5-20. Standard addition graph. The figure shows standard additions of Cu2+ to acidified tap water measured by an electrochemical method. The standard additions had negligible volume compared with that of the tap water sample, so you can consider all solutions to have the same volume. The signal is the peak height (in μA), which you will need to measure relative to the baseline in the figure. Find the concentration of Cu2 in the tap water. F in U 5 ar 時罩 p 120 Current (µA) 2.0 1.6 1.2 0.8 0.4 +500 ppb +400 ppb +300 ppb +200 ppb +100 ppb Tap water Baseline Π u pe he 0.1 0.2 Potential (V vs Ag|AgCl) Ho 0.3 0.4 5-2 are Five standard additions of 100 ppb Cu2+ to tap water. [From M. A.