Electrocatalytic oxidation of D-penicillamine (D-PA) at the surface of ferrocene modified carbon paste electrode (FCCPE) was thoroughly investigated in aqueous solution with various pH. The performance of this modified electrode was compared with those of 2,7-bis(ferrocenyl ethyl) fluoren-9-one modified carbon paste electrode (2,7-BFEFMCPE). In the optimum condition, the oxidation of D-PA at the surface of FCCPE and 2,7-BFEFMCPE is occurred about 480 and 320 mV less positive than that unmodified carbon paste electrode, respectively. The linear dynamic ranges 6 ×10–5 M–2 ×10–3 M, 6⋅5 ×10–5 M–1⋅1 ×10–3 M and 7 ×10–6 M–1⋅6 ×10–4 M, 7 ×10–6 M–2 ×10–4 M of D-PA are obtained from CV and DPV methods for FCCPE and 2,7-BFEFMCPE, respectively. The detection limits (3σ) were determined as 5⋅4 ×10–5 M and 6⋅3 ×10–5 M in CV and 6⋅2 ×10–6 M and 6⋅8 ×10–6 M in DPV determinations for FCCPE and 2,7-BFEFMCPE, respectively. The proposed method was applied in a highly sensitive determination of D-PA in drug and human synthetic serum samples by standard addition and recovery methods, respectively. Brilliant cresyl blue, Carbon paste electrode. Differential pulse voltammetry. DNA biosensor, Electroactive label
