DETERMINATION OF NANOMOLAR LEVELS OF GUANINE BY DIFFERENTIAL-PULSE ADSORPTIVE CATHODIC STRIPPING VOLTAMMETRY OF ITS COPPER(II) COMPLEX

Guanine is determined at the 5.0 X 10(-10) -2.0 X 10(-7) mol/l level b y differential-pulse adsorptive stripping voltammetry at a hanging mer cury drop electrode using the reduction peak of its copper (II) comple x at -0.21 V vs. Ag-AgCl electrode. The optimum analytical conditions were found to be Britton-Robinson buffer solution (pH 4.8), an accumul ation potential of 0.0 V and an accumulation time of 3 min. Under thes e conditions, the detection limit is 5.0 X 10(-10) mol/l and the relat ive standard deviation 2.6% for 1.0 X 10(-7) mol/l guanine. The method is compared with the previous voltammetric methods. The presence of s ome purine derivatives does not interfere.