Determination of 11 quinolones in bovine milk using immunoaffinity stir bar sorptive microextraction and liquid chromatography with fluorescence detection

• Quantification of 11 QNs in bovine milk.
• Monoclonal antibody to QNs was immobilized to glass bar.
• An immunoaffinity SBSME-LC-FLD method was firstly developed and validated.
• Different conditions during sample preparation were optimized.
• The column capacity and stability of immunoaffinity sitr bar was investigated.

A sensitive, selective and reproducible immunoaffinity stir bar sorptive microextraction (SBSME) coupled with liquid chromatography-fluorescence method for determination of 11 quinolones (QNs) in bovine milk was developed and validated. It is first report of a broad-specificity monoclonal antibody to QNs that has been immobilized to glass bar for preparation of a re-usable immunoaffinity stir bar. Analytes were extracted by placing stir bar in milk and shaking on a rotary shaker for 30 min at 30 rpm, followed by liquid chromatography and fluorescence detection. The newly developed method has limits of detection for each QN from 0.05 to 0.1 ng/g with intra-day and inter-day precision ranging from 3.2 to 11.9% and from 5.2 to 12.5%, respectively. This allowed us to quantitatively analyze drugs in bovine milk with the advantage of significantly simplified sample preparation. The proposed method was successfully applied to the bovine milk samples analyses with QNs, demonstrating its rare application in animal food safety analysis.