Diffusion of levofloxacin mesylate in agarose hydrogels monitored by a refractive-index method

Coupling mesoporous imprinted polymer based DGT passive samplers and HPLC: A new tool for in-situ selective measurement of low concentration tetrabromobisphenol A in freshwaters

Accurate measurement of tetrabromobisphenol A (TBBPA) is very important because of its widespread environmental pollution. Diffusive gradients in thin films technique (DGT), an in-situ passive sampling method, is regarded as a reliable and robust measurement technique. A new DGT technique based on mesoporous imprinted polymer was combined with high-pressure liquid chromatography (HPLC) method for sampling, preconcentration and monitoring low concentration TBBPA in natural waters. The diffusion coefficient of TBBPA through the diffusive gel was measured by diffusion cell test and simulated using mathematical expression. The effects of different ambient conditions were tested under laboratory conditions and the performance of DGT sampler was validated in natural waters. The diffusion coefficient of TBBPA in the diffusive gel was measured as 2.18 × 10^-6 cm² s^-1 and simulated as in the range 1.41-3.48 × 10^-6 cm² s^-1 by Amsden model. Comparison of experimental and theoretical data, the validity of the experimental method can be verified by the mathematical model. The binding agent with mesoporous imprinted polymer showed selective affinity to TBBPA and its adsorption rate met the requirement of DGT device. The DGT method detection limit was at the level of ng L^-1 for 7 days deployment. DGT sampler was suitable for application in aquatic environment with a range of pH (4.5-7.6), ionic strength (1 × 10^-4 - 0.5 mol L^-1), and dissolved organic matter (DOM) concentration (0-10 mg C L^-1). The coupling method of DGT and HPLC was a promising technique for in situ sampling, preconcentration and monitoring low concentration TBBPA in most typical natural waters.