Table 2.

The life time of electrode.

Number of days	Slope (mV/decade)	Linear range (mM)
1	41.33 ± 1.58	1 × 10−4–1 × 100
7	42.57 ± 1.82	1 × 10−4–1 × 100
14	41.39 ± 1.72	1 × 10−4–1 × 100
21	40.80 ± 1.84	1 × 10−4–1 × 100