Shreffler:Standard Buffers Solutions Media: Difference between revisions
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== Buffers == | == Buffers == | ||
=== Overview === | |||
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 <sup>[A-]</sup>/<sub>[HA]</sub> | |||
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]]) === | === 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-3H<sub>2</sub>O (136 g/mol) | |||
*1.3 g Glacial Acetic acid (60 g/mol) | |||
*Bring to 1 L with dH<sub>2</sub>O | |||
adjust pH down with acetic acid or up with NaOH; dilute to desired molarity with dH<sub>2</sub>O | |||
== Media == | == Media == | ||
=== [[LB]] | === [[LB]] === | ||
'''Luria Bertani Media''' | |||
Modified to make 0.5 L | Modified to make 0.5 L | ||
Latest revision as of 19:45, 27 May 2009
Many of these are available at Materials and to reduce redundancy those are referred to and this page is not included in the Protocols or Materials categories.
This page contains lab-specific details -- please edit.
Buffers
Overview
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
Media
LB
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)
