The tube was folded around a cylindrical magnet (power, 1.4 Tesla; height, 40 mm and O.D, 20 mm) and fixed using glue. The small part of a peristaltic tube around the magnet was packed with Fe 3 O 4 @SiO 2 -diphenyl M. To wet the Fe 3 O 4 @SiO 2 -diphenyl M, 50 mg of the sorbent and 20 mL of water were added into a test tube and sorbent was collected at the bottom of tube with a magnet. The sorbent was withdrawn into a 1 mL polypropylene syringe. The sorbent was transferred into the peristaltic pump tube by very slowly pushing the plunger of syringe. The procedure was repeated to ensure complete transfer of the sorbent. The sorbent was uniformly distributed on the inner wall of the extraction tube. The peristaltic pump and extraction tubes were connected using a piece of a Teflon tube. To perform extraction, a volume of 20 mL of the aqueous sample and 3.6 g of sodium sulfate were added into a 25-mL round bottom flask. After dissolving sodium sulfate, the sample was passed through the extraction tube at flow rate of 0.68 mL min –1 . Analyte desorption was performed by passing 0.5 ml of methanol at the flow rate of 0.05 mL min –1 . The extractant was evaporated to the volume of 250 µL using a mild stream of nitrogen gas. A volume of 20 µL of the extractant was injected into the HPLC system. Under the optimized condition gave low limits of detections (between 0.01 and 0.02 ?g/L), good linearity (from 0.1 to 500 ?g/L, with r 2 between 0.9998 and 0.9999, depending on analytes), and good repeatability of the extractions (relative standarddeviations, below 7%, n=3). The developed procedure was applied to determine phenylurea in environmental water samples.