The corresponding calibration plot in coordinates: 1,2-
benziquinone cathodic current vs. the logarithm of the trypsin
concentration is shown in Fig. 5. Its shape was similar to that of
the calibration plot obtained applying Sensor 1, i.e. it consisted
of two linear parts with different slopes. The sensitivity of the
determinations was found to be 0.40 A mL g−1 in the range from
0.1 g mL−1 to 10 g mL−1, and 1.02 A mL g−1 in the range from
100 g mL−1 to 1000 g mL−1, respectively. The limit of detection
was established at 0.01 g mL−1 trypsin after 140 min incubation
time. The reproducibility of the determinations evaluated as indicated
in Section 3.2 was found to be similar of that, reached with
Sensor 1 (RSD < 3%).