A Sonogel/L‐Cystein and a SAM L‐Cystein Modified Electrodes for Detection of Dopamine

Abstract

AbstractSummary: The Sonogel‐Carbon electrode is a special class of sol‐gel electrode that exhibits favourable mechanics and electric properties that can be used as electrochemical sensors. In this study, a Sonogel‐Carbon modified with L‐Cysteine was used to prepare a novel electrochemical sensor. The objective of this new electrode modification was to seek new electrochemical performances for thedetection of dopamine (DA). The influence of natural interferents such as Ascorbic Acid (AA) and Uric Acid (UA) was explored. The concentration of theses strong interferent was increased to a certain level in order to determine to what extends AA and UA may disturb the neurotransmitters electroanalysis. Our work showed that the modified electrode offers interesting analytical performances such as:(a) Fast and linear responses towards the neurotransmitter dopamine: The differential pulse voltammetry current peak was linear with the DA concentration in the range 2 · 10−7 M to 10−5 M with a detection limit of 4 · 10−8 M (S/N = 3).(b) Simultaneous detection and well‐resolved signals between the DA, AA and UA: The new sensor could sensitively and separately determine DA in the presence of 1000 and 900 times higher concentrations of AA and UA respectively.Optimization of parameters such as the amount of L‐cysteine in the Sonogel‐Carbon mixture, interference effect, perm‐selectivity and mechanical stability of the sensor are discussed. A comparison with a SAM L‐Cysteine/gold electrode was also made.On the other hand the new Sonogel modified electrode has been applied to the determination of dopamine in urine samples with satisfactory results.With good selectivity and sensitivity, the proposed sensor is a simple tool for the selective detection of DA, AA and UA in biological samples.