Adenine (A) and guanine (G), important bases of nucleic acids, are often analyzed by separation coupled spectroscopic detection methods. Herein, we are demonstrated a new flow-injection analysis (FIA) coupled dual electrochemical detector (DECD), where a chitosan-carbon nanofiber (Chit-CNF) modified glassy carbon electrode prepared by a simple technique and pH 7 phosphate buffer solution as a carrier system, for separation-less quantification of G and A. This method is highly selective and no interference by the presence of the other DNA bases (Thymine and Cytosine). The FIA-DECD was operated at two different operating potentials, E1 = 0.80 V and E2 = 0.95 V vs Ag/AgCl, where G and {G + A} get oxidized, respectively. Amount of A was calculated from the difference between the FIA current signals, measured at E20.95V and E1 0.80V. The GCE/Chit-CNF was characterized by cyclic voltammetry with potassium ferricyanide system and Raman spectroscopy. The modified electrode showed unique electron-transfer feature with metal like conductivity. Under an optimal condition, FIA-DECD showed linear calibration plots for G and A in a concentration range, 200 nM - 50 μM with current sensitivity values 13.83 ± 0.48 and 4.84 ± 0.11 nA μM-1 respectively. Calculated detection limit (signal-to-noise ratio = 3) values were 46.8 nM and 73.8 nM for G and A respectively. Applicability of the present technique was further demonstrated by detecting G and A in beef kidney sample and DNA hybridization process. © 2014 Elsevier Ltd.