Patent ID: 6767450
Filing Date: 2004-07-27
Classification: G01N

Abstract:
A composite ion selective electrode comprising a calcium ion selective electrode member and a hydrogen ion selective electrode member,in which the calcium ion selective electrode member comprises an electro-insulating support, a first pair of electrode units each which comprises a silver layer and a silver halide layer, the pair of electrodes being electrically separated from each other, an electrolyte layer, and a calcium ion selective membrane, and in which the hydrogen ion selective electrode member comprises an electro-insulating support, a second pair of electrode units each of which comprises a silver layer and a silver halide layer, and which are electrically separated from each other, an electrolyte layer, and a hydrogen ion selective membrane; (2) an electro-insulating member having two openings in which one opening is provided for introducing a sample liquid into one electrode of the calcium ion selective electrode of the calcium ion selective electrode member and one electrode of the hydrogen ion selective electrode member and another opening is provided for introducing a reference liquid into the composite electrode; (3) a pair of distributing members in which one distributing member distributes the introduced sample liquid to the ion selective membrane of each ion selective electrode member at a site corresponding to one electrode unit and in which another distributing member distributes the introduced reference liquid to the ion selective membrane of each ion selective electrode member at a site corresponding to another electrode unit; and (4) a bridge member which is provided on the electro-insulating member to bridge the two openings of the electro-insulating member so as to electrically connect the introduced sample liquid and the introduced reference liquid; which is characterized in that the calcium ion selective membrane has a thickness of 5 to 30 gym, and the hydrogen ion selective membrane contains tri-n-dodecylamine and trisethylhexyl trimellitate.