Absorbance and protein concentartion

Question

If tube B has an absorbance value of .158, what is the diluted protein concentration?

y=.8543x + .0375

Answer 1

Absorbance is calculated using the equation Abs = abc, where a is the molar extinction coefficient, b is the path length, and c is the concentration of the substance being measured. The extinction coefficient is specific for each substance being measured based on how it absorbs the wavelength being used for the absorbance measurement. You will need this to do the calculation The path length is usually 1 cm, and the units of the extinction coefficient are usually concentration/cm, so the path length cancels out. So if the extinction coefficient is known, then you can divide the absorbance (Abs) by the extinction coefficient and get the concentration.

You also seem to have a graph, and you could read the concentration off the graph provided there are units for the y-axis. Using an Abs of 0.158 for x in the equation gives 0.17248 for y, but since you only have three significant figures you should report this as 0.172 of whatever unit you have for the y-axis.