Dispersive liquid–liquid microextraction combined with field-amplified sample stacking in capillary electrophoresis for the determination of non-steroidal anti-inflammatory drugs in milk and dairy products

Dispersive liquid–liquid microextraction (DLLME) was coupled with field-amplified sample stacking in capillary electrophoresis (FASS) for the determination of five non-steroidal anti-inflammatory drugs (NSAIDs) in bovine milk and dairy products. After extraction, the enriched analytes were back-extracted into a basic aqueous solution for injection into CE. Under optimum conditions, enrichment factors were in the range 46–229. Limits of detection of the analytes ranged from 3.0 to 13.1 μg kg−1 for all matrices analysed. Calibration graphs showed good linearity with coefficients of determination (R2) ⩾ 0.9915 and relative standard deviations (RSD%) of the analyses in the range of 0.6–6.2% (n = 5). Recoveries of all NSAIDs from bottled milk, raw milk, yogurt and white cheese samples were in the ranges of 86.6–109.3%, 84.3–100.5%, 77.4–107.3%, and 90.9–101.6%, respectively. DLLME–FASS-CE was demonstrated to be a rapid and convenient method for the determination of NSAIDs in milk and dairy products.