Abstract: This invention provides a reference electrode that can be downsized and stable in voltage. The reference electrode in accordance with this invention is a reference electrode that does not require an internal aqueous solution such as a KCl aqueous solution and comprises a metal body, a slightly soluble salt film that comprises a slightly soluble salt of the metal body and that coats the metal body and a hydrophobic ionic liquid that is arranged to make contact with both the slightly soluble salt film and a sample to be measured.

Abstract: The present claimed invention is to provide a method for measuring a protein that enables to detect the protein with high accuracy and high sensitivity through an electrochemical method at a high speed with a simple operation using a simple device. With the method, a working electrode 5 and a counter electrode 4 are made to contact with a sample solution 1 containing the protein as being an object to be measured, and a voltage is impressed between the working electrode 5 and the counter electrode 4 so that a current value at the voltage can be measured and the protein can be electrochemically analyzed.

Abstract: The present claimed invention is to provide a reference electrode wherein variations of a potential difference at a liquid junction can be removed almost completely, contamination of a sample solution can be minimized, a frequency to supply and replace an internal solution is lessened, the liquid junction is prevented from being clogged, high durability for a long term can be maintained and a measurement with high accuracy can be conducted, and comprises an internal electrode 21, an internal solution 22 that makes a contact with the internal electrode 21 and a liquid junction 23 that continues into the internal solution 22, wherein the liquid junction 23 is made by the use of a gelled hydrophobic ionic liquid.

Abstract: This invention provides a reference electrode (3) that can be downsized and stable in voltage. The reference electrode (3) in accordance with this invention is a reference electrode (3) that does not require an internal aqueous solution such as a KCl aqueous solution and comprises a metal body (31), a slightly soluble salt film (32) that comprises a slightly soluble salt of the metal body (31) and that coats the metal body (31) and a hydrophobic ionic liquid (33) that is arranged to make contact with both the slightly soluble salt film (32) and a sample to be measured.

Abstract: The present claimed invention is to provide a reference electrode wherein variations of a potential difference at a liquid junction can be removed almost completely, contamination of a sample solution can be minimized, a frequency to supply and replace an internal solution is lessened, the liquid junction is prevented from being clogged, high durability for a long term can be maintained and a measurement with high accuracy can be conducted, and comprises an internal electrode 21, an internal solution 22 that makes a contact with the internal electrode 21 and a liquid junction 23 that continues into the internal solution 22, wherein the liquid junction 23 is made by the use of a gelled hydrophobic ionic liquid.