A glassy carbon electrode modified with carboxylated diamond nanoparticles for differential pulse voltammetric simultaneous determination of guanine and adenine

The authors describe a differential pulse voltammetric technique for the simultaneous determination of guanine (Gu) and adenine (Ad). A glassy carbon electrode (GCE) was modified with a chitosan film containing functionalized diamond nanoparticles (f-DNPs/CS) of 1020 nm average size. The materials were characterized by field emission scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and the modified electrode was characterized by cyclic voltammetry and differential pulse voltammetry. The modified glassy carbon electrode (f-DNPs/CS/GCE) is shown to display high electrocatalytic activity toward the oxidation and determination of Gu and Ad, respectively, with oxidation peaks that are strongest at 0.72 +/- 0.02 V for Gu and at 1.02 +/- 0.02 V for Ad (both versus Ag/AgCl). Responses in differential pulse voltammetry are linear to Gu in the 0.05-30.0 mu M concentration range, and to Ad in the 0.1-14.0 mu M concentration range, and the detection limits (at an S/N ratio of 3) are 2 nM and 10 nM for Gu and Ad, respectively. The f-DNPs/CS/GCE was successfully applied to the simultaneous determination of Gu and Ad in fish sperm DNA and typically gave 97.5 and 98.8 % recoveries.