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Paraformaldehyde can be depolymerized to formaldehyde gas by dry heating [2] and to formaldehyde solution by water in the presence of a base, an acid or heat. The high purity formaldehyde solutions obtained in this way are used as a fixative for microscopy and histology. The resulting formaldehyde gas from dry heating paraformaldehyde is flammable.
A saturated water solution, of about 40% formaldehyde by volume or 37% by mass, is called "100% formalin". A small amount of stabilizer, such as methanol, is usually added to suppress oxidation and polymerization. A typical commercial-grade formalin may contain 10–12% methanol in addition to various metallic impurities.
The pulping of wheat straw with 40% mixtures of acetone or ethanol with water requires 60 minutes at 180 °C to give good pulp properties. [4] Organic solvents are almost always used as a mixture with water for process considerations such as reducing the vapour pressure and lowering the pH in order to also solubilise hemicellulose.
Water Conditioner. These are designed to balance the "hardness" of water (the presence of other trace chemicals that change the water's pH or neutrality) and to help reduce the deceased's acidity, a by-product of decomposition, as formaldehyde works best in an alkaline environment. Additionally, water conditioners may be used to help inactivate ...
This page contains tables of azeotrope data for various binary and ternary mixtures of solvents. The data include the composition of a mixture by weight (in binary azeotropes, when only one fraction is given, it is the fraction of the second component), the boiling point (b.p.) of a component, the boiling point of a mixture, and the specific gravity of the mixture.
A prominent example is the bacterial mesosome, which was thought to be an organelle in gram-positive bacteria in the 1970s, but was later shown by new techniques developed for electron microscopy to be simply an artifact of chemical fixation. [2] [3] Standardization of fixation and other tissue processing procedures takes this introduction of ...
2.0 g paraformaldehyde; 25 ml distilled water; 1M sodium hydroxide 2 to 4 drops; 50% glutaraldehyde 5.0 ml; 0.2M cacodylate buffer, pH 7.4, 20.0 ml; Mix the paraformaldehyde with 25 ml of distilled water in a 125 ml Erlenmeyer flask. Heat to 60 °C on a stir plate. When moisture forms on the sides of flask, add sodium hydroxide and stir until ...
Zenker's fixative is a rapid-acting fixative for animal tissues. It is employed to prepare specimens of animal or vegetable tissues for microscopic study. It provides excellent fixation of nuclear chromatin, connective tissue fibers and some cytoplasmic features, but does not preserve delicate cytoplasmic organelles such as mitochondria.