Abstract: An integral analytical element capable of use in the analysis of liquids, the element having at least two superposed layers including a spreading layer and a reagent layer, in fluid contact. Optionally, the element can be carried on a support material. The spreading layer, which can be an isotropically porous layer, spreads within itself at least a component of a liquid sample applied to the element, or a reaction product of such component, to obtain a uniform concentration of at least one such spread substance at the surface of the spreading layer which faces the reagent layer. The reagent layer, which is desirably uniformly permeable to at least one dissolved or dispersed component of the liquid sample or a reaction product of such a component, can include a matrix in which is distributed a material that can interact with, for example, an analyte or analyte reaction product to produce a detectable change in the element, such as one detectable by measurement of electromagnetic radiation.