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

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 mu L of N,N-dimethylcy-clohexylamine as the extraction solvent and 750 mu L of 10.0 M sodium hydroxide as the phase separation trigger. Optimum DSPME were sample pH at 6.0, 1000 mu L of acetone as the eluent, 30.0 mL of sample, 12.5 mg of Fe 3 0 4 @XAD-16 as the adsorbent, 4.0 and 1.5 min as the adsorption and elution times, respectively. Calibration graphs with coefficient of determination (R-2) 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.

Automated summary

The combination of switchable-hydrophilicity solvent-liquid-liquid microextraction (SHS-LLME) and dispersive solid-phase microextraction (DSPME) showed efficient preconcentration and determination of quercetin, with high recovery rates and good repeatability. The proposed method is superior in terms of greenness, rapidness, simplicity, and low capital cost, making it a promising technique for sample cleanup and analysis.