Development of a novel hollow-fiber liquid-phase microextraction based on oil-in-salt and its comparison with conventional one

A novel hollow-fiber liquid-phase microextraction based on oil-in-salt was proposed and introduced for the simultaneous extraction and enrichment of the main active compounds of hesperidin, honokiol, shikonin, magnolol, emodin, and beta,beta'-dimethylacrylshikonin in a formula of Zi-Cao-Cheng-Qi decoction and the single herb, Fructus Aurantii Immaturus, Cortex Magnoliae Officinalis, Radix et Rhizoma, and Lithospermum erythrorhizon, composing the formula prior to their analysis by high-performance liquid chromatography. The results obtained by the proposed procedure were compared with those obtained by conventional hollow-fiber liquid-phase microextraction, and the proposed procedure mechanism was described. In the procedure, a hollow-fiber segment was first immersed in organic solvent to fill the solvent in the fiber lumen and wall pore, and then the fiber was again immersed into sodium chloride solution to cover a thin salt membrane on the fiber wall pore filling organic solvent. Under the optimum conditions, the enrichment factors of the analytes were 0.6-109.4, linearities were 0.002-12 mu g/mL with r(2) >= 0.9950, detection limits were 0.6-12 ng/mL, respectively. The results showed that oil-in-salt hollow-fiber liquid-phase microextraction is a simple and effective sample pretreatment procedure and suitable for the simultaneous extraction and concentration of trace-level active compounds in traditional Chinese medicine.