IgG Concentration Calculator

Immunoglobulin G (IgG) is the most common class of serum antibody. Antibodies of this class contain two identical heavy chains (50 kDa each) and two identical light chains (25 kDa each) for a total mass of 150 kDa. IgGs are particularly useful for their application in enzyme-linked immunosorbent assays (ELISAs).

The concentration of IgG 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 IgG, 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 IgG should be well-dissolved in solution. IgG 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.