Sensitive analysis of antibiotics via hyphenation of field-amplified sample stacking with reversed-field stacking in microchip micellar electrokinetic chromatography

An on-chip multiple-concentration method combining field-amplified sample stacking (FASS) and reversed-field stacking (RFS) in microchip micellar electrokinetic chromatography (MCMEKC) was developed for the simultaneous analysis of three antibiotics (kanamycin, vancomycin, and gentamycin) using poly (styrene sulfonic acid) sodium salt (PSS) as the pseudostationary phase. Results indicated that the polymeric surfactant PSS provided high stability, unique selectivity, and high efficiency for the separation of these antibiotics as compared to SDS micelles, and the multiple-preconcentration strategy could greatly improve the sensitivity enhancement over those classical CE-LIF methods for antibiotics detection. The stacking and separation mechanism as well as important parameters governing preconcentration and separation have been investigated in order to obtain maximum resolution and sensitivity. Under optimal conditions, three antibiotics were successfully focused and completely separated within <3. min. The limits of detection for kanamycin, vancomycin, and gentamycin were 0.25, 0.20, and 0.80. μg/L (S/N = 3), respectively, and the detection sensitivities were improved 259-, 296-, and 308-fold, respectively. The method also gave accurate and reliable results in the analysis of these antibiotics in river water samples.