Interference test of nitrate ion selective electrode (Mean ± SD, n = 3).

Table 3: Interference test of nitrate ion selective electrode (Mean ± SD, n = 3).

Sample	Measured [NO₃^-] (μM)	Interference Coefficient
Celery juice	114.4 ± 5.3	N/A
Celery juice + 100 μM NO₂^-	114.7 ± 5.4	0.3%
Celery juice + 100 μM C₂O₄^2-	117.9 ± 0.2	3.5%
Celery juice + 100 μM Cl^-	119.3 ± 2.2	4.9%
Celery juice + 100 μM SO₄^2-	119.5 ± 2.3	5.1%
Celery juice + 100 μM ClO₃^-	165.5 ± 5.6	51.1%
Celery juice + 10.0 μM ClO₄^-	148.7 ± 5.1	343%