Abstract: Disclosed are an immunoassay method which can measure an antigen with high sensitivity and accuracy; and a reagent therefor. In the immunoassay method, an antigen-antibody reaction and/or a measurement is(are) carried out in the presence of a polycarboxylic acid type surfactant. The immunoassay reagent for use in the method is characterized by comprising the polycarboxylic acid type surfactant. By employing such a simple means that the polycarboxylic acid type surfactant is allowed to be present in the reaction and/or measurement system, non-specific reactions can be suppressed effectively even in a highly sensitive immunoassay, and an antigen can be measured accurately and specificity can be improved in the immunoassay.

Abstract: Object: To provide a test reagent for the analyte in a test sample, utilizing the level of agglutination of a particle suspension which suspend insoluble carrier particles carrying a substance for capturing the analyte as an indicator, which reagent does not undergo self-agglutination during storage, and which non-specific agglutination rarely occurs during measurement, as well as to provide a method for the analyte to be measured in a test sample. Means for Solution: The test reagent for the analyte comprises at least a Solution A which is a buffer solution having an electric conductivity of not less than 30 ms/cm; and a Solution B having an electric conductivity of not more than 6.5 ms/cm, the Solution B being a particle suspension which suspends particles which are insoluble carrier particles carrying a substance for capturing the analyte.

Abstract: [Problems] An object of the present invention is to provide a novel method which can expand the measurement range in an immunoassay method. [Means for Solution] The immunoassay method according to the present invention comprises allowing a polyoxyethylene alkyl ether sulfate and a polyoxyethylene sorbitan fatty acid ester to coexist in a reaction system. [Effects] According to the method of the present invention, variation (standard deviation) in blank measurement values in particular can be reduced, so that measurement values are stabilized. By this, a significant difference can be obtained in measurement values even in a low-concentration range where conventional immunoassay methods have difficulty in performing measurements; therefore, the measurement accuracy in such low-concentration range can be improved.

Abstract: Disclosed are an immunoassay method which can measure an antigen with high sensitivity and accuracy; and a reagent therefor. In the immunoassay method, an antigen-antibody reaction and/or a measurement is(are) carried out in the presence of a polycarboxylic acid type surfactant. The immunoassay reagent for use in the method is characterized by comprising the polycarboxylic acid type surfactant. By employing such a simple means that the polycarboxylic acid type surfactant is allowed to be present in the reaction and/or measurement system, non-specific reactions can be suppressed effectively even in a highly sensitive immunoassay, and an antigen can be measured accurately and specificity can be improved in the immunoassay.

Abstract: Provided is a means for improving measurement accuracy in an immunoassay using a dry plastic cell. A method for reducing adsorption of bubbles onto a cell side surface in an immunoassay, the method including carrying out a reaction and/or measurement in a presence of a surfactant, wherein the immunoassay comprises carrying out an antigen-antibody reaction in a dry plastic cell using an immunoassay reagent which immunologically reacts with a substance to be measured in a sample and carrying out an optical measurement of a resultant reacted product.

Abstract: [Problems] An object of the present invention is to provide a novel method which can expand the measurement range in an immunoassay method. [Means for Solution] The immunoassay method according to the present invention comprises allowing a polyoxyethylene alkyl ether sulfate and a polyoxyethylene sorbitan fatty acid ester to coexist in a reaction system. [Effects] According to the method of the present invention, variation (standard deviation) in blank measurement values in particular can be reduced, so that measurement values are stabilized. By this, a significant difference can be obtained in measurement values even in a low-concentration range where conventional immunoassay methods have difficulty in performing measurements; therefore, the measurement accuracy in such low-concentration range can be improved.

Abstract: Object: To provide a test reagent for the analyte in a test sample, utilizing the level of agglutination of a particle suspension which suspend insoluble carrier particles carrying a substance for capturing the analyte as an indicator, which reagent does not undergo self-agglutination during storage, and which non-specific agglutination rarely occurs during measurement, as well as to provide a method for the analyte to be measured in a test sample. Means for Solution: The test reagent for the analyte comprises at least a Solution A which is a buffer solution having an electric conductivity of not less than 30 ms/cm; and a Solution B having an electric conductivity of not more than 6.5 ms/cm, the Solution B being a particle suspension which suspends particles which are insoluble carrier particles carrying a substance for capturing the analyte.