Abstract: Reagents have been prepared from water-insoluble polymeric particles to which are covalently attached avidin, biotin or an avidin or biotin derivative. The polymeric particles comprise a polymer on at least the outer surface which is derived from at least one ethylenically unsaturated monomer having a reactive activated 2-substituted ethylsulfonyl, vinylsulfonyl or active halogen atom. Covalent attachment of avidin, biotin or an avidin or biotin derivative is effected either directly or indirectly through these reactive groups. The resulting reagent is useful in analytical elements and various analytical methods including agglutination and sandwich assays. The immobilized avidin, biotin or derivative can be used to complex with the corresponding biotin or avidin molecule which may be conjugated to a compound of biological interest.

Abstract: A buffered aqueous composition is useful simultaneously as a wash solution and a dye-providing composition in specific binding assays involving enzyme-labeled specific binding reagents. The wash composition includes a dye-providing composition, a buffer and an organic solvent having a certain molecular weight and water-solubility. Another useful composition includes a particulate substrate having avidin attached thereto, and a peroxidase reducing agent. Either composition can be provided in a diagnostic test kit, and can be used to detect a specific binding ligand in assays.

Abstract: A test kit useful for the determination of an immunological ligand includes a labeled receptor for that ligand, a specific wash solution and a test device. The wash solution is buffered to a pH of from about 5 to about 9 and contains at least 0.01 weight percent of a compound having a dodecyl sulfate anion and an alkali metal or ammonium cation. One such compound is sodium dodecyl sulfate. The test device has several test wells, and in each well there is a microporous membrane. A receptor for the ligand of interest is immobilized in one test well. The kit is particularly useful for measuring human chorionic gonadotropin as an early indicator of pregnancy.

Abstract: A buffered aqueous composition is useful simultaneously as a wash solution and a dye-providing composition in specific binding assays involving enzyme-labeled specific binding reagents. The wash composition includes a dye-providing composition, a buffer and an organic solvent having a certain molecular weight and water-solubility. Another useful composition includes a particulate substrate having avidin attached thereto, and a peroxidase reducing agent. Either composition can be provided in a diagnostic test kit, and can be used to detect a specific binding ligand in assays.

Abstract: A dye-providing composition is useful in various diagnostic assays wherein a peroxidase-labeled specific binding species is used. This composition is substantially free of peroxidase and such labeled species, and comprises an imidazole leuco dye and 4'-hydroxyacetanilide present in an amount up to about 2.5 mmolar. This composition can be included as part of a diagnostic test kit.

Abstract: A dye-providing composition comprises a water-soluble or -dispersible polymer, such as a vinylpyrrolidone polymer, and an imidazole leuco dye capable of providing a dye in the presence of hydrogen peroxide and a peroxidative substance. The weight ratio of polymer to leuco dye is from about 10,000:1 to about 100:1. The dye-providing composition can be included with a peroxidase substrate in a diagnostic test kit. A method for the determination of a ligand can be carried out using a peroxidase labeled-receptor for the ligand and the dye-providing composition described above. The method is particularly useful for the determination of human chorionic gonadotropin (hCG).

Abstract: An aqueous wash solution is buffered to a pH of from about 5 to about 9 and contains at least about 0.01 weight percent of a compound comprising a dodecyl sulfate anion and an alkali metal or ammonium cation, such as sodium dodecyl sulfate. This wash solution is particularly useful in a method for the determination of an immunological ligand. Particularly, it is useful for washing the immunological complex formed between the ligand and a receptor molecule therefor. Unreacted materials can be readily separated from the complex by the washing, particularly if the separation is carried out using a filtration membrane in a test device. a test kit for ligand determination comprises the wash solution as well as one or more receptors for the ligand, at least one of which is labeled for detection. This kit is particularly useful for measuring human chorionic gonadotropin (hCG) as an early indicator of pregnancy.

Abstract: Certain phenols and anilines can be used as electron transfer agents to increase the rate of oxidation of leuco dyes by peroxidase. These phenols and anilines can react with hydrogen peroxide in the presence of peroxidase to provide intermediates which have higher oxidation potentials than the slowly oxidized substrates, e.g. the leuco dyes. These phenols and anilines can be used to advantage in both solution and dry assays of various analytes. They are particularly useful for the determination of an immunologically reactive ligand in an immunoassay.