Preparation of 3 M Sodium acetate (CH3COONa), pH 5.2 solution from CH3COOH.3H2O

Overview

  • Sodium acetate is a sodium salt of acetic acid.
  • It is water-soluble.
Related Content

Requirements

  • Reagents
    • Sodium acetate, trihydrate (CH3COONa.3H2O) (Molecular weight = 136.08)
    • Deionized / Milli-Q water
  • Equipment and disposables
    • Measuring cylinder
    • Conical flask / Beaker
    • Magnetic stirrer

Composition

  • 3 M Sodium acetate

Objective

Preparation of 100 ml of 3M Sodium acetate solution, pH 5.2 in water from sodium acetate trihydrate (CH3COONa.3H2O)

Preparation

Step 1: To prepare 100 ml aqueous solution of 3M Sodium acetate (CH3COONa), weigh out 40.82 gram CH3COONa.3H2O (Molecular weight = 136.08). Transfer it to 250 ml beaker/conical flask. Add 80 ml deionized / Milli-Q water. Mix until all sodium acetate dissolves completely.

Tip:
  • One can use manual shaking using a glass pipette to mix the ingredients. Magnetic stirrer makes the dissolving process easy and convenient.
Precaution:
  • Do not dissolve in 100 ml of deionized / Milli-Q water. In most cases, solution volume increases when a large amount of solute dissolves in the solvent.

Step 2: Adjust the pH to 5.2 with glacial acetic acid.

Precaution:
  • Since pH is dependent on temperature, one should adjust pH at room temperature (25°C).

Step 3: Adjust the volume to 100 ml with deionized / Milli-Q water. Mix it again.

Note:
  • The solution will appear colorless and transparent.

Step 4: Transfer the solution to autoclavable bottle. Sterilize the solution by autoclaving (20 minutes at 15 lb/sq.in. (psi) from 121-124°C on liquid cycle).

Tip:
  • Depending on the consumption, one can make small aliquots of the solution.
Note:
  • One can sterilize a solution by passing through 0.2μ filter unit. Filter sterilization removes all suspended particles with size more than 0.2 μ which includes most bacteria and their spores but not mycoplasma. Moreover, it does not inactivate enzyme activities (e.g., DNases). Autoclaving inactivates most enzymes except some (e.g., RNases) and kills most microorganisms including mycoplasma.

Storage

Solution can be stored at room temperature.

Applications

  • Precipitation of nucleic acid (DNA and RNA)
  • Buffer solution
  • Protein crystallization
Follow the table, to prepare Sodium acetate (CH3COONa) solution of specific concentration and volume from CH3COONa.3H2O.
Conc. / Volume 10 ml 50 ml 100 ml 250 ml 500 ml 1000 ml
0.1 M 0.136 g 0.68 g 1.36 g 3.40 g 6.80 g 13.61 g
0.5 M 0.68 g 3.40 g 6.80 g 17.01 g 34.02 g 68.04 g
1 M 1.36 g 6.80 g 13.61 g 34.02 g 68.04 g 136.08 g
3 M 4.08 g 20.41 g 40.82 g 102.06 g 204.12 g 408.24 g