Abstract: A composition, device and method for determining the presence of a reducing agent, such as ascorbic acid, in a test sample are disclosed. The composition comprises certain thiazine and oxazine compounds which, in their oxidized state, are colored, but which become colorless when reduced by a reducing agent. The device comprises a carrier matrix incorporated with the composition, and the method comprises contacting a test sample with the composition device and observing any detectable response such as a color change.

Abstract: A method and device for determining the specific gravity or osmolality of a liquid containing a nonionic, ionizable solute are disclosed. The method comprises contacting the liquid with an ionizing agent, thus converting the solute to ionized species in the liquid, and contacting the liquid with test means capable of producing a detectable response, such as a color response, dependent upon the specific gravity or osmolality of the ionized liquid. The composition comprises an ionizing agent capable, upon contact with the liquid, of ionizing the solute therein, and a test means capable, upon contacting the liquid containing the solute in ionized form, of producing a detectable response which is a function of the specific gravity or osmolality of the liquid. The device comprises a carrier matrix incorporated with the test means and the ionizing agent.

Abstract: A test composition is disclosed which is useful in determining the presence of a peroxidatively active substance, such as hemoglobin, in a test sample. The composition comprises an organic hydroperoxide, an indicator capable of producing a detectable response in the presence of a peroxide, and a diluent having the structure ##STR1## IN WHICH R.sub.1 and R.sub.2, same or different, are hydrogen, alkyl or alkoxy having 1 to about 6 carbon atoms, or aryl. The method comprises preparing the test composition and incorporating it with a carrier matrix.

Abstract: A test device, test composition, and method are disclosed for determining the presence of a component in a sample. The device comprises a carrier matrix incorporated with a reactant system which produces a detectable response upon contact with the sample component. After a predetermined time interval elapses, the production of the detectable response is terminated by an inhibitor system also incorporated with the matrix. The test composition comprises the reactant and inhibitor systems. The method of use comprises contacting the test device with a test sample suspected of containing the component, permitting a predetermined time to elapse after contacting, and observing any detectable response produced.