It appears that there is insufficient information to derive a reasonable conclusion. Here are a few questions that I have:
1) What is the intercept if it is approximately zero (is an actual value provided?)
2) What are the molar concentration measured?
The reason why I ask these questions are:
1) given: A/E= molar concentration, if the molar concentration is 1.0 at the given absorbance, then the calculated value is 2.100x10-4. If you are given a different molar concentration, then this would change the value.
2) if the intercept is not zero, this will change the slope value (it could explain the difference between 2.128x10-4 and 2.100x10-4)
I hope this helps,
Eugene Dakin Ph.D., P.Chem.