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: Devices and methods are provided for determining specific gravity or osmolality of liquids. The preferred devices comprise a carrier matrix incorporated with microcapsules having osmotically fragile, semipermeable polymeric membrane walls encapsulating therein a solute and a coloring substance. In use, the test device is contacted with the liquid to be tested, and color change on the carrier matrix is observed as a measure of the specific gravity or osmolality of the liquid.