PROBLEM TO BE SOLVED: To provide a method and apparatus for measuring a pH of a solution without requiring correction on a zero level with wavelengths around 700 nm where absorbency is hardly indicated by an indicator.SOLUTION: The method for measuring a pH of a solution includes: a light emission step of emitting light beams of two wavelengths from one side within a measuring region of the solution in which the indicator is mixed a light receiving step of receiving the transmitted light beams and/or reflected light beams of the two wavelengths on the other side within the measuring region an absorbance computing step of computing absorbances based on the transmitted light beams and/or reflected light beams received in the light receiving step an absorbance ratio computing step of computing an absorbance ratio from the absorbances of the two wavelengths computed in the absorbance computing step and a pH value computing step of computing a pH value of the solution based on the absorbance ratio and a previously stored absorbance ratio-pH correspondence database. The method for measuring a pH of the solution is characterized by including a step of executing the light emission step and the light receiving step of the light beams of the two wavelengths while pulsating the solution in the measuring region.COPYRIGHT: (C)2012,JPO&INPIT【課題】指示薬による吸光性を殆ど示さない700nm付近の波長によるゼロレベルの補正の必要の無い溶液のpH測定方法、pH測定装置を提供する。【解決手段】指示薬を混合した溶液の計測領域内の一方側から2つの波長の光を照射する光照射ステップと、前記計測領域内の他方側で、前記照射された2つの波長の透過光及び/又は反射光を受光する光受光ステップと、前記光受光ステップにより受光された透過光及び/又は反射光に基づき吸光度を求める吸光度演算ステップと、前記吸光度演算ステップで演算された2つの波長の吸光度から吸光度比を求める吸光度比演算ステップと、前記吸光度比と予め格納された吸光度比-pH値対応データベースに基づいて前記溶液のpH値をpH値演算ステップと、を含む溶液pH計測方法であって、前記2つの波長の光照射ステップ及び光受光ステップを、前記計測領域の溶液を脈動させながら実行するステップとを含むことを特徴とする溶液のpH計測方法。【選択図】図1
