Table 1.

The equation coefficients (I_p = ac_m + b) and the coefficient of determination (r²) for each individual heavy metal ion (Zn(II), Cd(II), Pb(II), and Cu(II)) and for the mixture solution determined by the Cr-CPE.

Electrode Type	Detected Ion	a	b	r2
Cr-CPE	Zn(II)	0.0109	−0.4783	0.9905
(individual ions)	Cd(II)	0.0177	1.5649	0.9890
	Pb(II)	0.0566	−0.6693	0.9952
	Cu(II)	0.1104	0.4032	0.9904
Cr-CPE	Zn(II)	0.0096	−0.4081	0.9900
(mixture solution)	Cd(II)	0.0103	1.1684	0.9934
	Pb(II)	0.0710	0.7963	0.9941
	Cu(II)	0.1244	3.9573	0.9934