In this study, new amperometric dot microsensors based on graphene and phthalocyanines: basic phtalocyanine, Fe(III)phthalocyanine and Co(II)phthalocyanine are proposed for the assay of adenine, guanine and epinephrine in real biological fluids (e.g. urine samples), using differential pulse voltammetry (DPV). Cyclic voltammetry (CV) was used to optimize the working conditions, e.g., pH, and electrolyte for the proposed dot microsensors obtaining an optimum of 0.1 mol L-1 KCl or 0.1 mol L-1 KNO3 in a phosphate buffer solution at a pH = 4.0. The lowest limits of detection obtained for adenine (2.5 x 10(-6) mol L-1), guanine (1.4 x 10(-5) mol L-1), and epinephrine (1 x 10(-6) mol L-1), as well as the selectivity coefficients made possible their assay in urine samples with high reliability (RSD < 1.0%). Adenine, guanine and epinephrine were recovered reliably from urine samples in percentages higher than 90.00%. (C) 2013 The Electrochemical Society. All rights reserved.