How would you calculate the concentration of an unknown solution using a standard addition method?

• A. Add known volumes of a standard to the unknown, measure response, plot response versus added standard, and extrapolate to zero added to find the initial unknown concentration.
• B. Add known volumes of the unknown to a standard, measure response, plot response versus added, and extrapolate to infinite added to find concentration.
• C. Prepare a calibration curve using the unknown and apply it to the unknown directly.
• D. Dilute the unknown until the response matches a standard.

Answer: (A)