Method for determining total nitrogen in tobaccos and tobacco products by automatic water steam distillation titrator

The invention discloses a method for determining total nitrogen in tobaccos and tobacco products by an automatic water steam distillation titrator. The method comprises the following steps: (1) drying a tobacco sample; grinding and sieving the tobacco sample; sealing into a brown glass bottle to obtain a test sample; (2) weighing the tobacco test sample and putting the tobacco test sample into a digestion pipe; adding an oxidant, a catalyst and a warming agent; putting the digestion pipe into a digester to digest the tobacco test sample and cooling to obtain a blue-green clarified transparent digestion solution; (3) putting the digestion pipe containing the digestion solution into a digestion pipe frame of the automatic water steam distillation titrator; adding distilled water and sodium hydroxide into the digestion pipe; (4) adding boric acid solution containing an indicator into an indicator storage tank of the automatic water steam distillation titrator; and (5) calculating volumes of inorganic acid standard solutions consumed by a blank test sample and the tobacco test sample respectively to obtain the content of the total nitrogen in the tobacco test sample. According to the method disclosed by the invention, only a simple working solution needs to be prepared in a detection process and the procedures of making up the volume of the digested test sample and preparing a lot of other working solutions are saved, so that the detection efficiency is improved.