Please do not adjust margins unmodified electrode. As seen in Figure , the current density observed for the Cu(II) reduction peak (-0.7 V vs. pseudo-Ag/AgCl) increased for the same Cu(II) concentration as the number of scans of DEB deposition increased. The highest number of scans we tested was three, which yielded three-fold higher signal for Cu(II) than a bare electrode. We performed FSCV on the same bare and DEB (3 scans)-modified electrodes over 6 days and found that the enhanced sensitivity for DEBmodified electrodes (green, Figure ) remained stable for up to 4 days when stored under room-temperature. After day 4, the 3-scan coated DEB electrode observed a significant drop in signal (p = 0.0069 comparing day 3 and 5, p = 0.0203 comparing day 3 and day 6). There were no statistical differences between days 1-4 DEB-coated electrodes. There were no statical differences between days 1-6 for bare electrodes. Next, we monitored the response of the bare and modified electrodes to Cu(II) in the presence of equal-molar interfering divalent species (ions (Mg(II), Zn(II) Ca(II))). This means that the total concentration of the other metal ions is three times as high as Cu(II) in the solution. We compared the relative current density (the ratio of current density of the electrode of interest to that of the bare electrode) to quantitatively evaluate whether the presence of interfering species affected the elevated signal. Even though the presence of the other metal ions did attenuate the signal of the modified electrode, the multi-scan DEB-coated electrodes (green in Figure ) still displayed 1.5 times higher sensitivity. The single deposition of DEB (purple, Figure ) had the same response as that of bare. When we further monitored the response of the electrodes to the mixture of divalent metal ions (without Cu(II), we discovered some interesting results. The bare electrode yielded anodic current densities (Figure ) for mixtures of metal ions, with broad peaks. In the presence of equal molar Cu(II) and the same mixture of Mg(II), Zn(II), and Ca(II), the anodic current was supplanted by a cathodic current. Note that the total concentration of other divalent metal ions in these mixtures were 3-fold that of Cu(II). DEB-modified (3 scans) electrodes yielded cathodic currents for the mixed metals as well as mixed metals plus Cu(II). The signal of the modified electrodes for mixed metals with Cu(II) was 17.4 (± 0.1)-fold higher than that for mixed metals alone. This increase was higher than that observed for bare electrode (Figure ). These results suggest that perhaps the DEB coating increase electroplating or preconcentration of other divalent metals on the CFM surface, as indicated by the change of cathodic to anodic currents, this increase was greatest for Cu(II), yielding the highest sensitivity for it over other divalent ions. Combined with data from Figure , these results suggest that the attenuation of Cu(II) signal by the other metal ions can be attributed to the presence of other ions shielding Cu(II) and/or due to some Faradaic interactions between other ions and DEB-coating. Nevertheless, even with a 3-fold higher molar equivalence of other divalent ions, the sensitivity of DEB-modified CFM for Cu(II) remained elevated.