Rapid electrochemical method for the determination of L-DOPA in extract from the seeds of Mucuna prurita

Dalibor M Stanković, Anchalee Samphao, Biljana Dojcinović, Kurt Kalcher

This work presents the electrochemical behavior of levodopa (L-DOPA), at boron-doped diamond (BDD) electrodes, using cycling voltammetry (CV), in Britton-Robinson (BR) buffer solution, and application of the proposed electrode for the determination of L-DOPA in extracts from the seeds of velvet bean (Mucuna prurita Hook or Mucuna pruriens (L.) DC.). L-DOPA provides a well-defined and single oval-shape oxidation peak at +0.8 V vs. Ag/AgCl (3 M KCl) reference electrode in BR buffer solution at pH 3.0. Experimental parameters, such as pH of supporting electrolyte and square wave voltammetry (SWV) operating parameters (frequency and modulation amplitude) were optimized. The effect of possible interferences was evaluated. Under optimal conditions the detection limit of the developed method was 0.8 μM and the calibration curve for L-DOPA was linear in the range from 2 to 100 μM. The proposed method was successfully applied to the determination of L-DOPA in an extract from the seeds of Mucuna prurita. The obtained result was in good agreement with obtained by photometry with 2,2´-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid (ABTS). The developed approach can be beneficial for the quantification of L-DOPA using a BDD electrode as up-to-date potential alternative sensor for electroanalytical applications.