Mixed hemimicelles SPE based on CTAB-coated Fe3O4/SiO2 NPs for the determination of herbal bioactive constituents from biological samples

In this paper, a solid-phase extraction (SPE) method based on mixed hemimicelles of cetyltrimethyl ammonium bromide ((TAB) on silica-coated magnetic nanoparticles (MNPs) is developed for extraction and preconcentration of compounds from the biological samples. We selected item and emodin which are the major active anthraquinones of rhubarb as model analytes. A high performance liquid chromatography-fluorescence detection (HPLC/FLD) method was developed for the determination of item and emodin in urine and serum samples. The main factors influencing the extraction efficiency including the amount of surfactant, the concentration of MNPs, the shaking time and the desorption ability of organic solvents were investigated and optimized. No interferences were caused by proteins or endogenous compounds in urine and serum samples. Good linearities (r(2) > 0.9995) for all calibration curves were obtained, and the limits of detection (LODs) for them and emodin were 0.2 and 0.5 ng/mL in urine samples and 7 and 10 ng/mL in serum samples, respectively. Satisfactory recoveries (92.76-109 90% and 97.53-107 72% for rhein and emodin) in the biological matrices were achieved. (C) 2009 Published by Elsevier B.V.