This paper presents a sensitive electrochemical
method for the determination of cysteamine (CA) using
promazine hydrochloride-modified multi-wall carbon nanotubes
carbon paste electrode (PrH/MWCNTs CPE). Because
of the good electrochemical activity of MWCNTs and the
acceptable performance of promazine hydrochloride (PrH)
as an electrocatalytic mediator, the modified electrode significantly
enhanced the sensitivity for the detection of CA in
comparison to the bare carbon paste electrode (CPE). All
chemical parameters such as pH of solution, concentration
of PrH and kinetic parameters of the system were investigated.
Linear sweep voltammetric (LSV) method was used to follow
the electrocatalytic effect of CA on the current–potential response
of PrH. Under optimum conditions, the obtained net
peak current ΔIp(Isample−Iblank) was linear with CA concentrations
in two dynamic ranges of 2.0–346.5 μmol l−1
(ΔIp=(0.0195±0.0043)CCA+(0.7648±0.0397) (r2=0.9948))
and 346.5–1,912.5 μmol l−1 (ΔIp=(0.0100±0.0026)CCA+
(3.8981±0.0828) (r2=0.9911)) with a detection limit of
0.8 μmol l−1. Finally, the PrH/MWCNTs CPE was successfully
applied for the determination of CA in urine and drug
samples with satisfactory results.