Ali A. Ensafi, M. Gorgabi-Khorzoughi, B. Rezaei, M. Jafari-Asl,

In the present study, an efficient electrocatalyst was developed for simultaneous determination of gua- nine and adenine. The method is based on the synergetic effect of polyoxometalate ([PW11NiO39] 5 −) modified poly diallyl dimethyl ammonium chloride at multiwall carbon nanotube (MWCNTs) on the ox- idation of guanine and adenine. The characteristics of the fabricated nanocomposite were studied using different techniques including spectroscopic techniques, Brunauer–Emmett–Teller surface area analysis, and electrochemical methods. The influence of experimental and chemical parameters on the sensitiv- ity was studied. Calibration curves were obtained under the optimum conditions for the determination of adenine and guanine with linear ranges of 0.4–136.0 and 0.4–76.0 μmol L −1 and with detection limits of 0.24 and 0.1 μmol L −1 , respectively. The modified electrode showed excellent repeatability and repro- ducibility. The designed electrochemical sensor has been used successfully for the determination of these two compounds in ssDNA salmon sperm sample.