HighPoint/CannonLab:Buffer and Osmolyte Solutions

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Revision as of 17:17, 23 February 2012

Preparing Buffers

Always wear gloves to avoid contamination of your solutions with bacteria!

Stock Solutions

1. Prepare stock solutions of buffer components (typically 1 M)
2. Rinse clean storage bottle and filter flask an extra time
   • Use type I, 18 MΩ purified water
   • Drain and use your best aseptic technique from this point on
3. Filter stock solutions through 0.2 μm filter
4. Store in bottle for future use
   • Keep the bottle closed as much as possible
   • Always wear gloves and use clean instruments for removing aliquots
   • This will extend the life of your stock solution before bacteria begin to grow in it

Filtering

Nalgene Filter Assembly

Filter Flask

• The filtration assembly is put together as in the image on the left
  1. Place a 45 mm diameter, 0.2 μm pore size filter between the top and bottom halves
  2. Close with the metal clamp
  3. Place the entire assembly onto the mouth of a filter flask
  4. Attach the side arm to an aspirator
  5. Fill the reservoir with the solution to be filtered
• Repeat step 5 until the entire solution is filtered
• If the speed of filtration reduces drastically, consider replacing the filter membrane

General rules for solution prep

Adjusting pH

Useful Recipes

1 M K₂HPO₄

1 M KH₂PO₄

1 M NaAcetate

1 M Acetic Acid

pH 7 buffer, 10 mM Phosphate, 50 mM NaCl