An Amperometric Biosensor Based on Alanine Dehydrogenase for the Determination of Low Level of Ammonium Ion in Water

Table 2

Data for shelf life study of AlaDH enzyme-based electrode tested in solution containing 1.53 mg/L 𝑁𝐻₄⁺ ion, 0.25 mM NADH, and 0.01 mM pyruvate at pH 7 over a period of 11 days (𝑛=3).

Time (day)	Current Difference (× 10^−7 A)	Standard deviation	Relative response (%)
1	0.828	0.023	100.0
3	0.332	0.076	40.1
5	0.243	0.049	29.3
7	0.223	0.055	26.9
9	0.222	0.081	26.8
11	0.205	0.131	24.7