532
A. Nosal-Wierci´ nska and W. Kaliszczak
0.4
0.2
0
-0.2
-0.4
E vs. (Ag/AgCl) /V
0
-20
-40
-60
-80
I
p /µA
6TG
6TG+Tween 80
6MP
6MP+Tween 80
AZA
AZA+Tween 80
Bi
Fig. 4 The SWV peaks of 1 : 10 −3 mol : dm −3 Bi(III) ( ) ( ) electroreduction in 2 mol : dm −3
chlorates(VII) and with 1 · 10 −3 mol : dm −3 6-mercaptopurine ( ), 1 · 10 −3 mol : dm −3 6thioguanine ( ), 1 · 10 −3 mol : dm −3 azathioprine ( ) and in the system: 1 · 10 −3 mol : dm −3
6MP + 1 · 10 −5 Tween 80 ( ); 1 · 10 −3 mol : dm −3 6TG + 1 · 10 −5 Tween 80 ( ); 1 · 10 −3
mol : dm −3 AZA + 1 · 10 −5 Tween 80 ( )
The lnk f = f (E) dependencies [10, 38, 39] (obtained by the electrochemical
impedance spectroscopy) are not linear for all the studied systems which point out to
the multi-stage process of Bi(III) ion electroreduction in 2 mol · dm
−3 chlorates(VII).
The kinetic parameters αn α and k s determined using electrochemical techniques
indicate the catalytic effect of thiopurine derivatives as well as changes of its amount
due to the presence of the 6TG–TritonX-100 i 6TG–Tween 80, 6MP–TritonX-100 i
6MP–Tween 80, or AZA–TritonX-100 i AZA–Tween 80 mixtures (Tables 2a, b).