Method and apparatus for obtaining an aliquot of a liquid in a gel medium

Abstract

There is disclosed a method and apparatus for obtaining a precise aliquot of a sample by diffusing the sample into a gel mass for a controlled period of time. The sample may comprise a liquid containing an unknown quantity of a diffusible, to-be-assayed, component or components. The method may further include reacting a component of the sample with an assay-reagent present in excess quantity above that needed for reaction, the reagent being disposed in the gel mass. The sample is placed in contact with a preselected surface area of the gel mass. The component of the sample is allowed to diffuse into the gel mass for a controlled period of time. Thereafter, the remainder of the sample containing the component is removed, and further diffusion of the component through the gel mass may proceed for a controlled period of time. This provides both a further dilution of the component and permits continuous reaction of the component with a reagent distributed throughout the gel mass. It is possible to measure the degree of reaction between the diffused component and the reagent in the gel mass. Alternatively, the method may involve obtaining an aliquot of a sample containing an unknown quantity of diffusible, to-be-assayed component as above, but without requiring further dilution via diffusion. Also, there may be no need for any assay-reagent and a property of the to-be-assayed component such as color, fluorescence, etc. may be measured directly in the gel mass. In another embodiment, the invention may be practiced so as to obtain a precise aliquot of a sample or of a reagent by diffusing them into a gel mass for a controlled period of time.