SUBSTANCE DETECTING METHOD

摘要

PROBLEM TO BE SOLVED: To stably detect a specified substance in solutions to be inspected by adding the specified substance in common to the solutions before measuring a plurality of solutions using a molecular film so that various characteristics non-related to presence/absence of the specified substance are substantially uniform. SOLUTION: In detecting a harmful substance in solutions to be inspected such as river water and a waste water from a plant, a conductivity increasing substance and a pH adjustment substance of appropriate quantity are added to each solution for pre-processing, and the conductivity and the pH value of each solution are thus substantially constant. To achieve the measurement by a probe having the molecular film, the information attributable to the variance of the conductivity and the pH value is canceled from the measurement value, and the measurement value dependent on the harmful substance can be extracted selectively. The harmful substance can be detected without any load in the operation. The conductivity and the pH value of the reference solution for measurement are not necessarily made to coincide with those of the solution to be inspected so long as the difference in electric potential can be grasped for each solution.