For switching potential, we discovered that a switching potential of +1.1 V yielded the highest selectivity ratio (Figure ). This contrasted with the +1.2 V switching potential determined to yield the maximum sensitivity. Here, the relative loss of selectivity/gain of sensitivity were relatively comparable (~20-25%) so we opted to go with +1.1 V in favor of slightly higher selectivity for a slight loss in sensitivity. For switching potential duration, 2 ms was the optimal condition that yielded the maximum sensitivity and selectivity (Figure ). In contrast to sensitivity results for scan rate, 600 V/s yielded the highest selectivity for Trp signals over Tyr and we decided to favor selectivity at the slight sacrifice of reduced sensitivity.