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 ?mol/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 ??? 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 ?g/g; the analytes were separated in less than 6 min. The methodology proposed is useful for controlling and monitoring antibiotic residues in feedstuff samples.