Research On The Determination Of Phthalate Esters In Food

Phthalate esters are a large group of compounds with softening and shape effect, who were used as plasticizers in the production of packing materials, medical plastic bags, toys, rubber tubes and so on, even used as clouding agents adding into drink and food. The structures of phthalate esters are similar to the biology of endocrine hormone, and they have adverse effects on the endocrine system in humans and environment. Phthalate esters also have the taratogenic, carcinogenic and mutagenic effects. All of these are a serious threat to human health and living standards. Currently, phthalate esters were existed in some complex organisms, such as milk, cooking oil, food packaging materials, and the concentraction of phthalate esters in those samples is very low. Therefore, it is particularly important to establish an accurate, convenient and efficientsample pre-treatment method for determination of phthalate esters in complex samples. In this paper, we have studied three sample pre-treatment technologies, containing ionic liquid hollow fibre-liquid phase microextraction (IL-HF-LPME), dispersive micro-solid phase extraction (D-μ-SPE) based on decanoic acid coated-Fe3O4 nanoparticles, anionic surfactant coacervation phase-dispersive magnetic solid phase extraction (CAP-D-MSPE), combined with high performance liquid chromatography (HPLC) for the pre-treatment and determination of butyl benzyl phthalate (BBP), di-n-butyl phthalate (DBP), dicyclohexyl phthalate (DCHP) and di-n-octyl phthalate(DNOP). The main research contents are as follows:Chapter 1 Determination of phthalate esters in tea beverages by ionic liquid hollow fibre-liquid phase microextraction (IL-HF-LPME) combined with liquid chromatographic detectionThis method breaks the classic single organic solvent was used as the extraction solvent (the acceptor phase) for hollow fibre liquid phase microextraction and the supported liquid membrane phase, ionic liquids l-butyl-3-methy-limidazolium hexafluorophosphate ([BMIm]PF6) was used as the extraction solvent (the acceptor phase) and nonanol was used as the supported liquid membrane phase, vortex assisted liquid liquid microertraction for extraction and preconcentration of three phthalate esters (butyl benzyl phthalate (BBP), di-n-butyl phthalate (DBP), dicyclohexyl phthalate (DCHP)) in tea beverages. Due to the indirectly contact between the extraction solvent and sample solution, good purification function and high enrichment factor were achieved. The optimum conditions of IL-HF-LPME was:8 cm hollow fibre, vortex-mix 4 min, the enrichment factor (EF) was achieved 200. Linear calibration curves obtained by plotting the peak area against the concentration of the respective compounds were found to be linear over the range of 5-1000 ng/mL for all three phthalate esters.The limits of detection (LODs) were 0.67 ng/mL,1.73 ng/mL,1.01 ng/mL for butyl benzyl phthalate, di-n-butyl phthalate, dicyclohexyl phthalate, respectively. Recoveries of the phthalate esters in spikedtea beverages samples were in the range of 94.2 to 103.4%, with the relative standard deviations (RSDs, n=5) were ranged from 0.67 to 1.73%.Chapter 2 Dispersive micro-solid phase extraction (D-μ-SPE) based on decanoic acid coated-Fe3O4 nanoparticles for high performance liquid chromatography analysis of phthalate esters in liquor samplesIn this method, the sysnthesis of Fe3O4@decanoic acid magnetic nanoparticles (MNPs) was a simple coprecipitation reaction, and Fe3O4@decanoic acid magnetic nanoparticles were characterized by using fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Fe3O4@decanoic acid MNPs were used as the adsorbent, and vorex-mix was applied to assist the dispersion, thus a dispersive micro-solid phase extraction for the determination of phthalate esters in liquor sample was established. The optimum conditions of D-μ-SPE were:60μL Fe3O4@decanoic acid MNPs (60 mg/mL, reuse 5 times), vortex for 60 s,1% sodium chloride (m/v). Combined with high performance liquid chromatography-diode array detection, the results showed that linear calibration curves obtained by plotting the peak area against the concentration of the respective compounds, which were found to be linear over the range of 5-1000 ng/mL for all four phthalate esters. All correlation coefficients of the calibration curves were 0.9999, and the relative standard deviations (RSDs, n=5) were in the range of 2.9 to 3.8%.The limits of detection (LODs) were 0.91 ng/mL for BBP,2.17 ng/mL for DBP、2.43 ng/mL for DCI、1.52 ng/mL for DNOP, respectively. Recoveries of the phthalate esters in spiked liquor samples were in the range of 88.9-105.4%. The method was successfully applied for determination and preconcentration of phthalate esters in liquor samples.Chapter 3 Anionic surfactant coacervation phase-dispersive magnetic solid phase extraction (CAP-D-MSPE)-high performance liquid chromatography for the determination ofphthalate esters in tea beveragesIn the CAP-D-MSPE method, anionic surfactant line alkylbenzene suiphonic acid sodium (LAS) was used as extracting agent, which can form micelles in the sample solution and extract phthalate esters, and sodium chloride (NaCl) was added to exhibit phase separation. Fe3O4@diatomaceous earthmagnetic nanoparticles were prepared by using a hydrothermal method, which was used as adsorbent. The method of anionic surfactantcoacervation phase-dispersive magnetic solid phase extraction combined with high performance liquid chromatography was successfully developed to extract and detect of fourphthalate esters in tea beverages. The preconcentration process was achieved in 5 min, the limits of detection (LODs) were ranged from 1.42 to 3.57ng/mL, recoveries were higher than 91.2%, with the relative standard deviations were in the range of 1.82-3.54%.