In vitro Determination of Guanine, Adenine and Thymine Using a New Schiff base Transition Metal Complex as a Sensing Platform

A novel chemically modified carbon paste electrode based on an inexpensive Ni(salph) complex, where salph is N , N' -bis(salicylidene)-4-methyl- o -phenylenediimine, was prepared for the simultaneous determination of guanine, adenine and thymine. The electrode was characterized by Fourier-transform infrared spectroscopy, field emission scanning electron microscopy, X-ray diffraction, energy dispersive X-ray analysis, thermogravimetric analysis and cyclic voltammetry. The proposed sensor enhanced the anodic peak currents of the nucleobases and could determine them sensitively in 0.1 M phosphate buffer solution (pH 7.0). Moreover, well-separated voltammetric peaks were obtained for guanine, adenine and thymine present in the analyte mixture. Under the optimum operating conditions, the peak currents for guanine, adenine and thymine increased linearly with the increase in the analyte mixture concentration in the ranges of 0.1 to 80, 0.1 to 50 and 15 to 150 μM, respectively. The detection limits for guanine, adenine and thymine were 0.03, 0.03 and 5 μM, respectively. This new approach has been successfully applied for the detection of the corresponding targets in a DNA sample with acceptable recovery.