(a) between the deposited DSNPs-GCE and NA were
(2.0 ± 0.05) 103 cm/s and 0.64 ± 0.02, respectively. Based on
the chronoamperometric results, the diffusion coefficient of
NA was 8.8 106 cm2/s under the experimental conditions. In
the DPV studies, the calibration curves for NA were linear in
three ranges: 833.3e166.7mM, 166.7e26.4mM, and 26.4e1.4mM.
The detection limit of NA was estimated at 0.40mM. Simultaneous
electrochemical determinations of AA, NA, UA, and
Trp were possible without electrochemical interference from
each other. This method was used for the determination of
AA, NA, and UA in real samples of urine