Theory and Practise of Rapid Flow-Through Analysis Based on Optode Detection and Its Application to pH Measurement as a Model Case

Rapid flow-through analysis (RFA) based on optode (optical chemical sensor) detection is proposed, and its performance is discussed using the RFA system equipped with a pH-sensitive optode as a model case. To demonstrate and understand the usefulness of the RFA system, long-lifetime pH-sensitive optodes were prepared using a hydrophilic poly(hydroxyethyl methacrylate) (poly-HEMA) membrane covalently immobilized with a dye containing an amino group such as Congo Red or Nile Blue. The response equation for the optode with the RFA system was proposed, and satisfactory estimation for rapid pH analysis was obtained. The proposed RFA can stand as an advanced method for conventional flow injection analysis.