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Chemistry LibreTexts

1. Solution Preparation

When developing a method for performing Capillary Electrophoresis, multiple solutions (aqueous buffers, background electrolytes, flushing solutions) may be required. Aliquots of each solution should be filtered and degassed prior to use. Filtering the solution removes many particulate contaminants while degassing a sample prevents capillary blockage due to bubble formation. The following is common protocol when preparing solution aliquots for use:

  1. Refrigerated solutions need to be warmed to room temperature prior to filtering. It is recommended that filtering is performed with a membrane filter with a pore size not exceeding 0.45μm. Syringe filters work best for small volumes, while vacuum filtratration is more adaptable to large volumes. The aliquot should be filtered into a clean beaker or other clean, suitable glass vessel.
  2. The filtered solution may be degassed by one of two methods. The first method involves sonicating the solution for approximately 10 minutes. Sonication may be carried out in a water bath if necessary. One must be careful to avoid sonicating too long, causing the aqueous component to evaporate, thus concentrating the solution. The second method involves placing the filtered solution into a vacuum dessicator and vacuum degassing for approximately two minutes. Once again one must avoid degassing for too long due to evaporation concerns.
  3. Once removed from the sonicator/vacuum dessicator, the beaker should be covered to prevent interchange with the air, and stored at room temperature until needed. If the filtered solution is sufficiently jostled due to rough transport, it may need to be degassed a second time.
  4. This process should be repeated for each solution, every day.