Abstract: A membrane structure useful in filtration and diagnostic tests includes a microporous membrane formed from a biologically inert material, such as a polyamide, and has a coating comprising one or more water-soluble proteins or carbohydrates. None of the proteins and carbohydrates in the coating has a pI greater than about 5. The membrane structure is prepared by contacting the microporous membrane with the appropriate protein or carbohydrate in an amount sufficient to provide a coating over the entire membrane surface without substantially diminishing the porosity of the membrane. The membrane structure is useful in various diagnostic test procedures, such as agglutination assays.

Abstract: An agglutination reagent is prepared by covalently attaching an immunoreactive species to polymeric particles through reactive groups in the species. After attachment, the species is chemically modified with an acylating, alkylating or sulfonylating agent thereby modifying primary or secondary amino groups. The reagent can be used in agglutination assays for a number of analytes, inclusing Streptococcus A antigen, human retroviruses or antibodies, human chorionic gonadotropin and other antibodies or antigens.

Abstract: A reagent useful in the determination of an immunoreactive species comprises water-insoluble particles having tracer molecules associated therewith. Bound to the outer surface of the particles are: (i) receptor molecules which are reactive with the species, and (ii) molecules of a protein having a pI less than about 6, and which protein is not reactive with either the species or the receptor molecules. The weight ratio of the receptor molecules to the low pI protein molecules is from about 100:1 to about 1:10. This reagent is useful in agglutination and other immunological reactions. A method of preparing the reagent includes providing a suspension of the particles and contacting them with the receptor molecules and low pI protein so as to attach both to the particles. The protein is present in the suspension in an amount such that substantially all of it is attached to the particles.

Abstract: A dry multilayer analytical element for determination of total ionic iron is disclosed. The element includes a dye which complexes with Fe.sup.+2. The dye has the structure ##STR1## R.sup.1 represents an electron donating group; or R.sup.1, together with the carbon to which it is attached, represents sufficient atoms to form a cyclic electron donating group fused to the phenyl group to which R.sup.1 is attached;R.sup.2 represents an electron withdrawing group; andR.sup.3 represents H, Cl, F, Br or OR.sup.4 wherein R.sup.4 represents a hydrocarbon having from 1 to 20 carbon atoms.

Abstract: There is disclosed a method for quantitatively determining protein, comprising the steps of:(a) providing a sample of the protein in an aqueous medium;(b) providing an aqueous medium having a pH in excess of 12 and comprising(i) a cupric salt and a pyridyl-azo dye; or(ii) a preformed cupric-pyridylazo dye complex;(c) combining the aqueous mediums of a) and b) thereby providing a color having an intensity which is inversely proportional to the amount of unreacted dye present in the combined mediums; and(d) determining the quantity of protein present in the sample colorimetrically.The method can be used with a multilayer dry analytical element.

Abstract: Photographic elements and diffusion transfer assemblages employing a nondiffusible compound capable of releasing at least one diffusible cyan dye moiety, and having the formula: ##STR1## wherein: (a) J represents SO.sub.2 or CO,(b) R represents a substituted or unsubstituted alkyl group of from 1 to about 10 carbon atoms or a substituted or unsubstituted aryl group of from 6 to about 12 carbon atoms,(c) G represents a hydroxy group, a salt thereof, or a hydrolyzable precursor thereof,(d) CAR represents a ballasted carrier moiety, and(e) D.sup.1, D.sup.2, and D.sup.3 each independently represents H or one or more electron-withdrawing groups selected from --SO.sub.2 Y.sup.1, --CONY.sup.1 Y.sup.2, --Cl, --COY.sup.1, --C.tbd.N and --SO.sub.2 NY.sup.1 Y.sup.2, where Y.sup.1 and Y.sup.2 each independently represents hydrogen, a substituted or unsubstituted alkyl group of from 1 to about 10 carbon atoms or a substituted or unsubstituted aryl group of from 6 to about 12 carbon atoms.