Highly-sensitive detection of eight typical fluoroquinolone antibiotics by capillary electrophoresis-mass spectroscopy coupled with immunoaffinity extraction

Fluoroquinolones (FQs) are a class of synthetic antibiotics with a broad active spectrum towards mycoplasma and bacteria (both Gram positive and negative). The contamination of environmental water samples with FQs has been a concern due to the extensive use of them in the veterinary and pharmaceutical industries. Reliable and simple analytical methods are needed for the monitoring of these FQs. An off-line procedure of immunoaffinity extraction (IAE) followed by capillary electrophoresis-mass spectroscopy (CE-MS) has been developed for simultaneous determination of eight typical FQs in environment water. A broad-specific polyclonal antibody was home-prepared and immobilized on a Sepharose 4B stationary phase for sample affinity extraction and the enrichment factor of our columns was about 100. CE-MS was subsequently applied to FQs separation and quantification. The immunoaffinity column was evaluated in the parameters of selectivity, binding capacity, elution protocol, and recovery. Under the optimized conditions, the developed method was successfully applied to analyze FQs spiked with 2.5 nM to 30 nM of environmental water from a local lake, providing satisfactory recoveries from 72% to 112%, and LODs and LOQs ranging from 1.2 nM to 5.0 nM and 4.0 nM to 17 nM, respectively.