Nanomolar detection of chlorogenic acid at the cross-section surface of the pencil lead electrode

The detection of chlorogenic acid in clinic samples for metabolic kinetics study is quite a challenging task due to the low concentration and the lacking of sensitive quantitation methods. In this work, a porous pencil lead electrode (PLE) has been used to detect chlorogenic acid by square wave voltammetry (SWV) technique. The redox potential of chlorogenic acid is at ca. + 0.42V (pH = 3.0) versus saturated calomel electrode (SCE), and it's a reversible thin layer electrochemical process with two-electrons and two-protons involved in this reaction. The sensitivity was significantly improved due to the enrichment of CGA at the porous structure of the electrode. Under the optimized conditions, the concentration of chlorogenic acid was linear in the range of 7.7 x 10(-8) similar to 7.7 x 10(-6) M with detection limits down to 4.5 x 10(-9) M (R-2 = 0.9978, S/N = 3). The electrode was successfully used for the determination of chlorogenic acid in human urine with near 100 % recovery. Due to the advantages of simplicity of fabrication, high sensitivity, good reproducibility and easy renewability, we believe that the porous PLE is quite a promising candidate for determination of chlorogenic acid in clinic samples.