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

Table 15

Simultaneous second-order derivative spectrophotometric determination of Fe(II) and Co(II).

Amount taken (μg mL^−1)		Amount found* (μg mL^−1)		Relative error (%)
Fe(II)	Co(II)	Fe(II)	Co(II)	Fe(II)	Co(II)
0.06	0.59	0.053 (96.3)	0.572 (98.8)	−3.6	−2.8
0.12	0.59	0.120 (103.4)	0.592 (100.5)	3.44	0.5
0.23	0.59	0.230 (99.1)	0.586 (99.4)	−0.86	−0.5
0.33	0.59	0.334 (101.2)	0.572 (98.8)	1.21	−2.8
0.44	0.59	0.441 (100.2)	0.590 (100.1)	0.22	0.2
0.55	0.59	0.542 (98.5)	0.586 (99.3)	−1.45	−0.5
0.33	0.59	0.328 (99.3)	1.120 (94.9)	−0.60	−0.7
0.33	1.18	0.326 (89.6)	2.280 (96.6)	−1.21	−5.0
0.33	2.36	0.324 (98.1)	3.600 (101.7)	−1.81	−3.3
0.33	3.54	0.336 (101.8)	4.670 (98.9)	1.81	1.6
0.33	4.72	0.332 (100.6)	4.670 (98.9)	0.60	−1.0

* Average of four determinations.