Voltammetric determination of penicillin V in pharmaceutical formulations and human urine using a boron-doped diamond electrode

Simple, sensitive and selective differential pulse voltammetric method for determination of penicillin V on a bare (unmodified) boron-doped diamond electrode has been developed. Penicillin V provided highly reproducible and well-defined irreversible oxidation peak at very positive potential of + 1.6 V (vs. Ag/AgCl). The optimum experimental conditions for oxidation of penicillin V were achieved in acetate buffer solution (pH 4.0). The modulation amplitude of 0.1 V, modulation time of 0.05 s and scan rate of 0.05 V s− 1 were selected as optimum instrumental parameters for differential pulse voltammetry. Linear response of peak current on the concentration in the range from 0.5 to 40 μM with coefficient of determination of 0.999, good repeatability (RSD of 1.5%) and detection limit of 0.25 μM were observed without any chemical modifications and electrochemical surface pretreatment. The effect of possible interferents such as stearic acid, glucose, urea, uric acid and ascorbic acid appeared to be negligible which evidently proved the good selectivity of method. The practical analytical utility of proposed method was demonstrated by determination of penicillin V in pharmaceutical formulations (tablets) and human urine samples with satisfactory recoveries (from 98 to 101% for tablets and 97 to 103% for human urine).

► Unmodified BDD electrode = sensitive electrochemical sensor for drug determination.
► No special pretreatment of samples except simple dilution.
► Selective method, common compounds present in urine don't interfere in high excess.
► BDD electrode = recommended drug sensor in doping test in competitive games.