PURPOSE: To measure quantitatively nitric acid or nitrate ion concentration simply and precisely by measuring the electromotive force of a microorganism electrode to which the microorganism is adhered having a nitric acid respiration activity in the vicinity of a diaphgram of carbonic acid gas electrode.
CONSTITUTION: Fungus 2 of the microorganism having nitrate respiration activity is applied on a carrier 3 and placed on a dissolved carbonic acid gas electrode diaphgram 1, and it is coated by a dialysis film 4 having small pores which do not pass microorganism such as cellophane, in an internal liquid (for example, NaHCO3- NaCl mixed solution), pH electrode 5 is placed to form a microorganism electrode 7. As a carrier 3, nylon. mesh filter paper etc. is used. This microorganism electrode 7 is contacted with the liquid to be tested under the air repellent condition, and by the electromotive force produced, nitric acid or nitrate ion concentration is measured.
HIKIMA MOTOHIKO
YASUDA TAKEO
