Next, we investigated fouling on the electrode surface as a function of multiple repeated injections of Trp using the optimized waveform (Figure ). A one-way ANOVA Dunnett's T3 multiple comparison test revealed that there is no statistical difference between any of the 25 consecutive injections. Thus, we conclude that with the optimized waveform, multiple consecutive injections of at least 25 should not cause any fouling on the electrode surface. Lastly, we performed Trp measurements in cultured PC-12 cells and pinealocytes as proof-of-principle to demonstrate our ability to measure different Trp dynamics (both exogenous and endogenous changes). While we may be the first to use FSCV at CFMs to measure Trp in cell cultures, are not the first to use FSCV to measure Trp-containing compounds in cell cultures. In fact, the Venton lab first demonstrated the utility of using FSCV at CFMs to measure gonadotropin-releasing hormone, which contains and Tyr . Moreover, Kennedy and colleagues utilized FSCV at CFMs to measure a-melanocyte stimulating hormone and other Trp-and Tyr-containing oligopeptides . The authors reported comparable temporal resolution as our method reported here but utilized a slightly larger fiber (9 µm in diameter) beveled at 45 o into a disc electrode. Assuming an elliptical shape of the electrode, this would translate to a current density of ~4 pA/µm 2 for the authors' highest observed Trp or Trp-containing peptide. In contrast, with our method, we observe a nearly 2fold higher current density under comparable conditions. Moreover, we perform further optimization for selectivity here.