Standard Addition
An unknown sample of dopamine gave a current of 34.6 nA in an electrochemical analysis. Then 2.00 mL of solution containing 0.015 6 M dopamine was mixed with 90.0 mL of unknown, and the mixture was diluted to 100.0 mL in a volumetric flask. The signal from the new solution was 58.4 nA. Find [dopamine]i in the unknown.