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Complex sample pretreatment and Chromatographic analysis

 Microextraction technology and high-performance liquid chromatography analysis of additives in complex samples

        A simple method based on hollow fiber liquid-phase microextraction (HF-LPME) followed by high performance liquid chromatography (HPLC) analysis was successfully developed for the determination of UV filters in cosmetic products. A canular extractor was assembled by mounting a hollow fiber inside an external tube with a tee-connector. The organic solvent was immobilized into the fiber to form a liquid membrane as the acceptor phase. The sample was continuously injected into the extractor and the UV filters were extracted from the aqueous sample into organic acceptor phase. Toluene has been verified to be suitable as the acceptor phase. Under the optimized HF-LPME conditions, the enrichment factors of five UV filters varying from 24 to 57 were achieved. The limits of detection for the five UV filters were in the range of 1-100g L-1. The relative standard deviations (RSDs) of HF-LPME and HPLC analysis were lower than 5.2%. Good correlation coefficients (R2) with excellent linearity for target analytes were higher than 0.9960. The proposed method has been successfully applied to the analysis of the varied cosmetic products.

        Preparation Fe3O4/CNTs solid phase micro-extraction materials, coupled with high-performance liquid chromatography detected vanillin and ethyl vanillin of the milk. Hydrothermal preparation Fe3O4, 3-aminopropyl triethoxysilane was used to aminate surface, of magnetic nanomaterials, connecting with carboxylated carbon nanotubes to prepare solid phase micro-extraction Fe3O4/CNTs material. Fe3O4/CNTs as solid phase micro extraction materials investigated solvent elution, adsorption capacity, extraction time, pH and ionic strength of samples. Using methanol as elution solvent, under optimized conditions, the recoveries of vanillin and ethyl vanillin in milk were greater than 92.1%. Detection limit of Vanillin and ethyl vanillin were10 μg L-1, the linear correlation coefficients were greater than 0.9940. The proposed method had been successfully applied to detect vanillin and ethyl vanillin in the milk quickly and efficiently.