Variants of the compositions of a series of placers for visually blister colorimetric determination of phosphate ion concentrations in a blister cell (tablet for tablets) containing a mixture of reagents are proposed. The placers allow quantitative determination of the phosphate concentration in various objects without preliminary preparation of reagent solutions. The application of reagents to the surface of silica gel makes it possible to isolate all reagents until a chemical reaction occurs. The composition and conditions of deposition of crystalline substances – reagents capable of providing a sufficiently high acidity with the addition of a few drops of a solution and an optimal reducing agent for blister conditions were optimized. The visual colorimetric reaction is carried out under conditions when the volume of the added solution is 0.1–0.2 ml.