Development of absorption spectrophotometry of iron(III) in environmental water and sediments using NEDA and its application to the field.

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.

A new method for phosphate purification for oxygen isotope ratio analysis in freshwater and soil extracts using solid-phase extraction with zirconium-loaded resin.

Rationale: Phosphate (PO ) oxygen isotope (δ O ) analysis is increasingly applied to elucidate phosphorus cycling. Due to its usefulness, analytical methods continue to be developed and improved to increase processing efficiency and applicability to various sample types. A new pretreatment procedure to obtain clean Ag PO using solid-phase extraction (SPE) with zirconium-loaded resin (ZrME), which can selectively adsorb PO , is presented and evaluated here.

Sensitive Gas Chromatography Detection of Nanomolar Hydroxylamine in Environmental Water by Fe(III) Oxidation.

Nanomolar concentrations of NHOH in natural water sources were determined using an Fe oxidation method. A pH of 2.35 - 2.

Sensitive Method for the Oxidation-determination of Trace Hydroxylamine in Environmental Water Using Hypochlorite Followed by Gas Chromatography.

We developed a method for quantifying trace NHOH 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.

Determination of Trace Hydrazine in Environmental Water Samples by in situ Solid Phase Extraction.

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.

High spatial resolution analysis of the distribution of sulfate reduction and sulfide oxidation in hypoxic sediment in a eutrophic estuary.

Bottom hypoxia and consequential hydrogen sulfide (HS) release from sediment in eutrophic estuaries is a major global environmental issue. We investigated dissolved oxygen, pH and HS concentration profiles with microsensors and by sectioning sediment cores followed by colorimetric analysis. The results of these analyses were then compared with the physicochemical properties of the bottom water and sediment samples to determine their relationships with HS production in sediment.

Colorimetric Determination of Sulfide in Microsamples.

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.