Shreffler:Standard Buffers Solutions Media

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Buffers are solutions of acids and conjugate bases (salts). The pH is determined by the pKa of the acid and the ratio of acid to base according to the following formula:

pH = pKa + log [A-]/[HA]

The buffering capacity is determined by the concentration and how close the pH is to the pKa (the closer, the better).

Phosphate Buffered Saline (PBS)

Sodium Acetate Buffer

The pKa of Acetic acid is about 4.75

50 mM, pH 4.5

  • 3.8 g NaAc-3H2O (136 g/mol)
  • 1.3 g Glacial Acetic acid (60 g/mol)
  • Bring to 1 L with dH2O

adjust pH down with acetic acid or up with NaOH; dilute to desired molarity with dH2O



Luria Bertani Media

Modified to make 0.5 L

  • Dissolve:
    • 5g of tryptone,
    • 2.5g of yeast extract, and
    • 5g of NaCl in 450 mL of dH2O
  • Place on stirring plate with stir bar and allow to mix, until everything dissolves
  • After completely dissolved, bring the volume up to 500 mL
  • Divide into two 150 ml flasks and store remaining in a sterile bottle
  • Autoclave the two flasks and sterile bottle (30 min)