Abstract: A method for determining the concentration of a substrate in a sample solution using an electrode system comprising a working electrode and a counter electrode, both being formed on an electrically insulating base plate, and a reaction layer which contains at least an oxidoreductase and an electron mediator and is formed on the electrode system to electrochemically measure a reduced amount of the electron mediator resulting from enzyme reaction in the reaction layer, wherein a third electrode is formed as an interfering substance detecting electrode somewhere apart from the reaction layer to detect supply of the sample solution on the basis of an electrical change between the counter electrode and the third electrode. A current flowing between the counter electrode and the third electrode is measured which is taken as a positive error.

Abstract: The present disclosure relates to a method for determining cholesterol in low density lipoprotein comprising the steps of (a) measuring total cholesterol level in a sample containing at least high density lipoprotein, low density lipoprotein, very low density lipoprotein and chylomicron, and (b) measuring cholesterol levels in the high density lipoprotein, very low density lipoprotein and chylomicron in the sample, wherein the cholesterol level in the low density lipoprotein is determined by subtracting a value obtained in the step (b) from a value obtained in the step (a). The present invention enables concurrent determination of cholesterol level in low density lipoprotein and total cholesterol level, facilitating acquisition of two types of biological information at a time.

Abstract: The present invention provides a sensor that electrochemically determines cholesterol in low density lipoprotein by only one feed of a sample. The sensor has: an electrode system that is mounted on an electrically insulating base plate and includes at least a working electrode and a counter electrode; an enzyme layer formed on the base plate with the electrode system; and a reagent layer that is arranged before the enzyme layer in a sample solution supply path to the electrode system. The enzyme layer includes at least an oxidoreductase and an electron mediator. The reagent layer includes a reagent that depresses reactivity of cholesterol in lipoproteins other than the low density lipoprotein with the oxidoreductase, for example, a reagent that attaches to lipoproteins other than the low density lipoprotein to form a water-soluble complex.

Abstract: A method for determining the concentration of a substrate in a sample solution using an electrode system comprising a working electrode, a counter electrode, and a reaction layer which contains at least an oxidoreductase and an electron mediator and is formed on the electrode system to electrochemically measure a reduced amount of the electron mediator resulting from enzyme reaction in the reaction layer, wherein a third electrode is formed as an interfering substance detecting electrode. A current flowing between the counter electrode and the third electrode is measured which is taken as a positive error. Subsequently, voltage application between the counter electrode and the third electrode is released and a voltage for oxidizing the reduced form electron mediator is applied between the working electrode and the counter electrode to measure a current flowing between the two electrodes.

Abstract: A biosensor includes: an insulating substrate; an electrode system formed on the insulating substrate which has a working electrode and a counter electrode; and a reaction layer formed on the insulating substrate which contains an oxidoreductase and an electron acceptor. The electron acceptor is ferricinium ion derived from ferrocene electrolyte.

Abstract: The present invention provides a biosensor which enables prompt quantification by facilitating introduction of a sample solution even when the amount of the sample solution is small and improving dissolution of reagents. The biosensor comprises an insulating base plate; an electrode system including at least a measuring electrode and a counter electrode formed on the base plate; a cover member integrated into the base plate to form a sample solution supply pathway for supplying a sample solution to the electrode system between the cover member and the base plate; a reaction reagent system including at least an electron mediator and an oxidoreductase; and a carrier supporting at least the electron mediator or the oxidoreductase of the reaction reagent system, wherein the carrier is partially or wholly disposed outside the sample solution supply pathway.

Abstract: The present invention provides a sample solution treating instrument facilitating rapid and simplified adjustment of the condition of a sample solution proper for analysis with a biosensor before supply to the biosensor. The sample solution treating instrument in accordance with the present invention comprises control means, such as a catalyst or an adsorbent, for example, which can remove any interfering substance for adjusting the sample solution proper for measurement with a biosensor.

Abstract: The present invention provides a biosensor that has a reaction reagent system easily dissolved even in a sample solution containing a high concentration of a substrate and ensures rapid and highly accurate measurement. The method of forming a target reaction layer according to the present invention dissolves a material constituting the target reaction layer in a solvent of a sublimable substance to prepare a solution, applies the solution in a desired area to form the target reaction layer, freezes the applied solution, and sublimates the solvent included in a solid matter of the frozen solution under reduced pressure for removal. The resultant reaction layer has a large surface area and is easily dissolved in the sample solution to enable rapid measurement.

Abstract: A method using a biosensor is disclosed which facilitates high accuracy quantitation of a substrate by best eliminating adverse effects of red blood cell existing in blood together with the substrate. The biosensor comprises an electrode system including a working electrode and a counter electrode formed on an electrically insulating base plate, and a reaction layer containing at least an oxidoreductase and an electron acceptor, wherein the electron acceptor is a sodium salt.

Abstract: The present invention provides a biosensor having a high current response sensitivity, a low blank response and a high storage stability. This sensor comprises an electrode system including a working electrode and a counter electrode, for forming an electrochemical measurement system by coming in contact with a supplied solution; an insulating supporting member for supporting the electrode system; a first reagent layer formed on the working electrode; and a second reagent layer formed on the counter electrode, wherein the first reagent layer does not contain an enzyme, but it contains at least an electron mediator, and the second reagent layer does not contain an electron mediator, but it contains at least an enzyme.

Abstract: The present invention provides a biosensor having a favorable response characteristic up to a high concentration range, a low blank response and a high storage stability. This sensor comprises an electrode system including a working electrode and a counter electrode, for forming an electrochemical measurement system by coming in contact with a supplied solution; an electrically insulating supporting member for supporting the electrode system; a first reagent layer formed on the working electrode; and a second reagent layer formed on the counter electrode, wherein the first reagent layer comprises an enzyme as the main component, and the second reagent layer comprises an electron mediator as the main component.

Abstract: The invention provides a method for quantitative measurement of a substrate with high accuracy by electrochemically oxidizing an electron mediator which has been reduced by enzyme reaction thereby determining the substrate concentration based on a current flowing during electrochemical oxidation from which adverse effects of an easy-to-oxidize substance on the oxidation process have been minimized. The quantitating method in accordance with the present invention comprises a first step for causing a substrate contained in a sample to react with a specific oxidoreductase to the substrate in the presence of an electron mediator in oxidized state, and a second step for electrochemically reducing the electron mediator in oxidized state which remains non-reduced by the enzyme reaction in the first step, thereby obtaining a current flowing during electrochemical reduction.

Abstract: A cholesterol sensor for quantitative determination of cholesterol is provided containing an electrode system and a reaction reagent system. The electrode system contains a measuring electrode such as a carbon electrode and a counter electrode, and the reaction reagent system contains cholesterol dehydrogenase, nicotinamide adenine dinucleotide and an oxidized electron mediator. Electron mediators include ferricyanide, 1,2-naphthoquinone-4-sulfonate, 2,6-dichlorophenol indophenol, dimethylbenzoquinone, 1-methoxy-5-methylphenazinium sulfate, methylene blue, gallocyanine, thionine, phenazine methosulfate and Meldola's blue. Diaphorase, cholesterol esterase and a surfactant may also be present. The electrode system is on an insulating base plate, and the base plate has a covering member containing a groove that is a sample supplying channel which extends from an end of the base plate to the electrode system.

Abstract: A highly reliable biosensor is provided which is reduced in influences of any interfering substance or preexisting oxygen in a sample solution. The biosensor comprises an electrode system including a working electrode, a counter electrode and a third electrode also usable as an interfering substance detecting electrode, a reagent layer containing at least an oxidoreductase and an electron mediator, and an electrically insulating base plate for supporting the electrode system and the reagent layer, wherein the third electrode is arranged at an opposing position to that of at least one of the working electrode and the counter electrode and the reagent layer is arranged at a predetermined position apart from the third electrode.

Abstract: A cholesterol sensor facilitating rapid measurement of serum cholesterol levels is disclosed. The sensor comprises an electrode system composed of at least a measuring electrode and a counter electrode and disposed on an electrically insulating base plate and a reaction layer formed on or in the vicinity of the electrode system. The reaction layer contains cholesterol esterase for catalyzing the conversion of cholesterol ester into cholesterol, cholesterol oxidase and a surfactant.

Abstract: Disclosed is an electrode probe and a body fluid examination equipment enabling examination of a trace amount of body fluid. The electrode probe comprises an insulating needle member, a working electrode lead disposed in the needle member, a working electrode whose lead is protruding outside from the needle member, a counter electrode disposed on the surface of the needle member, a lead connected to the counter electrode, and a reagent layer disposed in contact with or in the vicinity of the working and counter electrodes of the electrode system. When a trace amount of body fluid leaking on the skin surface is brought into contact with the reagent layer, the reagent layer dissolves which results in electron transfer whereby information about the concentration of analyte in the body fluid can be obtained from the electrode system.

Abstract: Disclosed is a biosensor facilitating high accuracy quantification of a specific component in a sample solution with no adverse influence of solid substances. The biosensor comprises an electrically insulating base plate, an electrode system comprising a working electrode and a counter electrode formed on the base plate, a reaction layer containing at least one enzyme disposed on the electrode system, and an anionic filter formed on the reaction layer for inhibiting permeation of solid components.

Abstract: A cholesterol sensor is disclosed which comprises an electrode system having a measuring electrode and a counter electrode formed on an electrically insulating base plate, an electrode coating layer for covering the electrode system and a reaction reagent layer formed on or in the vicinity of the electrode coating layer, wherein the reaction reagent layer comprises at least an enzyme for catalyzing cholesterol oxidation, an enzyme having a cholesterol ester hydrolyzing activity and a surfactant, the electrode coating layer comprises at least one selected from the group consisting of water-soluble cellulose derivatives and saccharides and is contained at such a concentration that imparts sufficient viscosity to a sample solution for enabling it to hinder invasion of said surfactant into said electrode system when said electrode coating layer is dissolved in said sample solution supplied to said sensor.

Abstract: A biosensor for rapid quantification of a specific component contained in various biological samples with high accuracy has an electrically insulating base, an electrode system including a working electrode and a counter electrode formed on one face of the insulating base, and a reaction layer formed on the insulating base in close contact with the electrode system. The reaction layer contains at least a hydrophilic polymer, a buffer and an enzyme which is separated from the buffer.

Abstract: .[.There is disclosed an aqueous dispersed solution as a standard solution for determining lipid levels, having a dispersion form and a particle size, which are similar to those of serum lipids. A lipid-dispersed solution is obtained by evaporating an organic solvent from a mixture prepared by adding cholesterol, a phospholipid, a bile acid or bile acid salt, and a neutral lipid and/or a cholesterol ester in the organic solvent, swelling the resultant thin-film like mixture with water or buffer heated at a temperature higher than a phase transition temperature of the lecithin, and then dispersing the solution by a physical shear force. There can be easily obtained a solution having a cholesterol concentration of about less than 1,000 mg/dl, which is extremely stable and can be stored for a long period of time..]. .Iadd.There is disclosed an aqueous dispersed solution as a standard solution for determining lipid levels, having a dispersion form and a particle size, which are similar to those of serum lipids.