Electrochemical Determination of Penicillin G in Cow Milk and pharmaceuticals in SDS/Acetate buffer
Joshua M. Sila, Peterson M. Guto, Immaculate Michira, Francis Mwaura, Edward K. Muge
Abstract
Penicillin residues in animal food products like milk and meat has attracted great concern by health regulatory agencies due to their negative effects. Therefore, there is urgent need for reliable, low cost, fast and simple analytical tools/methods to monitor these penicillin residues in animal products before distribution to consumers. In our previous work, we developed a square wave voltammetric method based on bare glassy carbon electrode in SDS/ABS media to determine penicillin V and G. In this work, we apply this voltammetric method to detect penicillin G at trace levels in cow milk and selected pharmaceutical samples. Using cyclic voltammetry, the electrochemical behavior of penicillin G in both cow milk and pharmaceutical samples were obtained. The oxidation potentials were 1.65V in both samples, same as that obtained in SDS/ABS media. The diffusion coefficients were 1.494x10 -6 cm 2 /sec in cow milk, 2.358x10 -7 cm 2 /sec in pharmaceutical sample and 1.392x10 -6 cm 2 /sec in SDS/ABS media. The precision for the detection of the drug was also determined and recorded as relative standard deviation (RSD). The RSD found were 4.22% and 5.51% for cow milk and pharmaceutical sample respectively. The percent recoveries for accuracy determination were found to lie between 95.8% - 103.0% for the cow milk and 92.0% - 96.0% for the pharmaceutical samples. These recovery percentages were within the recommended 90.0% - 110.0%. A detection limit of 2.5×10 3 ng/L penicillin G was achieved in cow milk samples against a maximum residue limit of 4.0×10 3 ng/L set by the European Union. Overly, this method provides simple, precise and consistent results for detection and quantification of penicillin G in cow milk, pharmaceuticals and possibly other environmental and clinical samples.