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16. Ozone gas-phase chemiluminescence for silane and its application to the determination of silicate in natural waters

Author

Fujiwara, Kitao, Uchida, Masayuki, Chen, Min-min, Kumamoto, Yu-ichiro, and Kumamaru, Takahiro

Subjects
Chemiluminescence -- Methods, Silane -- Research, Water chemistry -- Analysis, Silicates -- Spectra, Chemistry
Abstract

Chemiluminescence emission generated by mixing silane with ozone was investigated for the determination of silicate in natural water. This chemiluminescence spectra extends 400-850 nm providing a maximum at 600 nm. Chemiluminescence spectra obtained by mixing diborane and ozone were also shown. For the purpose of generating silane from the aqueous solution of silicate, the following procedure was adopted: The sample solution was dried and mixed homogeneously with powdered lithium aluminum hydride in a Teflon tube or a molybdenum boat. When this mixture was heated at 200C, 97 [+ or -] 3% of silicate in the sample was reduced to silane. After the generated silane was collected in the trap, the silane was mixed with ozone, and chemiluminescence was detected directly by a photomultiplier. The calibration curve was linear from 1 to 500 [mu]g Si, and the detection limit was 0.5 [mu]g of Si for this method. Phosphorus and arsenic give the positive interference, which is, however, negligible for the practical analysis of natural waters. The analytical results for river waters and seawaters (the Tokyo Bay and the North Pacific Ocean) are in good agreement with those confirmed by molybdenum yellow colorimetry.

Published
1993

20. Characterization of Marine Photochemical Processes in the Seto Inland Sea, Japan

Author

Hiroshi Sakugawa, Kawai Hiroshi, Hirata Shizuko, Faculty Integrated Arts, Takeda Kazuhiko, Hiroshi Kawai, Akira Takami, Takami Akira, Kazuhiko Takeda, Kitao Fujiwara, Sakugawa Hiroshi, Ohta Keiichi, Keiichi Ohta, Shizuko Hirata, and Fujiwara Kitao

Subjects
chemistry.chemical_compound, Organic peroxide, chemistry, Sample point, Environmental chemistry, Diurnal temperature variation, Inorganic chemistry, Seawater, Diurnal change, Photochemistry, Hydrogen peroxide, Surface water, Carbon monoxide
Abstract

Temporal and spatial variations of hydrogen peroxide, organic peroxide, carbon monoxide, Fe(III) and Fe(II), which are crucial species to control the photochemical processes in coastal seawater, are investigated in the western part of the Seto Inland Sea on May 15-19, 1995. Concentrations of hydrogen peroxide and carbon monoxide wee higher at the surface and decreased with depth, while the vertical distributions of organic peroxide and soluble Fe(II) were found to be almost uniform or a little higher at the bottom layer. Soluble Fe(III) increased with depth and the concentrations at the sampling point near the mouse of the river were higher than those far from river and land, suggesting that suspended matter supplied from river and bottom of the sea was the source of soluble Fe(III). Concentrations of hydrogen peroxide, carbon monoxide and soluble Fe(II) in surface water tended to increase with solar radiation. Especially, diurnal variation of carbon monoxide was clearly in accordance with solar radiation. These results strongly suggest the photochemical formation of hydrogen peroxide, carbon monoxide an soluble Fe(II) in the surface and near-surface waters. Diurnal change of organic peroxide was the reverse of that, the concentrations of organic peroxide in the daytime were lower than those during the nighttime.

Published
1999

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