Detecting elevations as low as 100 pM Zn with FluoZin-3. The solution contained 500 nM FluoZin-3 and 10 μM Ca-EDTA in Hepes buffered saline. 'H2O' indicates the addition of 2 μl water. The trace was subjected to a 7 point Savitzky-Golay smoothing procedure. The solid line is the mean of the data acquired between 0 and 2 min, and the dotted lines the SDs.