Reference substance for titration of ammonium salt absorbed in boric acid solution

Abstract

The invention discloses a reference substance for titration of ammonium salt absorbed in a boric acid solution through a Kjeldahl determination method. The reference substance has the advantages of stable property and large mole quality, the purity can achieve 99.95%, and the reference substance is subjected to a quantification reaction with the ammonium salt absorbed in the boric acid solution. The reference substance is dried at the temperature of 105 DEG C to a constant weight, is directly weighed, and is slightly heated with high pure water for dissolving to prepare 0.01 mol / L of a standard solution, the standard solution is used for titration of the ammonium salt absorbed in the boric acid solution, and the total nitrogen content of a sample is measured. The nitrogen recovery rate ofthe 0.01 mol / L of the standard solution prepared by the reference substance is 98.10-100.28%, the average nitrogen recovery rate is 99.42%, and the coefficient of variation is 0.81%. Compared with general standard acidimetry, a tedious calibration work is omitted, the analysis precision is increased, and the determination result is accurate and reliable.

Description

Technical field [0001] The invention relates to the field of chemistry, in particular to a reference substance capable of titrating the ammonium salt absorbed in a boric acid solution in the Kjeldahl method. Background technique [0002] Kjeldahl method is an important method to determine the nitrogen content of nitrogen-containing organic matter. At present, the Kjeldahl method is still used as the standard method to detect the nitrogen content of organic matter in my country's national standards and international standard methods. The principle is: the plant or organic fertilizer sample is subjected to H 2 SO 4 -H 2 O 2 Digestion; the soil sample is in the catalyst (K 2 SO 4 -CuSO 4 -Se) is used for digestion with sulfuric acid; after the sample is digested with sulfuric acid, the organic nitrogen-containing compounds are oxidized and decomposed into ammonium sulfate, and the ammonia is absorbed in the boric acid solution by alkali distillation, and then titrated with a standard...

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