Detection Of Dopamine In Samples Research Articles

Electrochemical Sensing of Dopamine Using Onion-like Carbons and Their Carbon Nanofiber Composites

This work describes the electrochemical detection of dopamine in samples (pure raw materials as well as pharmaceutical formulation) using onion-like carbon (OLC) and its carbon nanofiber composites (OLC-CNF). The OLC-CNF and precursor materials (polyacrylonitrile (PAN) fiber and OLC-PAN) were synthesized using electrospinning process. The morphologies of the samples were obtained using scanning electron microscopy (SEM) while surface area and porosity were determined using the Brunauer–Emmett–Teller (BET) analysis. OLC gave the best surface area (279 m2 g−1) and highest pore volume (1.2 cm3 g−1). To determine electrochemical sensing properties, the materials were drop-cast on the glassy carbn electrode (GCE). The electron transfer properties decrease as follows: OLC > OLC-PAN > OLC-CNF > PAN, suggesting that OLC is the most conductive materials. The modified GCE were used as sensors for the dopamine using electrochemical techniques such as cyclic voltammetry (CV), square wave voltammetry (SWV), and electrochemical impedance spectroscopy (EIS). OLC and OLC-CNF gave comparable electrocatalytic activities in terms of sensitivity and limit of detection (OLC 1.23 μM and sensitivity of 0.74 μA/μM, and OLC-CNF 1.42 μM, 0.31 μA/μM). The high performance of OLC is attributed to its advantageous nanoparticulate nature and high conductivity. Both sensors (OLC and OLC-CNF) could be reliably used in the assay of dopamine raw material and its pharmaceutical formulation, dopamine HCl injection (Rotexmedica®). One of the key fndings here is that the incorporation of the CNF into the OLC does not significantly impact on its inherent tensile strain that defines its electrochemical performance.

Detection of dopamine in non-treated urine samples using glassy carbon electrodes modified with PAMAM dendrimer-Pt composites

Composites of hydroxyl-terminated PAMAM dendrimers, generation 4.0 (64 peripheral OH groups) containing Pt nanoparticles were synthesized at different reaction times using a microwave reactor. The synthetic procedure resulted in dendrimer encapsulated nanoparticles of Pt (DENs-Pt) of 1.53 ± 0.17 nm diameter that was calculated from transmission electron microscopy, and the Pt nanoparticles had single crystal plane in (1 1 1) orientation determinate by selective area diffraction. Each composite was electrochemically immobilized on a pre-functionalized glassy carbon (GC) electrode that was incorporated as a flow injection amperometric (FIA) detector, for the selective detection and quantification of dopamine (DA) in untreated urine samples. Comparison of the analytical performance of the novel electrochemical detector revealed that the DENs-Pt modified GC electrode with the composite synthesized for 30 min in the microwave reactor, showed the best response for the detection of DA in samples of non-treated urine, being the detection and quantification limits smaller (19 and 9 ppb, respectively) than those corresponding to the naked a GC electrode (846 and 423 ppb, respectively) using the FIA detector. In addition, it was found that this electroanalytical approach suffers minimal matrix effects that arise in the analysis of DA in untreated samples of urine.