Table 1.

Simultaneous fourth-order derivative determination of Co(II) and Ni(II) in synthetic binary mixtures.

Amount taken (μg mL−1)		Amount found* (μg mL−1)		Relative error (%)
Co(II)	Ni(II)	Co(II)	Ni(II)	Co(II)	Ni(II)
0.2357	0.2347	0.2362	0.2340	+0.21	−0.29
0.2357	0.4694	0.2352	0.4685	−0.21	−0.23
0.2357	0.7041	0.2354	0.7049	−0.12	+0.11
0.2357	0.9388	0.2361	0.9382	+0.16	−0.06
0.2357	1.1785	0.2365	1.1780	+0.33	−0.04
0.2357	0.2347	0.2362	0.2352	+0.21	+0.21
0.4714	0.2347	0.4708	0.2344	−0.10	−0.12
0.7071	0.2347	0.7081	0.2354	+0.14	+0.29
0.9428	0.2347	0.9420	0.2340	−0.08	−0.29
1.1735	0.2347	1.1742	0.2362	+0.05	+0.63

*Average of five determinations.