, which was taken into a graduated syringe to prevent oxidation of iron(II) by air, was converted into a colored cationic complex with ferrozine (C20H12N4O6S2Na2) at pH 4.5 immediately after sample collection. The iron(II)-ferrozine complex was adsorbed on Sep-Pak C18 as an ion-pair with acetate ion. The complex was stable on Sep-Pak C18 for at least 3 weeks. The adsorbed complex was eluted with a mixture of acetone and 0.1 M hydrochloric acid. The color intensity due to the complex was measured at 562 nm. The proposed method is applicable to brackish and sea waters as well as fresh water.

A dextrane-polyacrylic acid mixture was found to be a good phase-separating agent for aqueous solutions and to be applicable to the solvent extraction of tris(1,10-phenanthroline)iron(II) ([Fe(phen)3]2+). Iron(II) was extracted as an ion- pair with polyacrylic acid. Such extraction conditions as the mixing ratio of two polymers, the pH, and the temperature during centrifuging were examined.

Simultaneous determination of the atomic ratio between C, H, O, and N in a metallo-organic compound containing transition element is possible by the pyrolytic sulfurization gas chromatographic method, addition of reducing agent being unnecessary. Analytical results of metallo-organic compounds depend on the characteristics of their metal oxides. A few organophosphorus compounds were analyzed. The formation of water could be predicted from the atomic ratio of carbon to oxygen in a compound.

In order to confirm whether or not pyrolytic sulfurization gas chromatography can be applied to organophos-phorus compounds, many kinds of organophosphorus compounds were examined; C-rich compounds gave satisfactory results while C-poor ones gave lower oxygen values. The application limit of this method to various organophosphorus compounds was determined by the use of the C/O value and a structural factor for a sample, and the application limit was established. The structural factor of a sample varied with the kind of X1, X2, X3, and X4in the general formula X1X2X3P=X4, where X1=OH, OR, R; X2=OH, OR′, R′; X3=OH, OR″, R″; and X4=O, S.

The halide produced from a halo-organic compound interferes with the simultaneous determination of the atomic ratio between C, H, O, and N in the compound by the pyrolytic sulfurization gas chromatography, but the interference can be eliminated by allowing the pyrolytic sulfurization of the compound to proceed in the presence of the sodium sulfide formed by the reaction between sodium azide and sulfur.

From a sample subjected to pyrolytic sulfurization in a sealed quartz tube, the evolved gases, carbon disulfide, carbon monoxide, carbon dioxide, carbonyl sulfide, hydrogen sulfide, and a nitrogen molecule were simultaneously estimated. Determination of the atomic ratio between C, H, O, and N was carried out by means of three calibration curves obtained by use of glycine, l-glutamic acid, l-citrulline, and fumaric acid. They are applicable to carboxylic acids and the other compounds, but not to compounds including nitro and/or sulfo groups.

In order to clarify the effect of the coexistent elements on the determination of the atomic ratio between C, H, O, and N by the pyrolytic sulfurization gas chromatography (PSGC), compounds containing 25 kinds of elements were investigated. Only 7 of these interfered the determination of the atomic ratio. Several organophosphorus, lithium-, and boron-containing compounds were also analyzed. The results obtained by the present work are summarized in the periodic table together with those from previous work.

The simultaneous determination of the atomic ratio between C, H, O, and N in various compounds including a metal organic chelate one has been presented in our previous papers. With the objective of reducing the analysis time, an apparatus by which a continuous and simultaneous determination of the atomic ratio between C, H, O, and N can be carried out has been newly designed and constructed. Using this apparatus, many samples can be treated continuously at the rate of about 20 min for one sample, with satisfactory results.

In order to use a hydrophilic solvent as an organic phase in liquid–liquid extraction by retaining it to a solid support, the occlusion and desorption of nine hydrophilic solvents, such as methanol, to three kinds of commercially available oil-adsorbent were examined. The combination of tetrahydrofuran and WOSEP made by fibrous polypropylene was finally selected, and was subjected to the extraction of alkaline earth metals with 8-quinolinol. It was proved that Mg2+, Ca2+, and Sr2+ions could be successfully extracted into the tetrahydrofuran phase in the form of 8-quinolinolato complexes, which could not be extracted into CHCl3.

Ein einfaches und wirkungsvolles Anreicherungsverfahren für Phosphat in wässriger Lösung beruht auf der Verwendung von Zr-beladener Aktivkohle (Zr-C*), die durch Vermischen (3 Tage) von 100 ml Zirkonylnitratlösung (1 g Zr, pH 1,6) mit 10 g Aktivkohle, Filtern und Trocknen hergestellt wurde. 10 g des Materials enthielten 0,5–0,6 g Zirkonium. Adsorption und Desorption von Phosphat sind nur vom pH-Wert der Lösung abhängig und erfolgen quantitativ bei pH < 8,0 bzw. pH > 13,5. Die wässrige Probelösung vom pH 1,5 wird durch das auf einem Membranfilterpapier befindliche Zr-C*-Bett gesaugt und das zurückgehaltene Phosphat durch Elution mit 40 ml 1 M NaOH-Lösung wiedergewonnen. Pyrophosphat, Tripolyphosphat und Metaphosphat verhalten sich ähnlich wie Orthophosphat.

The transition metals such as zinc, cobalt, nickel, and copper were extracted into a carbon disulfide-isoamylalcohol-pyridine ternary mixed solvent. The optimal pH ranges for extraction are 2.6-8.0 for copper, 7.9-8.5 for zinc, 2.0-2.6 for nickel, and 1.6-3.5 for cobalt, respectively.

Oxides of aluminium, silicon, and titanium, instead of the magnesium oxide used in the Bacon-Fanelli method, were found to be effective for the elimination of trace amounts of organic compounds in sulfur. Prolonged refluxing in an inert gas atmosphere were especially favorable for the removal of organic compounds