The present invention announces a method for extending the storage life of a test reagent for quantification of ionic components in samples by using an anion sensor. The purpose of the present invention is to provide an anion sensor, wherein the storage life of the anion sensor itself may be extended, to thereby extend the storage life of the anion sensor beyond that of conventional anion sensors. According to the present invention, through adjustment of the pH of the internal solution (internal gel liquid), it is possible to provide an anion sensor that maintains consistent performance, and has longer storage life.
1. An anion sensor comprising:
an ion electrode membrane where an anion exchange membrane containing a cation compound is coated with a material containing an amine compound which has an ionization group of a predetermined pKa;
a container which defines a space which accommodates an internal solution, a flow channel configured to receive a sample therein disposed in the container, wherein the ion electrode membrane is disposed in the container with a portion or an entirety of a first surface of the ion electrode membrane in contact with the flow channel and a portion or an entirety of a second surface of the ion electrode membrane in contact with the internal solution; and
an electrode disposed in contact with the internal solution,
wherein the ion electrode membrane, the internal solution, and the electrode are disposed in the container,
wherein the internal solution contains NaCl or KCl and a pH buffer solution,
wherein the pH buffer solution is an ammonium chloride buffer solution,
wherein pH of the internal solution is adjusted so as to be equal to or greater than the pKa of the amine compound having the ionization group, and
wherein pH of the adjusted internal solution has a value of pH 11.
2. The anion sensor according to claim 1 , wherein a concentration of anions in the internal solution is equal to or greater than 1 mmol/L.