OXYTETRACYCLINE ELECTROCHEMICAL DETERMINATION AT DISPOSABLE PENCIL GRAPHITE ELECTRODE

Oxytetracycline (OTC) is a broad-spectrum antibiotic that belongs to the tetracycline class. It is utilized in both human and veterinary medicine to treat a variety of bacterial infections and as a feed additive for animals. Therefore, there is an increased need in the development of simple, rapid and reliable methods for this antibiotic determination in various matrices. This work presents OTC voltammetric analysis at the disposable, cheap pencil graphite electrode (PGE). The voltammetric response was investigated at different types of working electrodes emphasized that the highest sensitivity was exhibited by PGE using HB type pencil leads. Electrochemical pretreatment of the PGE did not bring any improvement in OTC oxidation signal. The effect of solution pH on the voltammetric behavior of OTC was examined using both cyclic voltammetry (CV) and differential pulse voltammetry (DPV) in Britton-Robinson Buffer (BRB) solutions with pH values ranging from 2.00 to 11.00. The oxidation was irreversible, resulting a diffusion- controlled process that was dependent on pH and involved an equal number of electrons and protons. The highest signal was observed at pH 4.56. Applying DPV on HB PGE, the oxidation peak of the analyte increased linearly with its concentration in the range 1.00 x 10-6 to 3.60 x 10-4 mol/L. The method's limit of detection was calculated to be 6.80 x 10-7 mol /L OTC. The applicability of the developed DPV method using HB PGE was tested by quantification the antibiotic from veterinary pharmaceutical preparations. Employing the standard addition method, the obtained mean recovery was 103.12%.