Abstract: A stool sample evaluation flotation agent comprising at least 0.01 mol/kg of a first compound which, in a dissolved state, releases anions by a buffer effect to generate and stabilize a neutral pH environment having a pH between 6.0 and 8.0. A method of stool sample examination involving separating endoparasites from a stool sample, the method comprising mixing the stool sample with a flotation agent comprising at least 0.01 mol/kg of a first compound which, in a dissolved state, releases anions by a buffer effect to generate and stabilize a neutral pH environment having a pH between 6.0 and 8.

Abstract: A fixative for the preservation of organic tissue and cell aggregates, comprising a hydrophilic denaturant for structural change of the molecules of the organic tissue, a lipophobic solvent, in which said denaturant is dissolved, and an amphiphilic infiltration agent which is dissolved in the solvent for dissolving fats on the surface of the biological tissue in order to accelerate a penetration of the denaturant into the biological tissue.

Abstract: A fixative for fixing biological materials contains a depot agent, preferably a polyamine and especially hexamethylenetetramine, which reacts chemically with positively charged ions, especially H+ from an acid, while forming a fixative, where the fixative is an aldehyde and especially formaldehyde, which in turn reacts chemically with the biological material to be fixed in order to fix it and is consumed in doing so. By adjusting the pH of a solution containing the depot agent, a chemical equilibrium reaction occurs between the depot agent, fixative and biological material, so that just as much fixative is continuously formed as can be immediately consumed by the biological material. With that, the fixative, and especially the hazardous formaldehyde, cannot escape. Thus, an externally formaldehyde-free fixative that at the same time has the excellent fixative properties of formaldehyde is created.

Abstract: A fixative for fixing biological materials contains a depot agent, preferably a polyamine and especially hexamethylenetetramine, which reacts chemically with positively charged ions, especially H+ from an acid, while forming a fixative, where the fixative is an aldehyde and especially formaldehyde, which in turn reacts chemically with the biological material to be fixed in order to fix it and is consumed in doing so. By adjusting the pH of a solution containing the depot agent, a chemical equilibrium reaction occurs between the depot agent, fixative and biological material, so that just as much fixative is continuously formed as can be immediately consumed by the biological material. With that, the fixative, and especially the hazardous formaldehyde, cannot escape. Thus, an externally formaldehyde-free fixative that at the same time has the excellent fixative properties of formaldehyde is created.