A Modified o-Phthalaldehyde Fluorometric Analytical Method for Ultratrace Ammonium in Natural Waters Using EDTA-NaOH as Buffer

Table 3

Calibration curves and the corresponding performances.

Method	Excitation/emission slit widths	Calibration curves			Standard deviation of the intercept	Standard deviation of the slope	Linearity range (μmol/L)
	3 nm/5 nm	FI =	6	0.9970	11.90	38.87	0.032–0.500
The proposed method	3 nm/3 nm	FI =	6	0.9996	4.88	2.94	0.25–3.00
	1.5 nm/1.5 nm	FI =	8	0.9971	5.58	0.81	1.00–15.0
The classical method	3 nm/5 nm	FI =	6	0.9951	5.71	12.66	0.25–2.00