Linear regression analysis was performed for the calibration standard data set based on this experiment. The analysis yielded the following results: m = 58.8746, b = -0.0063. What is the concentration of protein (mg/mL) in the original unknown protein solution if the measured absorbance is 0.669? The absorbance of a blank solution is 0.370. Assume a dilution factor of 40 for the analyzed unknown solution.
a) 0.1971
b) 0.207
c) 0.199
d) 0.2074

Question

Linear regression analysis was performed for the calibration standard data set based on this experiment. The analysis yielded the following results: m = 58.8746, b = -0.0063. What is the concentration of protein (mg/mL) in the original unknown protein solution if the measured absorbance is 0.669? The absorbance of a blank solution is 0.370. Assume a dilution factor of 40 for the analyzed unknown solution. 
 a) 0.1971 
 b) 0.207 
 c) 0.199 
 d) 0.2074

abb0t · Answer

You're solving for "x", when you have $\sf \color{red}{y=mx+b}$
m = slope 
y = absorbance value

This will give you the concentration of the unknown sample. Since your dilution factor was 40, multiply the final concentration by 40. 
I'm assuming this is either for biochemistry or qualitative analysis, in which case, you should be very familiar with algebraic manipulation so I won't go into detail. 

But, for (1), you should get approximately 0.138 M, or 1.38 $\times$ 10$^{-1}$ M

abb0t · Answer

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