Determination of antibiotics in feedstuff samples by microemulsion electrokinetic chromatography using fullerene as additive

A microemulsion electrokinetic chromatography method was developed for the simultaneous detection and quantification of ciprofloxacin, norfloxacin, sulfamethoxazole, tetracycline, and oxytetracycline in feedstuff samples. The BGE composition was optimized by applying a Taguchi parameter design and consisted of phosphate 30 mmol/L, Tween-80 0.01 mmol/L, and fullerene 3 μmol/L, and adjusted to pH 8.0; the addition of surfactant and fullerene modifies the mobility of the analytes improving their resolution. Theoretical studies showed π-π and van der Waals interactions between antibiotic molecules and fullerene used as a pseudostationary phase. Under optimal conditions, limits of detection ranged from 0.7 to 1.5 μg/g; the analytes were separated in less than 6 min. The methodology proposed is useful for controlling and monitoring antibiotic residues in feedstuff samples.