Determination of six veterinary pharmaceuticals in egg by liquid chromatography: Chemometric optimization of a novel air assisted-dispersive liquid-liquid microextraction by solid floating organic drop.

Two extraction strategies for albendazole, chloramphenicol, trimethoprim, enrofloxacin, oxitetracycline and nicarbazin in egg were optimized for its quantitation by liquid chromatography. First, two designs were built to find out the optimized condition for the air assisted-dispersive liquid-liquid microextraction based on solidification of organic drop: a fractional factorial and a central composite design. The optimum conditions were 1140µL of water, 125mg of ZnSO4, 1175µL of acetonitrile, 1200µL of methyl alcohol and 740µL of propanone, using 1.00g of homogenized egg and 50µL of 1-dodecanol. Second, two designs were also built to optimize the dispersive liquid-liquid microextraction: a central composite design and a mixture design to set the combination of the re-suspended solvents. The optimum conditions were 1840µL of acetonitrile and 160µL of dichloromethane and the re-suspended mixture consisting in acetonitrile and sodium phosphate buffer 10mmolL-1 pH = 3.50 (30:70v/v).