Question #12905

1 Answer
Feb 14, 2017


I'm not sure what you did, but I don’t think it was correct.


First, you prepared a standard curve, in which you plotted the absorbances of known concentrations of the drug.

I presume you got a graph something like this.


You use this plot to determine the concentration of your unknown.

Then you diluted your unknown sample by a factor of 1000 (?).

You measured its absorbance and got a value of 0.247.

From the regression equation, #y = 0.045x + 0.0273#, you get

#x = (y-0.0273)/0.045 = (0.247-0.0273)/0.045 = 0.2197/0.045 = 4.88#

The concentration of the drug in your diluted sample was 4.88 µg/mL.

Thus, the concentration in your original sample was 4.88 mg/mL or 48.8 mg/10 mL.