QUANTITY DETERMINATION METHOD OF TOTAL NITROGEN

PROBLEM TO BE SOLVED: To determine the quantity of total nitrogen in examination water up to a high concentration area through simple operation by utilizing diazotization reaction caused by nitrite ion.SOLUTION: A quantity determination method of total nitrogen in examination water includes a step 1 of adding alkali metal salt of peroxodisulfate to the examination water and heating the examination water from 90°C to its boiling temperature under alkalinity, a step 2 of adding vanadium chloride (III) and a diazotization reagent which reacts with nitrite ion to generate diazonium salt to the examination water having undergone the step 1 and heating the examination water under acidity, and a step 3 of measuring a nitrite ion concentration by measuring absorbance of coloration by the diazotization reagent or absorbance of coloration by the generated diazonium salt for the examination water having undergone the step 2. A chemical compound selected from among an aromatic primary amine compound group having a keton group or a nitro group and a 3-amino-2-cyclohexene-1-one skeleton-containing compound group is used as the diazotization reagent.