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A nitrate test is a chemical test used to determine the presence of nitrate ion in solution. Testing for the presence of nitrate via wet chemistry is generally difficult compared with testing for other anions, as almost all nitrates are soluble in water. In contrast, many common ions give insoluble salts, e.g. halides precipitate with silver, and sulfates precipitate with barium. The nitrate anion is an oxidizer, and many tests for the nitrate anion are based on this property. Unfortunately, other oxidants present in the analyte may interfere and give erroneous results. ==Ring test== A common nitrate test, known as the brown ring test〔Egon Wiberg, Arnold Frederick Holleman (2001) ''Inorganic Chemistry'', Elsevier ISBN 0-12-352651-5〕 can be performed by adding iron(II) sulfate to a solution of a nitrate, then slowly adding concentrated sulfuric acid such that the acid forms a layer below the aqueous solution. A brown ring will form at the junction of the two layers, indicating the presence of the nitrate ion.〔Mascetta, Joseph A. Barron's ''How to Prepare for the SAT II: Chemistry'', 7th edition. Barron's Educational Series, Inc., 2002. p208.〕 Note that the presence of nitrite ions will interfere with this test.〔Holltzclaw, H; Robinson, W. ''College Chemistry with qualitative analysis'', 8th edition, D. C. Heath and Company:Lexington, MA, 1988, p. 1007.〕 The overall reaction is the reduction of the nitrate ion by iron(II) which is oxidised to iron(III) and formation of a nitrosonium complex where nitric oxide is oxidised to NO+. :NO3− + 3Fe2+ + 4H+ → 3Fe3+ + NO + 2H2O :()2+ + NO → ()2+ + H2O 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「nitrate test」の詳細全文を読む スポンサード リンク
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