Fig. 4. Baseline-corrected square-wave voltammetric responses (vs. Ag/AgCl) of street samples at bare carbon screen-printed electrodes in 0.1 M KCl + 0.020 M KH2PO4 buffer solution (pH 7). The dotted line represents the characteristic oxidation potential of cocaine at 1.04 V. The y-axis has the same scale in every voltammogram. Each solution was prepared in such way that it contains 1 mM of cocaine.
