Voltammetric determination of harmaline in natural food products using boron-doped diamond electrode

Abstract A novel analytical approach for the sensitive determination of a β -carboline alkaloid, harmaline, was developed using pulse voltammetric techniques with a boron-doped diamond electrode. Cyclic voltammetry showed two irreversible oxidation peaks at about +0.90 and +1.20 V (vs. Ag/AgCl) in Britton–Robinson buffer solution at pH 5. Under optimized experimental conditions, differential pulse and square-wave voltammetry were elaborated for the determination of harmaline in a linear concentration range from 0.2 to 100.7 and from 0.4 to 104.5 μmol L −1 , respectively, with detection limits of 0.08 and 0.2 μmol L −1 , respectively. The practical feasibility of the developed method was demonstrated by quantification of harmaline in the extracts of natural food products such as Syrian rue ( Peganum harmala , also known as esphant , harmal , yuzerlik ) seeds, locally used as condiment and medicine in Turkey and the Near and Middle East, and the South American shamanic drink component Ayahuasca liane ( Banisteriopsis caapi ) with results in good agreement with those obtained by high-performance liquid chromatography as a reference method. The proposed sensor represents an effective electrochemical tool and inexpensive alternative for quality control analysis of food products containing harmaline.