Optimization of a rapid and sensitive ultrasound-assisted liquid-liquid microextraction using switchable hydrophilicity solvent for extraction of β-carotene in fruit juices and vegetables

A simple, rapid and sensitive ultrasound-assisted liquid-liquid microextraction by switchable hydrophilicity solvent (UA-LLME-SHS) method was developed first time for extraction and determination of β-carotene from fruit juices and vegetables using a spectrophotometer. The effect of pH, solvent dose, ultrasound time, volume of NH₄OH, volume of NaCl (w/v) and effects of different chemicals on extraction recovery was investigated. The proposed method showed good extraction recovery of β-carotene. The working range of the developed method was 50–700 ng mL⁻¹. Limits of detection and quantification were 15.5 μg L^-1 and 50 μg L^-1, respectively. The intraday and interday precisions of the developed method was investigated for 75 ng mL⁻¹ and 400 ng mL⁻¹ of β-carotene. As a result of the study, the relative standard deviation values were in the range of 2.8–3.3 % and 3.0–4.2 % for the intraday and interday studies, respectively. The enhancement factor was 114 and extraction recovery of β-carotene was found 98.3 %. The factorial design was drawn to know the combined effects of variables and their significant and insignificant effects on the determination of the β-carotene.