Each parameter in the MSW (vide supra) was varied systematically. The assumption is that these parameters behave independently from each other, and, from our experience, there has been no evidence indicating otherwise. Figure -3f summarizes the results from the optimization of MSW waveform parameters for maximal sensitivity towards Trp detection. Maximum sensitivity towards Trp detection was observed at intermediate values that we tested for the holding potential, transition potential, and switching potentials. The utility of the holding potential is to: 1) oxidize interfering species such that their anodic currents become part of the background signal (and can be subtracted out -this applies for serotonin detection, for example, due to the positive holding potential ; and/or 2) preconcentrate analytes of interest through electrostatic interactions -this applies for dopamine, for example . Here, a (-)0.3 V holding potential yielded the maximal sensitivity, which makes sense as at pH 7.40, the majority of the Trp molecules have a positive charge on the amino terminal group, so a negative surface potential on the electrode would preconcentrate it onto the electrode surface. It is possible that scanning the holding potential to even more negative values would preconcentrate interfering species, thereby lowering the sensitivity for Trp. The optimal transition potential was +0.6 V. The transition potential is the point where the scan rate switches from 100 V/s to higher scan rates and should precede the potential at which we expect our primary oxidation peak. At potentials between the holding and transition potential, the resulting currents were significantly lower due to the slower scan rate (i.e. 100 V/s). Thus, the smaller oxidation peak in Trp observed by others (~0.43 V in Weese-Myers et al. ) was not apparent in our CVs. Others have observed similar phenomenon using the multi-scan rate sawhorse waveform .