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

Table 7

Tolerance limits of foreign ions, amount of Co(II) taken = 1.767 μg mL⁻¹, pH = 6.0.

Foreign ion	Tolerance limit (μg mL^−1)	Foreign ion	Tole limit (μg mL^−1)	Foreign ion	Toler limit (μg mL^−1)
Tartrate	1707	Na(I)	1666	Au(III)	20
Phosphate	1425	Mg(II)	1530	Sr(II)	18
Sulphate	1440	Ca(II)	1426	Mo(VI)	15
Oxalate	1320	K(I)	1200	Tl(IV)	13
Bromide	1198	Ba(II)	1162	Pd(II)	11,100^c
Thiourea	1140	Hf(IV)	72	Th(IV)	6,60^a
Thiosulphate	1120	Se(IV)	64	U(VI)	5,60^a
Nitrate	930	Cd(II)	56	Mn(II)	5,50^a
Chloride	525	W(VI)	55	Cu(II)	2,50^a
Carbonate	300	Zr(IV)	46	Ni(II)	<1,80^b
Fluoride	285	Pb(II)	42	Zn(II)	<1
EDTA	144	Hg(II)	40	Sn(II)	<1
Citrate	115	Cr(VI)	26	In(III)	<1,60^a
		Bi(III)	21	Ga(III)	<1,50^a
		Ru(III)	21	V(V)	<1,50^b

In the presence of 𝑎=700 μg of tartrate, 𝑏=400 μg of oxalate and 𝑐=500 μg of thiourea.