Switchable-hydrophilicity solvent liquid-liquid microextraction for sample cleanup prior to dispersive magnetic solid-phase microextraction for spectrophotometric determination of quercetin in food samples

Abstract

Switchable-hydrophilicity solvent-liquid-liquid microextraction (SHS-LLME), as an efficient sample cleanup method, was combined with dispersive solid-phase microextraction (DSPME) for preconcentration of quercetin prior to its spectrophotometric determination. Optimum SHS-LLME were found as 1000 μL of N,N-dimethylcyclohexylamine as the extraction solvent and 750 μL of 10.0 M sodium hydroxide as the phase separation trigger. Optimum DSPME were sample pH at 6.0, 1000 μL of acetone as the eluent, 30.0 mL of sample, 12.5 mg of Fe3O4@XAD-16 as the adsorbent, 4.0 and 1.5 min as the adsorption and elution times, respectively. Calibration graphs with coefficient of determination (R2) higher than 0.9956, limits of detection (LOD) of 9.0–11.9 ng mL−1 and limits of quantitation (LOQ) of 29.9–39.6 ng mL−1 were obtained. Repeatability, expressed as percentage relative standard deviation (%RSD), was better than 3.2 and 8.9% for intra- and inter-day precision, respectively. The proposed SHS-LLME-DSPME-UV/Vis method was applied for the determination of quercetin in four food samples (i.e., apple, pepper, red and white onion) with percentage recoveries in the range of 92.1–107.4%. The proposed method is superior to others in terms of greenness, rapidness, simplicity, good repeatability and low capital cost.