Spectrofluorimetric determination of cefixime using terbium-danofloxacin probe

Cefixime (Cfx), is a semi-synthetic third-generation oral cephalosporin antibiotic that is prescribed for the treatment of susceptible infections. There are some procedures for the determination of Cfx in pharmaceutical formulations and biological samples. Herein a spectrofluorimetric method was proposed for Cfx determination based on the fluorescence quenching of terbium-danofloxacin (Tb(3+)-Dano) in the presence of Cfx.

Cfx was detected based on fluorescence quenching of terbium-danofloxacin (Tb(3+)-Dano) in the presence of Cfx with maximum excitation and emission wavelengths at 347 nm and 545 nm, respectively. The quenched fluorescence intensity of Tb(3+)- Dano system is proportional to the concentration of Cfx. The optimum conditions for the determination of Cfx were studied.

The maximum response was achieved under optimum conditions of [Tris buffer]= 0.008 mol/l (pH 6.5), [Tb(3+)]=1×10(-4) mol/l and [Dano]=1×10(-4) mol/l. The developed method was evaluated in terms of accuracy, precision and limit of detection. The linear concentration ranges for quantification of Cfx were 8.8×10(-8)-8.8×10(-7) mol/l and 1.1×10(-7)-8.8×10(-7) mol/l in standard and human serum samples with the detection limits (S/N=3) of 2.8×10(-8) mol/l and 3.9×10(-8) mol/l, respectively. The Cfx was determined in pharmaceutical tablets and spiked serum samples and the results were satisfactory.

This method is simple, practical and relatively interference-free for determination of Cfx in pharmaceutical tablets and serum samples.