Q.1 how you will prepare 4% paraformaldegyde solution?
how you will prepare the solutions?
solution 1 ( 500mL; pH 8.5)
1% Tryptone + 0.5% yeast extract + 200mM NaCl.
solution 2(500mL;pH 8.8)
50mM glucose + 10mM EDTA + 25mM tris (pH 8.0)
plz answer
Answers
Answer:
For 1 L of 4% Formaldehyde, add 800 mL of 1X PBS to a glass beaker on a stir plate in a ventilated hood. Heat while stirring to approximately 60 °C. Take care that the solution does not boil.
Add 40 g of paraformaldehyde powder to the heated PBS solution.
The powder will not immediately dissolve into solution. Slowly raise the pH by adding 1 N NaOH dropwise from a pipette until the solution clears.
Once the paraformaldehyde is dissolved, the solution should be cooled and filtered.
Adjust the volume of the solution to 1 L with 1X PBS.
Recheck the pH, and adjust it with small amounts of dilute HCl to approximately 6.9.
The solution can be aliquoted and frozen or stored at 2-8 °C for up to one month.
The difference between paraformaldehyde, formaldehyde, and formalin
Paraformaldehyde (chemical name is polyoxymethylene) is a powder of polymerized formaldehyde that by itself cannot fix tissues. To be usable as a tissue fixative, paraformaldehyde has to be dissolved in hot water to become a formaldehyde solution. Formalin is a saturated formaldehyde solution in water (37% by weight, 40% by volume) containing 10-15% methanol. Methanol is added to slow down the polymerization to formaldehyde, which reduces the fixing power of formalin. Formalin can also be made in an alcohol-free form from powdered paraformaldehyde.