Effects of negative holding potentials at carbon-fiber microelectrodes
in TRIS buffer. (A) Fast-scan background voltammograms taken with
different holding potentials (−0.5, −0.3, −0.1,
and 0.0 V vs Ag/AgCl). (B) Amperometric current at various negative
potentials over 5 min window at various holding potentials (0.0 to
−0.8 V). (C) Slow scan voltammogram (80 mV/s, +0.7 to −1.7
V, forward scan shown only) showing significant redox current in the
negative potential region. (D) Subtracted fast-scan voltammograms
taken at various application frequencies (0.5–20 Hz), using
the voltammograms taken at 30 Hz as the blank signal.