The method celdas

Celdas method - method for the quantitative determination of nitrogen in organic compounds.
Nitrogen organic compounds by heating with concentrated sulphuric acid in the presence of catalysts converted into ammonium sulphate; organic matter completely destroyed. Out of ammonium sulfate concentrated alkali displaced ammonia, which Argonauts in the receiver with a certain amount titrated acids. Having measured after distillation the number of remaining in the receiver acid, calculate the amount of ammonia in the sample and therefore, the amount of bound nitrogen in the studied object. Kjeldahl method is only applicable for analysis of substances, where nitrogen is associated with carbon or hydrogen. Substances, in which nitrogen is associated with oxygen (e.g., nitrates, nitrites, and so on), you must first restore to amines (see).
Kjeldahl method is used to determine protein and non-protein nitrogen-containing substances in food, tissues and body fluids, to estimate the number of bound nitrogen excreted with urine, faeces, to determine the residual nitrogen in the blood and so on
Cm. also Nitrogen, residual Nitrogen.