Abstract: The present invention provides a high performance glucose sensor which can demonstrate high stability against preservation and produces only a low blank value. The glucose sensor comprises an electrically insulating base plate, an electrode system formed on the base plate, and a reaction layer which is formed in contact with or in the vicinity of the electrode system and contains at least a glucose dehydrogenase whose coenzyme is pyrrolo-quinoline quinone, the reaction layer further containing an additive such as phthalic acid.

Abstract: Measurement of the concentration of a specific component in a test liquid is made more efficient by obtaining a mixed liquid of the test liquid and a reagent liquid without having to perform a stirring operation. A mixed liquid comprising the test liquid and the reagent liquid is obtained by injecting the reagent liquid into the test liquid with stirring caused by the injection; and with the test liquid being irradiated with light, at least a first optical characteristic of the test liquid before the injection of the reagent liquid and a second optical characteristic of the test liquid after the injection of the reagent liquid are measured to measure the concentration of the specific component in the test liquid from the first optical characteristic and the second optical characteristic.

Abstract: A biosensor that enables rapid and simple quantitation of a substrate with high accuracy and demonstrates an excellent preservation characteristic by best retaining enzyme activity is disclosed. The biosensor comprises an electrically insulating base plate, an electrode system including at least a working electrode and a counter electrode formed on the base plate, and a reaction layer containing at least an enzyme and a sugar. The reaction layer may be formed on the electrode system. The enzyme may be selected from glucose oxidase, glucose dehydrogenase, and fructose dehydrogenase. The sugar is trehalose, sucrose, glycerol, mannitol, and ribose. If the enzyme selected is glucose dehydrogenase whose coenzyme is pyrrolo-quinoline quinone, the use of trehalose is preferable.

Abstract: The immunoassay method of this invention measures the content of a subject substance in a sample. The method includes the steps of: (a) preparing a mixed solution by mixing the sample and an antibody solution including a first monoclonal antibody and a second monoclonal antibody capable of specifically binding to the subject substance; and (b) measuring an optical property of the mixed solution. The first monoclonal antibody is capable of binding to a first epitope of the subject substance, and the second monoclonal antibody is capable of binding to a second epitope of the subject substance different from the first epitope. Each of the first and second epitopes exists singly in the subject substance.

Abstract: It is intended to provide an antibody specific to HbA1c, antibody-producing cells capable of supplying the antibody in a stable state in the future, and a method of constructing the antibody-producing cells without any probability factors, and a method which comprises fusing mouse spleen cells, which have been sensitized with an immunogen composed of a compound containing the following structural formula (I) and a binding protein, with a myeloma-origin cell line, obtaining monoclonal antibody-producing cells by cloning, and then purifying and acquiring the monoclonal antibody produced by these cells into the culture supernatant.

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 preparing a cocaine-protein conjugate easily by using a cocaine derivative having a methoxy carbonyl group and benzoyl group. This conjugate is useful for the detection of cocaine or cocaine derivatives.

Abstract: A method for preparing a cocaine-protein conjugate easily by using a cocaine derivative having a methoxy carbonyl group and benzoyl group. This conjugate is useful for the detection of cocaine or cocaine derivatives. A monoclonal antibody, a monoclonal antibody producing cell line, and a method for producing the monoclonal antibody producing cell line by using the above cocaine-protein conjugate as an immunogen is also described.

Abstract: A labelling color of pentamethine, its intermediate and a method for preparing and using the same to detect methamphetamine with high sensitivity.The invention is exemplified by pentamethine of the following Formula (1): ##STR1## wherein R.sup.1, R.sup.2, R.sup.3 and R.sup.4 each are a C.sub.1-6 alkyl group, and X is an anion.A method for using the labelling color to detect methamphetamine. The method comprises preparing a solution of the labelling color and methamphetamine-antibody in a buffer, measuring its fluorescent intensity at 660 nm in a 600 nm excited state, adding methamphetamine in a buffer to the solution, measuring its fluorescent intensity similarly, and examining the change in fluorescent intensity between both solutions.

Abstract: A labelling color which includes a pentamethine of the following formula (1): ##STR1## wherein R.sup.1, R.sup.2, R.sup.3 and R.sup.4 each are a C.sub.1-6 alkyl group, and X is an anion.