Microextraction of ampicillin from bovine milk using ionic liquids and deep eutectic solvents prior to its chromatographic determination with ultraviolet and tandem mass spectrometry detection

Abstract

Liquid-liquid microextraction procedures using ionic liquid (IL) and deep eutectic solvent (DES) as the new extractants for isolation of β-lactam antibiotic ampicillin (AMP) from milk samples were developed. In this purpose IL: 1-butyl-3-methylimidazolium hexafluorophosphate and DES: choline chloride-thymol (1:2) were used as the extraction medium. These green solvents are characterized by favorable solvating properties for a range of compounds. Ionic liquid was used as extractant in dispersive liquid-liquid microextraction (DLLME) connected with acetonitrile as disperser solvent while deep eutectic solvent was applied for liquid-liquid microextraction (LLME). The isolation parameters of ampicillin, namely, amount of extraction solvents, pH of milk sample, shaking and centrifugation time were optimized. The extracts were analyzed followed by liquid chromatographic method with ultraviolet (HPLC-UV) and tandem mass spectrometry (LC-MS/MS) system for DLLME and LLME isolation procedures, respectively. The calibration curves were linear in the analyte concentration range of 1 . 10−7 mol L−1 (36.1 µg kg−1) – 1 . 10−4 mol L−1 (36127.0 µg kg−1) for IL-DLLME-HPLC-UV technique and 1 . 10−8 mol L−1 (3.6 µg kg−1) – 1 . 10−4 mol L−1 (36127.0 µg kg−1) for DES-LLME-LC-MS/MS method. The elaborated procedures were applied for the determination of ampicillin in the different milk samples.