Ionic liquid dispersive liquid–liquid microextraction combined with high performance liquid chromatography for determination of tetracycline drugs in eggs

Abstract

Ionic liquids are used more and more as a class of novel extraction solvents to extract various compounds from simple and complex samples. The objective of this study was to develop an ionic liquid-based dispersive liquid–liquid microextraction procedure combined with high performance liquid chromatography for determination of tetracycline drugs in eggs. Ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate was proven to show the best performance among the four tested ionic liquids. Several parameters possibly influencing the extraction efficiency (ionic liquid and its volume, disperser solvent and its volume, extraction and centrifuge time, pH and salt addition) were investigated and optimized. Under the optimal conditions, this method showed different enrichment factors (12–44 fold) for four tetracycline drugs (tetracycline, oxytetracycline, doxycycline and chlortetracycline). The limits of detection for the four analytes in eggs were in the range of 2.0–12 ng g⁻¹ and the recoveries from the standard fortified blank egg were in the range of 58.6–95.3% with coefficients of variation lower than 6.2%. Therefore, this method can be used as a simple and sensitive tool to determine the residues of the four tetracycline drugs in eggs.