2-Hydroxy-1-naphthaldehyde-P-hydroxybenzoichydrazone: A New Chromogenic Reagent for the Determination of Thorium(IV) and Uranium(VI)

Table 10

Analytical properties of [Th(IV)-HNAHBH] and [U(VI)-HNAHBH].

	Direct method		Second derivative
Parameter	Thorium	Uranium	Thorium		Uranium
	415 nm	410 nm	434 nm	453 nm	459 nm	477 nm
Beer’s law range (μg mL^−1)	0.464–6.961	0.476–7.140	0.232–6.961	0.232–6.961	0.238–2.38	0.238–2.38
Molar absorptivity, (L mol^−1 cm^−1)	3.5×10^4	1.78×10^4	—	—	—	—
Sandell’s sensitivity, μg cm^−2	0.007	0.0134	—	—	—	—
Angular coefficient (m)	0.365	0.0827	0.0007	0.0006	0.0001	0.0001
Y-intercept (b)	0.0013	0.0081	−0.9×10^−3	−0.9×10^−3	−0.6×10^−4	0.5×10^−4
Correlation coefficient (r)	0.9999	0.9994	0.9998	0.9998	0.9999	0.9999
RSD	0.335	1.65%	1.46	0.17	0.98%	2.25
Detection limit (μg mL^−1)	0.01	0.139	0.014	0.044	0.03	0.067
Determination limit, μg mL^−1	0.03	0.417	0.043	0.132	0.09	0.2
Composition (M : L)	2 : 3	1 : 1	—	—	—	—
Stability constant	2.72×10^19	3.3×10^5	—	—	—	—