In this work, novel water-dispersible size controlled nanocomposite based on zirconium alkoxide as metal organic precursor was fabricated and subsequently applied for rapid, efficient and selective preconcentration of gallic acid in human plasma and herbal tea samples. The resultant nanocomposite (Fe3O4@Zr(OtBu)4@Laurate) was characterized by Fourier transform infrared, scanning electron microscope and X-ray spectrometer, while laurate forms aggregates on the surface of the nanocomposite and thereby improves sorption of gallic acid. The effects of some variables on efficiency of gallic acid from real samples were optimized by central composite design; while optimum points were achieved as follows: pH 3.5, 35.0 mg of nanocomposite, 150.0 L of eluent and 3.0 min sonication time. Chromatographic separation was carried out on analytical Nucleosil C18 column (250 × 4.6 mm I.D., 5 m particle size) at ambient temperature with methanol: water (40:60, v/v) pH adjusted at 3.5 follow by UV detection at 270 nm. Acceptable limit of detection (0.2 g kg-1) and wide linear range (1.0-700.0 μg kg-1) in coincidence with reasonable enrichment factor (EF=125) are the unique advantages, which promise this method for quantification of this compound in real samples with complicated matrices.
