Research On Sample Pre-treatment Technology And HPLC Analysis Of PAHs

Polycyclic aromatic hydrocarbons (PAHs) are persistent pollutants that spread widely in the environment. Most of the problems linked with the analysis of PAHs in water are associated with their low concentration levels. A suitable pre-treatment method is therefore needed to enhance the detection limits and it can affect the lifetime of the detection instrument as well. Traditional analytical methods such as soxhlet extraction, liquid-liquid extraction or solid-phase extraction need many time-wasting operations, some of them also consume plenty of toxic organic solvent that are hazards to both the environment and the human beings. In order to develop rapid and efficient pre-treatment processes to determine PAHs in environmental samples, we have carried out the following innovative works:(1) Carbon coated Fe3O4magnetic particles (Fe3O4/C) are synthesized by hydrothermal reaction, and characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), vibrating sample magnetometer (VSM) and transmission electron microscopy (TEM). The material is applied in microwave-assisted extraction for clean-up and enrichment of polycyclic aromatic hydrocarbons (PAHs) from tree leaves. Magnetic solid-phase extraction (MSPE) parameters including elution solvents, amount of sorbents and enrichment time are optimized together with microwave extraction time, power, extraction solvents and the ratio of liquid to solid. Under the optimal conditions, the developed method provides spiked recoveries of77.7-103.8%with RSDs of less than4.0%, and limits of detection (LOD) of0.5-2.0ng g-1. PAHs in tree leaves are successfully determined.(2) Multilayer of octane-1,8-dithiol&Au NPs modified ordered TiO2nanotube array was synthesized by anode oxidation, pulse electroplating and self assembly methods. The obtained material was applied to pre-concentration PAHs in environmental water samples. The overall appearance and outer surface of the magnetic particles was studied by SEM and FTIR spectroscopy was employed to examine the surface groups. Solid-phase extraction (SPE) parameters including elution solvents, enrichment time, desorption time and pH of the solvent are optimized. Under the optimal conditions, the developed method provides spiked recoveries of74.04%-112.52%with RSDs of less than10.52%, and limits of detection (LOD) of0.25-2.0ng L-1. It is a suitable method to determine PAHs in water samples.(3) Surfactant enhanced ultrasound assisted extraction combined with high performance liquid chromatography was used to establish a method for determine PAHs in water samples. Parameters that may affect the extraction process including the amount of surfactant, the amount of organic solvent and extract solvent are optimized. Under the optimal conditions, the method was applied to real water sample. It provides spiked recoveries of84.62%-101.02%with RSDs of less than8.14%and limits of detection (LOD) of0.25-2.0ng L-1. It is a simple and fast method to determine PAHs in water.