Simultaneous Determination of Zn(II), Cd(II), Pb(II), and Cu(II) Using Differential Pulse Anodic Stripping Voltammetry at a Bismuth Film-Modified Electrode

Table 1

Factors in BBD and their levels.

Level	Accumulation potential (x1, V)	Accumulation time (x2, s)	Pulse amplitude (x3, V)	Scan rate (x4, V·s^−1)
High level (+1)	–1.0	20	0.01	0.01
Central level (0)	–1.5	100	0.05	0.02
Low level (–1)	–2.0	180	0.09	0.03

15 ppb concentration of Zn, Cd, Pb, and Cu in 500 ppb Bi and 0.1 M acetate buffer (pH 5).