Bradford Stock Solution

• This solution is mainly used to determine the concentration of proteins in solution.
• The principle of detection is based on the formation of a complex between the dye, Brilliant Blue G, and proteins in solution.
• The protein dye complex causes a shift in the absorption maximum of the dye from 465 to 595 nm. The amount of absorption is proportional to the protein present.
• The Bradford Reagent requires no dilution and is suitable for micro, multiwell plate, and standard assays. 
• This solution also compatible with reducing agents which are often used to stabilize proteins in solution.
• This solution is consist of t consists of Brilliant Blue G in phosphoric acid and methanol.
• Bradford Stock Solution is stable at 2–8 °C in an unopened container for at least 1 year.

Preparation of Bradford Stock Solution

To prepare 1L of Bradford Stock Solution, the following components are required;

Component	Amount	Concentration
Ethanol (95%) (mw: 46.07 g/mol)	333 mL	31.67 %
Phosphoric acid (88%) (mw: 58.4 g/mol)	667 mL	58.67 %
Coomassie Brilliant Blue (mw: 825.97 g/mol)	1.16 g	1.41 M

Procedure

1. Prepare 0 mL of distilled water in a suitable container.
2. Add 333 mL of Ethanol (95%) to the solution.
3. Add 667 mL of Phosphoric acid (88%) to the solution.
4. Add 1.16 g of Coomassie Brilliant Blue to the solution.
5. Add distilled water until volume is 1 L.

References

• “Bradford Stock Solution Preparation.” AAT Bioquest, Inc, 04 May. 2021, https://www.aatbio.com/resources/buffer-preparations-and-recipes/bradford-stock-solution.
• https://www.sigmaaldrich.com/content/dam/sigma-aldrich/docs/Sigma/Bulletin/b6916bul.pdf