Screening and authentication of tea varieties based on microextraction-assisted voltammetry of microparticles

• Different tea varieties were characterized using voltammetry of microparticles.
• Significant differences were found between the voltammetric patterns of green, oolong and black teas.
• Bivariate and multivariate chemometric methods discriminate green, oolong and black teas in mixtures.

A simple electrochemical methodology for screening and authentication of green, black and red tea varieties is proposed. It is based on the record of the voltammetric response of microparticulate films of antioxidant compounds resulting from an ethanolic micro-extraction of commercial tea herbal preparations in contact with aqueous buffers. The obtained voltammetric responses led us to differentiate between diverse tea varieties upon application of bivariant and multivariant chemometric techniques, including discrimination of mixtures of teas with sensitivity estimated of 5.0 μA mg−1 with a detection limit of 0.01 mg of tea sample. Under the proposed conditions 100% discrimination rate was achieved for binary mixtures of teas between 10:1 and 1:10 w/w composition.

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