BSA Concentration Calculator

Bovine serum albumin (BSA), as its name suggests, is serum albumin obtained from bovine, or cows. It has long found use as a biological protein standard, because it is a well-studied, fairly non-reactive protein of known mass. It is also commonly used as an immunoassay blocker. Samples of cells or tissues are often pre-incubated with BSA to reduce non-specific binding by the antibody of interest.

The concentration of BSA in solution can be determined by substituting the molecular weight, extinction coefficient and λ _max into a derived form of the Beer - Lambert Law. A substance's λ_max is the wavelength at which it experiences the strongest absorbance. For BSA, this wavelength is 280 nm.

The absorbance at λ_max can be measured using a spectrophotometer. There are some important things to keep in mind when measuring 280 absorbance:

1. The BSA should be well-dissolved in solution. BSA precipitation will cause inaccuracies in concentration calculations.
2. The absorbance reading should not exceed the maximum detection limit of the instrumentation. This can be identified by a plateau in the absorbance spectrum. If the absorbance spectrum plateaus, dilute the sample and try again.
3. This calculator assumes a 1 cm pathlength for instrumentation. Standard cuvettes for spectrophotometers are typically 1 cm. If a different pathlength is used, value should be corrected during data entry.