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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.
Cryofixation is a technique for fixation or stabilisation of biological materials as the first step in specimen preparation for the electron microscopy and cryo-electron microscopy. [1] Typical specimens for cryofixation include small samples of plant or animal tissue , cell suspensions of microorganisms or cultured cells , suspensions of ...
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 ...
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.
Typically, embalming fluid contains a mixture of formaldehyde, glutaraldehyde, methanol, and other solvents. The formaldehyde content generally ranges from 5–37% and the methanol content may range from 9–56%. In the United States alone, about 20 million liters (roughly 5.3 million gallons) of embalming fluid are used every year. [1]
Monomeric CH 2 O is a gas and is rarely encountered in the laboratory. Aqueous formaldehyde, unlike some other small aldehydes (which need specific conditions to oligomerize through aldol condensation) oligomerizes spontaneously at a common state. The trimer 1,3,5-trioxane, (CH 2 O) 3, is a typical oligomer.
K b & K f [1] Lauric acid: 298.9 44 –3.9 Acetic acid: 1.04 117.9 3.14 16.6 –3.90 K b [1] K f [2] Acetone: 0.78 56.2 1.67 –94.8 K b [3] Benzene: 0.87 80.1 2.65 5.5 –5.12 K b & K f [2] Bromobenzene: 1.49 156.0 6.26 –30.6 Camphor: 204.0 5.95 179 –40 K f [2] Carbon disulfide: 1.29 46.2 2.34 –111.5 –3.83 Carbon tetrachloride: 1.58 76 ...
The stock solution for Karnovsky fixative is as follows: [1] 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.