Pencil Electrodes for Determination of Dopamine, Serotonin and Ascorbic Acid

Abstract

In this work a graphite pencil electrode is used to determine ascorbic acid, dopamine and serotonin. The electrochemical technique employed was cyclic voltammetry. These low cost electrodes were able to detect the biomolecules in the order of mM concentration. The oxidation peak potentials for the analytes are similar to those already reported, although a better peak definition was obtained. Also, this report includes the effect of the pH over the oxidation potential of these three species.

Pencil Lead as a Material for Microfluidic 3D-Electrode Assemblies

“…To further characterize our device we chose two proof-of-concept applications: dopamine and p -nitrophenol sensing. We have shown the possibility of dopamine detection in the range from 10 µmol L −1 to 1 mmol L −1 , which is comparable with other works on pencils [ 37 , 38 ] but is still high when set together with many currently described electrodes, or the physiological range (basal concentration of dopamine ~20 nmol L −1 in rat cerebrospinal fluid [ 39 ]). Detection of dopamine in the presence of interferents, in a physiological range is a separate challenge, as it is often impossible to separate peaks of different compounds when measured in mixture [ 40 ].…”

Edge and Basal Plane Anisotropy of a Preanodized Pencil Graphite Electrode Surface Revealed Using Scanning Electrochemical Microscopy and Electrocatalytic Dopamine Oxidation as a Molecular Probe

“…This value is relatively lower than those of several graphitic carbon electrodes chemically modified by metals and polymers (Supporting Information, Table S1). ,,− These observations highlight that the PGE* is a good choice for DA sensor application without any other fouling characteristics, unlike conventional HOPG and graphitic carbon-based electrode systems. , Further, the effect of interfering electroactive species was tested using the CA technique by spiking 5 μM DA along with the most common interfering analytes such as ascorbic acid (Asc), uric acid (UA), glucose (Glu), and cysteine (CySH) at E app = 0.2 V vs Ag/AgCl in pH 7 PBS (Figure E). There was no marked alteration in the CA current signal, depicting the appreciable selective electrochemical electroanalytical performance of the PGE*.…”

“…In this connection, ultralow-cost and ready-to-use pencil graphite electrodes, which are composed of ∼85% of graphite, 10% of clay, and 5% of wax-binder, have been referred for electroanalytical applications . Besides, the native form of the PGE is electro-inactive and requires specific surface treatments like preanodization, − thermal treatment, flame itching, and metal/metal oxide − and conducting polymer-based surface − modification procedures for the activation. Unlike the HOPG-based systems, molecular insights into the PGE surface and its activation process were not reported until date.…”

“…Hence, Ru­(NH 3 ) 6 2+ and ferrocene-based redox couples have been used as alternatives for the ferricyanide redox-probe. ,, Meanwhile, other graphitic materials like graphene and graphene oxide (GO) were subjected to SECM and their surface heterogeneity was explored . Indeed, PGE*, which showed versatile electroanalytical applications ranging from small molecule-electrochemical detection, ,,− ,− hybridization-based DNA sensing, electrochemical immunosensing, to point-of-care systems, was never subjected to the SECM analysis. In this work, using Fe­(CN) 6 3– as a redox probe, we studied the electron transfer characteristic and surface heterogeneity of the PGE*.…”

Surface-Activated Pencil Graphite Electrode for Dopamine Sensor Applications: A Critical Review

“…Hence, DA has been used as a model electrochemical probe to understand the surface feature of graphitic materials [ 46 ]. In 2008, Valencia et al first reported the simultaneous determination of DA, AA and serotonin (SE) using a PGE* [ 47 ]. A homemade sensor was prepared manually using a micropipette and epoxy resin, where the surface activation of the PGE was carried out by performing 20 continuous cyclic voltammetric measurements in a potential window of −0.6 to +0.9 V vs SCE in a N 2 purged 0.1 M phosphate buffer solution (PBS) at v = 100 mVs −1 .…”