Abstract: The present invention aims to simplify the structure and a fabrication method of an ion-selective electrode in an ion concentration measuring device that measures an anion, particularly a chloride ion, in a biological component. To this end, in a potential difference measuring unit, a quaternary ammonium salt derivative serving as a ligand for an anion is immobilized to the surface of a gold electrode by using as a linker an insulative molecule forming a self-assembled monolayer. The potential difference measuring unit measures an electromotive force generated with anion binding, as an interface potential change on the surface of the gold electrode. In order to reduce the influence of adsorption of impurities on the electrode surface, a high-molecular weight polymer is physically adsorbed on the gold electrode and thus used when a biological component is measured.

Abstract: The present invention provides a method of separating lipoproteins other than high density lipoproteins from a biological fluid. The method can quickly measure HDL cholesterol with a simple configuration and without the need of providing additional complicated devices. In this method, high density lipoproteins not generating any precipitate are fractionated from low density lipoproteins, very-low density lipoproteins, and chylomicrons generating precipitates. Then the precipitates are removed not by centrifugal separation based on the conventional technology, but by filtration using a filter to separate high density lipoproteins in blood serum. A hydrophilic cellulose-mixed ester is preferable as a material for the filter, and the pore diameter is 0.8 ?m or below. When the filtering method is employed, it is possible to eliminate the complicated operations required in the conventional centrifugal separation, and to shorten the time it takes for separation of the high density lipoproteins.

Abstract: A crown ether derivative that acts as cation capturing ligand and alkanethiol having a longer carbon chain than a linker are immobilized, coexisting together, on the surface of a gold electrode, by using as the linker an insulating molecule (e.g., alkanethiol) that forms self-assembled monolayers. Electromotive force produced in association with cation coordination is measured by a potentiometer through a change in interfacial potential on the surface of the gold electrode. Further, an insulated gate field effect transistor formed on the same substrate as the gold electrode is used as the potentiometer. Furthermore, a straight-chain polymer physically adsorbed on the gold electrode is used in order to reduce the influence of the adsorption of impurities on the surface of the electrode during biological sample measurement.