Protein x has an absorptivity of 0.4 ml·mg-1 ·cm-1 at 280 nm. what is the absorbance at 280 nm of a 2.0 mg ·ml-1 solution of protein x? (assume the light path is 1cm).

Absorbance measures the ability of the substance to absorb light at a specific wavelength.

Absorbance is also equal to the product of molar absorptivity, path length and molar concentration.

The mathematical expression is given as:

      (1)

where, A = absorbance

=  molar absorptivity

l = path length

c  = molar concentration.

The above formula is said to Beer's Law.

Absorptivity of protein x  =

Path length = 1 cm

Molar concentration =

Put the values in formula (1)

=

Thus, absorbance at 280 nm =

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