Title: Concentrated Stock Solutions
Course: BTEC-1100-301-302-303-F21 > Section: Module 1 - Calculations and Measurements

Concentrations may also be described in comparison to the standard working concentration of the solute. For example, the 1x TAE you have used to make and run agarose gels is often made at a concentration twenty times greater than the 1x TAE. We call this stock solution 20x TAE. When more 1x TAE is needed, we can take 1 part 20x TAE, and add 19 parts dH2O, to make 20 parts of 1x TAE. Diluting a stock solution is much easier than making the solution from scratch.

Example: You have 20x TAE stock, and need 1 L (1000 mL) of 1x TAE.

- To dilute a stock from 20x to 1x, you need one twentieth (1/20) of the final volume to be the 20x stock. The desired volume is 1000 mL.
- 1000 ml / 20 = 50 mL
- This means that 50 mL of 20x TAE stock should be diluted with dH2O into a total volume of 1000 mL to make 1x TAE.