Chemical substance measuring apparatus

A chemical substance measuring apparatus for measuring the quantities of chemical substances contained in a solution to be assayed, said chemical substance measuring apparatus comprising:

• a tubular body having at least two independent cavities;
• a chemical-substance sensitive sensor having;
• a potentiometric electrode housed in one of said cavities and capable of responding selectively to specific chemical substances, said electrode having a chemical-substance measuring zone projecting outwardly from one end of the tubular body,
• a lead wire connected at one end thereof to said electrode and extending on the other end side thereof along said cavity, with other end of said lead wire being connected to a connector at an opening of said tubular body at the other end thereof;
• and
• an electrical insulating resin filled in said electrode at least at a lead wire junction thereof for stopping the cavity;
• and
• a liquid-junction type reference electrode including a porous thread member housed in the front end portion of the other cavity and having a pore capacity of 0.2 cc/g or more and having at least a hydrophilic surface
• a silver-silver chloride wire housed in said cavity such that one end of said wire is in contact with said thread member and wherein said wire extends along the cavity and is connected to a connector at an opening of the other end of the cavity,
• an electrical insulating resin filled in said cavity at least at the front end portion thereof, for fixing both the silver-silver chloride wire and the thread member by contact therewith and further for additionally stopping said cavity, and
• an internal solution retained by suction in the porous thread member.