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Determination of nitrate in sea water by cadmium-copper reduction to nitrite

  • E. D. Wood (a1), F. A. J. Armstrong (a2) and F. A. Richards (a1)
Abstract

An accurate, dependable determination of 0–60 μg-at./l. of NO3-N in sea water has been developed. The sample is treated with tetrasodium ethylenediaminetetraacetate solution and passed through a column of copperized cadmium filings. A nearly quantitative reduction of nitrate to nitrite results. Nitrite is then determined by a diazotization method. Neither sulphide nor high nitrite concentrations interferes. Approximately eight samples per hour per column can be analysed with a standard deviation of 0.12 μg-at./l. at the 20 μg-at./l. level.

Introduction

Accurate determinations of nitrate ions in sea water have been difficult, especially under shipboard conditions.

The colorimetric method described by Harvey (1926, 1930) and improved by Cooper (1932), Zwicker & Robinson (1944), and others uses strychnidine in concentrated sulphuric acid to produce a red colour. The reagent lacks reliable sensitivity, because it is dependent on the rates of mixing and cooling.

In a method by Armstrong (1963), the absorbance of nitrosyl chloride in the UV region is measured with a spectrophotometer. While the method is good for small samples containing high concentrations of nitrate, the use of concentrated sulphuric acid and lack of sensitivity limit its use in routine analysis.

A method in which nitrate is quantitatively reduced to nitrite would be advantageous, because nitrite can be readily determined by the sensitive diazotization method proposed by Griess (1879). Several such methods have been proposed. FØyn (1951), Vatova (1956), and Chow & Johnstone (1962) used zinc powder for the reduction, but the reduction is sensitive to temperature, and it is necessary to centrifuge or filter each sample.

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References
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Armstrong F. A. J., 1963. The determination of nitrate in water by ultra-violet spectrophotometry. Analyt. Chem., Vol. 35, pp. 1292–4.
Austin K. H. & Strickland J. D. H., 1959. The direct estimation of ammonia in sea water with notes on ‘reactive’ iron, nitrate, and inorganic phosphorus. J. Cons. perm. int. Explor. Mer, Vol. 24, pp. 446–9.
Bendschneider K. & Robinson R. J., 1952. A new spectrophotometric determination of nitrite in sea water. J. mar. Res., Vol. 11, pp. 8796.
Brewer P. G. & Riley J. P., 1965. The automatic determination of nitrate in sea water. Deep-Sea Res., Vol. 12, pp. 765–72.
Chow T. J. & Johnstone M. S., 1962. The determination of nitrate in sea water. Analytica chim. acta, Vol. 27, pp. 441–6.
Cooper L. H. N., 1932. The determination of nitrate in the sea by reduced strychnine. J. mar. biol. Ass. U.K., Vol. 18, pp. 161–6.
Flaschka H. A., 1959. EDTA Titrations. New York: Pergamon Press. 138 pp.
FØyn E., 1951. Nitrogen determinations in sea-water. FiskDir. Skr., Ser. HavundersØk., Bd. 9, No. 14, pp. 17.
Grasshoff K., 1964. Zur Bestimmung von Nitrat in Meer- und Trinkwasser. Kieler Meeresforsch., Bd. 20, No. 1, pp. 511.
Griess P., 1879. Bemerkungen zu der Abandlung der H. N. Weselsky und Benedikt ‘Uber einige Azoverbindungen’. Ber. dt. chem. Ges., Bd. 12, pp. 426–8.
Harvey H. W., 1926. Nitrate in the sea. J. mar. biol. Ass. U.K., Vol. 14, pp. 7188.
Harvey H. W., 1930. Nitrate in the sea. II. J. mar. biol. Ass. U.K., Vol. 15, pp. 183190.
Morris A. W. & Riley J. P., 1963. The determination of nitrate in sea-water. Analytica chim. acta, Vol. 29, pp. 272—279.
Mullin J. B. & Riley J. P., 1955. The spectrophotometric determination of nitrate in natural waters with particular reference to sea water. Analytica chim. acta, Vol. 12, pp. 464–80.
Pötzl L. & Reiter R., 1960. Eine einfache Methode zur Bestimmung von NitratIonen im atmospharischen Niederschlag und in Aerosol-Kondensaten mit Anwendungauf Probleme der Luftelektrizitat wahrend Niederschlagen. Z. Aerosol Forsch. u. -Ther., Bd. 8, pp. 252–64.
Shinn M. B., 1941. A colorimetric method for the determination of nitrite. Ind. Engng Chem., analyt. Edn, Vol. 13, pp. 33–5.
Strickland J. D. H. & Parsons T. R., 1965. A manual of seawater analysis, 2nd ed. revised. Bull. Fish. Res. Bd Can., No. 125, 203 pp.
Vatova A., 1956. Elektrophotometrische Nitratbestimmung im Meerwasser mit dem Photometer ‘Elko II’. Dt. hydrogr. Z., Bd. 9, pp. 194–8.
Zwicker B. M. G. & Robinson R. J., 1944. The photometric determination of nitrate in sea water with a strychnidine reagent. J. mar. Res., Vol. 5, pp. 214–32.
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Journal of the Marine Biological Association of the United Kingdom
  • ISSN: 0025-3154
  • EISSN: 1469-7769
  • URL: /core/journals/journal-of-the-marine-biological-association-of-the-united-kingdom
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