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Reagents 1

Reagents 1 — Dilution from Stock Solutions

 
You are to make up a reaction mixture with a specified final volume. You are given a stock solution of a component at a certain concentration, and you have to calculate the volume to add to the reaction mixture to obtain a particular final concentration.

Volume to add: µl   
 
You should aim to do these calculations in your head or on a scrap of paper (i.e. without a calculator). The following logic may be helpful:
  • You are diluting a stock solution.
  • The extent of the dilution is the final concentration divided by the stock concentration.
  • This is the same as the volume of added stock divided by the final volume.
  • The volume required is therefore:
    final volume x (final concentration/stock concentration)
Always do a ‘sanity check’ on your answer. Is it the right order of magnitude? E.g. for a dilution factor of 8.5, round this up to 10 and check whether your answer is somewhere near one-tenth of the final volume (rather than one hundredth).