“…Several methods have been developed for this purpose including colorimetry, chromatography, chemiluminescence and spectrophotometry (Varanka et al 2001;Xie & Cui 2003;Naczk & Shahidi 2004;Pelozo et al 2008). Compared with those methods above, electrochemical techniques for tannic acid determination have some advantages such as: high sensitivity, accuracy, simplicity and low expense (Lu 2004;Xu et al 2009;Raj et al 2013;Vu et al 2013). Among carbon based electrodes, pencil graphite electrodes (PGEs) have some advantages such as commercial availability with low cost, good mechanical rigidity, disposability, renewability, and ease of modification.…”