Development of a dispersive liquid-liquid microextraction method based on solidification of a floating organic drop for the determination of beta-carotene in human serum

A dispersive liquid-liquid microextraction method based on solidification of a floating organic drop (DLLME-SFO) was developed for HPLC determination of β-carotene in human serum. A narrow-neck glass tube was used for simple and rapid collection of the solidified organic phase from aqueous surface after its centrifugation and cooling in a water bath. Acetone and 2-decanol were used as the disperser and organic phases, respectively. Effects of salt concentration and phase volumes on the extraction of the analyte were optimized using a central composite design method. During the optimization, a spectrophotometric method was used for determinations. Under the optimized conditions, an extraction recovery of 99.0 ± 2.4% was obtained for five replicated analyses of β-carotene with an enrichment factor of 40. A detection limit of 0.08 μg/mL was achieved. The proposed method was successfully applied to the determination of β-carotene in human serum samples.