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

Table 1

Tolerance limits of foreign ions, Amount of Fe(II) taken = 0.558 μg mL⁻¹ pH = 5.0.

Foreign ion	Tolerance limit (μg mL^−1)	Foreign ion	Tolerance limit (μg mL^−1)	Foreign ion	Tolerance limit (μg mL^−1)
Sulphate	1440	Na(I)	1565	La(III)	18
Iodide	1303	Mg(II)	1460	Ag(I)	15
Phosphate	1424	Ca(II)	1440	Hg(II)	16
Thiosulphate	1424	K(I)	1300	U(VI)	6,60^a
Tartrate	1414	Ba(II)	1260	Mn(II)	4,55^a
Thiourea	1140	Pd(II)	63	Th(IV)	3,50^a
Bromide	1138	Cd(II)	45	In(III)	4,60^a
Nitrate	930	Bi(III)	42	Sn(II)	<1,50^a
Carbonate	900	W(VI)	37	Co(II)	<1,55^a
Thiocyanate	870	Hf(IV)	36	Ni(II)	<1,60^b
Chloride	531	Ce(IV)	28	Zn(II)	<1,80^b
Fluoride	285	Cr(VI)	27	Al(III)	<1,45^a
EDTA	124	Mo(VI)	22	Cu(II)	<1,50^a
Citrate	115	Zr(IV)	19
Oxalate	95	Sr(II)	18

In the presence of a=500 μg of tartrate, b=400 μg of thiocyanate.