The polarographic and voltammetric behaviour of DNA (deoxyribonucleic acid) has been studied .A well defined linear sweep voltammetric peak is obtained at -1.65V( vs .Ag/AgCl) in 0.1mol·L -1 NH 4Cl.The peak current is proportional to the concentration of DNA over the range of 4.5×10 -5 ~3 7×10 -4 mol·L -1 ,which can be applied to the determination of DNA.It is proposed that the reactant is the strand scission DNA of duplex scission (natural) DNA with four exchanged electrons and the el...