ABSTRACT
In this study, we developed a simple method that enables iron(III) in environmental water to be directly determined via spectrophotometry. In water samples, iron(III) formed a yellowish complex with N-1-Naphthylethylenediamine dihydrochloride (NEDA) at pH 2.0-2.8, the maximum absorption wavelength of which was 462 nm. Detection sensitivity increased in the presence of chloride ions and remained constant for 2-24 h with 0.05-0.57 mol L-1 chloride. Therefore, NEDA solution containing chloride ions was used as a chromogenic reagent for the determination of iron(III). The determination range for this method was 0.1-20 mgFe(III) L-1 in a 5 cm glass cell. The developed method is highly selective for iron(III) and has been successfully applied to freshwater, brackish water, seawater, turbid water in rivers, as well as to riverbed and freshwater lake sediments. In addition, a combination of the proposed NEDA method and the 1,10-phenanthroline method enabled simultaneous determination of iron(III) and iron(II).
ABSTRACT
Nanomolar concentrations of NH2OH in natural water sources were determined using an Fe3+ oxidation method. A pH of 2.35 - 2.50 was used, which was adjusted by adding a chloroacetate buffer. Equal amounts (1.0 mL) of the chloroacetate solution and ferric chloride solution were added to the water sample (70 mL) to oxidize NH2OH to N2O. The resulting N2O in the sample water was then quantified by headspace analysis using a gas chromatograph with an electron-capture detector (ECD), where a limit of detection of 0.2 µgN L-1 (14 nmol L-1) was achieved. This method was successfully applied to samples of freshwater, brackish water, and seawater, and despite the various salinities no interfering substances were observed. Furthermore, NH2OH was successfully detected in samples collected from the Hii River and Lakes Shinji and Nakaumi (Shimane Prefecture, Japan). In addition, the proposed method was also applicable to samples rich in organic substance derived from phytoplankton.
ABSTRACT
We developed a method for quantifying trace NH2OH in brackish- and sea-water samples. Previously reported methods applicable to fresh water cannot be applied to such samples. We determined that interference in seawater owing to the bromide ion can be removed by the addition of phenol. In our procedure, phenol and hypochlorite solutions were added to a sample solution to oxidize NH2OH to N2O. N2O in the sample was then quantified by headspace analysis. The method is not affected by the salt content or ammonia, nitrate, or nitrite at concentrations of 300 µgN L-1 or less. It has a limit of detection of 0.2 µgN L-1, and can quantify NH2OH in natural water samples with a wide range of salinity. It was applied to samples from Lake Nakaumi, a brackish lake located in the eastern part of Shimane Prefecture, Japan.
ABSTRACT
A simple and rapid in situ method for the determination of hydrazine based on the concentration of aldazine compound formed by the reaction of hydrazine with p-dimethylaminobenzaldehyde was developed. This method was based on solid-phase extraction using a Sep-Pak C18 cartridge, followed by the quantification of hydrazine using a spectrophotometric method. To a sample solution of environmental water, p-dimethylaminobenzaldehyde solution was added to form aldazine by the reaction with hydrazine. The solution was passed through a Sep-Pak C18 cartridge for the adsorption of aldazine. In the laboratory, the aldazine adsorbed on the Sep-Pak C18 cartridge was eluted by passing a hydrochloric acid-ethanol (1:10) solution through the cartridge, and the color intensity of the solution was measured at 457 nm. The limit of detection for the new method was 0.2 mgN L-1 of hydrazine. The determination of hydrazine in solution was not influenced even by hydrogen sulfide and organic matter. This method was then applied to the brackish water of Lake Nakaumi in the eastern area of Shimane Prefecture, Japan. This method was used to determine hydrazine in freshwater, seawater and wastwater.
ABSTRACT
A method for determination of hydrogen sulfide in microsamples (200 µL) was developed by modifying the methylene blue method. Samples were collected using a micropipette and were combined with sulfide coloring reagent and 5 mL of 0.1 M HCl in test tubes. Absorbance of the solution was measured spectrophotometrically at 667 nm. This modified method did not require any special labware or technique, and can be used in a variety of research fields.
ABSTRACT
Gicerin is a cell adhesion molecule in the immunoglobulin (Ig) superfamily and plays an important role during development through its adhesive properties. Gicerin has two isoforms that differ in their cytoplasmic domains; s-gicerin is the shorter and l-gicerin the longer form of the protein. Gicerin is over-expressed in some sporadic tumors as well as in developing tissues. To provide direct evidence that gicerin has the potential to participate in malignant aspects of tumor cell behavior, a gicerin cDNA was introduced into L-929 cells, an endogenous gicerin-negative mouse fibroblast and subsequently analyzed for changes in their invasive and metastatic potential by implantation into nude mice and chick embryos. Compared with parental cells, both gicerin isoform transfectants showed an enhanced cell growth and invaded deeply into surrounding tissues from implanted sites in both animal models. Furthermore, l-gicerin transfectants markedly enhanced metastasis to the lung. These findings suggest that gicerin promotes the tumor growth and invasion, and the isoform bearing the longer cytoplasmic domain may play a role in metastasis.
