CONCENTRATION MEASUREMENT METHOD AND FUEL BATTERY SYSTEM

PROBLEM TO BE SOLVED: To provide a concentration measurement method that can accurately measure concentration of a hydrazine solution relatively high in concentration, and to provide a fuel battery system that includes concentration measurement means having the concentration measurement method employed.SOLUTION: A method of electrochemically measuring a hydrazine concentration in a hydrazine solution is configured to: bring a working electrode 51, counter electrode 52, and reference electrode 53 of an electrochemical measurement device 50 into contact with a hydrazine solution (a preparation process); sweep potential of the working electrode 51 in a positive potential direction to form an oxide coating film on a surface of the working electrode 51 (a coating film formation process); then, sweep the potential of the working electrode 51 in a negative potential direction and remove one part of the oxide coating film (a coating film removal process); and then, sweep the potential of the working electrode 51 in the positive potential direction, and measure the hydrazine concentration by detecting a current change relative to the sweeping (a concentration measurement process). 【課題】比較的高濃度のヒドラジン溶液の濃度を精度よく測定することができる濃度測定方法、および、その濃度測定方法が採用される濃度測定手段を備える燃料電池システムを提供すること。【解決手段】ヒドラジン溶液中のヒドラジン濃度を電気化学的に測定する方法において、ヒドラジン溶液に、電気化学測定装置５０の作用電極５１、カウンタ電極５２および参照電極５３を接触させ（準備工程）、作用電極５１の電位を正電位方向に掃引し、作用電極５１の表面に酸化皮膜を形成し（皮膜形成工程）、その後、作用電極５１の電位を負電位方向に掃引し、酸化皮膜の一部を除去し（皮膜除去工程）、その後、作用電極５１の電位を正電位方向に掃引し、掃引に対する電流変化を検出することによりヒドラジン濃度を測定する（濃度測定工程）。【選択図】図２