Tea quality testing using 6B pencil lead as an electrochemical sensor

NANDIMALLA VISHNU, Mansi Gandhi, Sushmee Badhulika, Annamalai Senthil Kumar

Index: 10.1039/C8AY00557E

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Abstract

Isomers of dihydroxy benzene (DHB) like 1,2-DHB, 1,3-DHB and 1,2,3-trihydroxy benzene (1,2,3-THB) are the functional constituent of tea polyphenols. Herein, we report an elegant 6B pencil lead for the real-time tea quality assessment via a simple and quick procedure to electrochemically detect the polyphenols in a mixture without and adsorption complication. A pre-anodised 6B-PGE, denoted as 6B-PGE* has showed well-defined anodic signals without any separation technique for the dihydroxy (DHB) and trihydroxy benzene derivatives present in the tea polyphenols at distinct potentials. Differential pulse voltammetry was adopted for the quantification procedure. Constructed calibration plots were linear in a window, 10-100 uM, 50-350 uM and 10-70 uM for 1,2-, 1,3- and 1,4-DHB isomeric derivatives, respectively. Calculated sensitivity and detection limit (signal-to-noise ratio = 3) values were 0.2234, 0.0725 and 0.0627 uA uM-1 and 0.719, 2.469 and 5.072 uM, respectively. Quantification of polyphenolic content in two different tea dust samples were demonstrated as representative examples.