Spectrophotometric Determination of Iron(II) and Cobalt(II) by Direct, Derivative, and Simultaneous Methods Using 2-Hydroxy-1-Naphthaldehyde-p-Hydroxybenzoichydrazone

Table 10

Tolerance limit of foreign ions (μg mL⁻¹).

Diverse ion	Zero order	Second derivative	Third derivative
Th(IV)	6	55	35
U(VI)	5	40	45
Mn(II)	5	60	20
Cu(II)	2	80	45
Ni(II)	<1	30	50
Zn(II)	<1	45	20
Sn(II)	<1	25	18
In(III)	<1	15	28
Ga(III)	<1	20	35
V(V)	<1	15	20