As expected, the concentration of the unknown will have some error which can be calculated from the formula below. This formula assumes that a linear relationship is observed for all the standards. It is important to note that the error in the concentration will be minimal if the signal from the unknown lies in the middle of the signals of all the standards (the term  goes to zero if )
*, is the standard deviation in the residuals
* is the slope of the line
* is the y-intercept of the line
* is the number of standards
* is the number of replicate unknowns
* is the measurement of the unknown
* is the average measurement of the standards
* are the concentrations of the standards
* is the average concentration of the standards