Analysis of cephalosporin residues in environmental waters by capillary zone electrophoresis with off-line and on-line preconcentration

Abstract

A sensitive and reliable method using capillary zone electrophoresis with UV-diode array detection (CZE-DAD) has been developed and validated for trace determination of cephalosporin antibiotics in spring water, groundwater and river water matrices. Due to the lack of sensitivity of the UV-Vis detection method, a solid-phase extraction (SPE) method has been applied for off-line preconcentration and cleanup of water samples, in combination with an on-line preconcentration methodology named large volume sample stacking (LVSS) with polarity switching. The simultaneous determination of five cephalosporins of veterinary use, namely cephalexin (CFL), cephoperazone (CFPR), ceftiofur (CFTF), cephapirin (CFP) and cephazolin (CFZ) has been accomplished in environmental water samples using 70 mM acetate buffer, pH 7.0, applying a voltage of 22.5 kV at 25 °C and using cephadroxil (a cephalosporin for human use) as the internal standard. For the SPE procedure a HLB sorbent column was used. The combination of both off-line and on-line preconcentration procedures provided a significant improvement in sensitivity, obtaining detection limits of 0.1 μg L⁻¹ for CFL; 0.2 μg L⁻¹ for CFPR, CFTF and CFP, and 0.3 μg L⁻¹ for CFZ. The SPE-LVSS-CZE-DAD procedure is suitable for monitoring these compounds in water samples with high sensitivity and precision and satisfactory recoveries.