Matrix solid-phase dispersion extraction of carbadox and olaquindox in feed followed by hydrophilic interaction ultra-high-pressure liquid chromatographic analysis

A new method involving matrix solid-phase dispersion (MSPD) extraction and hydrophilic interaction ultra-high-pressure liquid chromatography (HILIC-UHPLC) with photodiode array detection was developed for the determination of carbadox and olaquindox in feed. Separation of carbadox and olaquindox was achieved within 1 min on the 1.7 mu m Acquity UPLC BEH HILIC column by using isocratic elution with a mobile phase consisting of 10 mmol L-1 ammonium acetate in acetonitrile-water(95:5,v/v) at a flow rate of 0.5mLmin-1. Optimization of MSPD extraction parameters, such as type of solid sorbent and elution solvent were carried out. Optimal conditions selected for MSPD extraction were: 0.25 g of feed sample, 0.5 g of octaclecylsilica as solid sorbent and 10 ml. of acetonitrile-methanol (8:2, v/v) as eluting solvent. Both analytes provided average recoveries from spiked feed samples ranging from 89.1 to 98.4% with relative standard deviations less than 10%. Obtained performance characteristics are comparable to those achieved by liquid-liquid extraction-HPLC with the advantages of being simpler and significantly faster. (C) 2008 Elsevier B.V. All rights reserved.