Preparation of Activated Disposable Pencil Graphite Electrode for the Selective and Sensitive Determination of a Fluoroquinolone Antibiotic: Levofloxacin

Abstract

Background: Levofloxacin (LVX) is one of the fluoroquinolone antibiotics that possess a wide spectrum of bactericidal activity against both Gram-positive and Gram-negative bacteria. Because of its side effects and its potential towards the development of antibiotic resistance, determination of this antibiotic is very important. New methods which have superior properties than the conventional methods are needed in the determination of pharmaceuticals in different samples. Method: An activated pencil graphite electrode (A-PGE) was prepared and its application in the voltammetric determination of LVX in pharmaceutical samples and body fluids was searched. Results: Oxidation peak currents of LVX were increased 40 times in the presence of A-PGE according to bare PGE. The highest voltammetric response of A-PGE towards LVX was achieved at pH value of 4. A wide linear range (0.01 – 2.5 µM) was observed between the oxidation peak currents and concentrations of LVX. Detection limit was calculated as 0.0075 µM. The inter-day (five days) precision of APGE was found to be 3.16%. Interference studies showed that A-PGE successfully discriminated the voltammetric response of LVX from that of many other structurally related substances such as ciprofloxacin, norfloxacin and enoxacin. Prepared A-PGE preserved 87% of its original activity towards LVX after a 2-month storage. Determination of LVX in blood serum, urine and pharmaceuticals was successfully achieved by A-PGE. Conclusion: The prepared A-PGE brings two important advantages. First one is the selective response of A-PGE towards LVX in the presence of other fluoroquinolone antibiotics (ciprofloxacin, enoxacin and norfloxacin). The other is the high sensitivity of A-PGE towards LVX having the detection limit of 0.0075 µM. In addition to the given advantages, its disposable character, low cost, commercial availability and easy preparation of A-PGE make this electrode an important candidate in the fast and accurate determination of LVX. Keywords: Levofloxacin, pencil graphite, voltammetry, electrochemical overoxidation, electrode, fluoroquinolone.