| abstract |
A reference solution for measuring an ionic activity which is utilized at the time of measuring the activity of a particular ion in an aqueous solution by the differential method using ion-selective electrodes, which is characterized by containing the compound having the general formula (I), (II) or (III) and an electrolyte. <IMAGE> (I) wherein R1, R2, R3 and R4 represent hydrogen atom or a lower alkyl group, respectively, and at least, one or R3 and R4 is a lower alkyl group, and X represents chlorine atom or bromine atom, <IMAGE> wherein R5 represents hydrogen atom or a lower alkyl group and A represents a hydrogen atom or a halogen atom, and <IMAGE> (III) wherein R6 represents a hydrogne atom or a lower alkyl group. The reference solution of the invention may be preserved for a long period at room temperature without putrifaction, and the compound (I), (II) or (III) in the reference solution does not or scarcely influence upon the potential difference generated in the ion-selective electrode. |