Simple Dilutions

Posted on August 1st, 2016 by UNM CC

  1. Determine the final volume (Vf): How much to you want to make?
  2. Determine the dilution factor (d.f.). User either...
    d.f. = Cs / Cf i.e. the ratio of starting concentration / final concentration:
    d.f. = the fold concentration (e.g. 20x) of the starting material (if the final concentration is 1x)
  3. Calculate the starting volume (Vs): How much of the concentrated stock will you use?
    Vs = Vf / d.f.
  4. Calculate the diluent volume (Vd): With how much water will you dilute the stock?
    Vd = Vf - Vs

Example #1: You want to make up 1 mL of oligonucleotide N1 at a concentration of 2 µM using a stock of 50 µM using water as the diluent.

  1. Vf = 1000 µL
  2. d.f. = Cs / Cf = 50 / 2 = 25x
  3. Vs = Vf / d.f. = 1000 / 25 = 40 µL
  4. Vd = Vf - Vs = 1000 - 40 = 960 µL
    1. Thus add 40 µL of the N1 primer + 960 µL H2O.

Example #2: You want to make up 7 L of TAE buffer from a 20x stock using water as the diluent.

  1. Vf = 7000 mL
  2. d.f. = 20x
  3. Vs = Vf / d.f. = 7000 / 20 = 350 mL
  4. Vd = Vf - Vs = 7000 - 350 = 6650 mL
    1. Thus use 350 mL of 20x TAE + 6650 mL H2O.

Tags: Fero-Formulae

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