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Kanda, Yukio; Oki, Yuichi; Endo, Akira; Numajiri, M.; Kondo, Kenjiro

doi:10.1023/a:1006790309473

Cited by 9 publications

(1 citation statement)

References 14 publications

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“…The generated NO was swept from the gas-liquid separating coil into an NOx monitor by a room-air freed of NO by passing through a filter immersed with cobalt(III) oxide. 13,14 In an analysis of seawater, the sample was pretreated prior to loading in the FIA system. A 10 ml portion of 1.0 M NaOH solution was added into a 100 ml sample.…”

Section: Methodsmentioning

confidence: 99%

Flow-Injection Analysis Method for the Determination of Nitrite and Nitrate in Natural Water Samples Using a Chemiluminescence NOx Monitor

Kanda

Taira

2003

ANAL. SCI.

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The determination of nitrite and nitrate in aqueous environmental samples is of considerable interest in research concerning hydrological chemistry, chemical oceanography, and atmospheric chemistry. Nitrate is an essential nutrient which controls the biomass in natural water; the amount also indicates the extent of pollution and eutrophication of the aquatic environment. Nitrite is a nitrogen-cycle intermediate and a useful indicator of the equilibrium state of the oxidative and reductive pathways of the nitrogen cycle. Also, nitric acid and nitrous acid are very important trace constituents of the atmosphere in both the gaseous and particulate phases. Nitric acid is a major NOx sink in photochemical air pollution. Nitrous acid is recognized as a major source of a very reactive hydroxyl radical, which is a key intermediate for all photochemical oxidant formations. These gases and particulates are precursors of acid rain, and are deposited on the ground mainly by wet precipitation, such as rain and snow.Among many analytical methods proposed for the determination of nitrate and nitrite, a widely used method for analyses of natural water samples is based on the reduction of nitrate to nitrite and a subsequent spectrophotometric determination via the Griess reaction, 1-3 which involves the diazotization of sulfanilic acid and successive coupling with 1-naphthylamine. Though numerous modifications have been suggested, primarily based on changing either the reagent being diazotized or coupled, sulfanilamide or sulfanilic acid and N-(1-naphtyl)ethylenediamine are the most popular couples. 4,5 The spectrophotometric method can provide reliable results for natural water samples, but suffers from interferences from suspended and colored substances in the samples. Cox 6 proposed a chemiluminescence analysis technique, which is more highly sensitive and free from these interferences. The technique is based on the chemical reduction of nitrate and nitrite to NO and detection via a chemiluminescence reaction of NO with ozone. Garside 7 first applied this technique to seawater analyses. Braman and Hendrix 8 reported on an application used for environmental water samples. These methods used NaI for reducing nitrite to NO, and iron(II)-molybdate or vanadium(III) for reducing nitrate to NO. The reduction procedures in these methods require highly acidic conditions and/or operation at a relatively high temperature. In the monitoring method of ambient gaseous HNO2, 9 we employed ascorbic acid in a dilute H2SO4 for reducing nitrite to NO. This reagent is easy to handle and the reaction is rapid and quantitative at low nitrite levels. By reducing nitrate to nitrite with an alkaline hydrazine solution, the measurement system was further developed to a gaseous HNO3 monitoring method. 10The coupling of the chemiluminescence detection with a flowinjection technique (FIA) would permit the development of sensitive, precise, rapid, and high throughput methodologies having a wide dynamic range. Aoki and Wakabayashi 11 reported a chemilumine...

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Section: Methodsmentioning

confidence: 99%