| Summary: | 碩士 === 國立臺灣大學 === 環境衛生研究所 === 105 === Perfluoroalkyl substances (PFASs), phthalate esters (PAEs), nonylphenol (NP), and bisphenol A (BPA) are emerging contaminants and ubiquitous in the environment. These compounds are widely used in many consumer and industrial products such as food container, plastics, personal care products and surfactants. They are reported to have adverse effects on reproduction and development and disrupt endocrine system. Moreover, the general population is continuously and simultaneously exposed to them in daily life; food is an important exposure route. Hence, it is crucial to investigate the levels of the above compounds in foods to realize the possible exposure for humans through food intake. However, limited methods are available to determine these contaminants together. Therefore, this study developed and validated a method for analyzing ten PFASs, six PAEs, NP and BPA in six types of foods, including pork, pork liver, pork kidney, fish, clams and oyster. The sample preparation technique QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) was used with acetonitrile as extraction solvent, and Enhanced Matrix Removal (EMR) – Lipid adsorbent was used for sample cleanup. After concentrations, the samples were injected onto ultra-performance liquid chromatography/tandem mass spectrometry (UPLC-MS/MS) with multiple reaction monitoring (MRM) and were quantified with isotope-dilution techniques. Six PAEs were separated on an Ascentis Express F5 column with mobile phases composed of (B) methanol and (A) 5 mM ammonium acetate(aq) (pH = 6.56), and were ionized with positive electrospray ionization (ESI+). The rest analytes were separated with a BEH C18 column with mobile phases composed of (B) methanol and (A) 10-mM N-methylmorpholine(aq) (pH = 9.6), and were ionized with ESI-.
The results of optimization on QuEChERS sample preparation showed that acidification of aqueous phase and use of dispersant methanol during liquid-liquid extraction (LLE) didn’t improve extraction efficiencies of most analytes. Besides, EMR-Lipid was superior to the primary secondary amine (PSA) as cleanup sorbents since less analytes were lost during dispersive solid phase extraction (d-SPE) cleanup step. One-gram sample size and 4 mL of supernatant taken for cleanup after LLE offered lower ion suppression (IS%) compared with two-gram sample sizes and all the acetonitrile extract (about 9 mL). The matrix effect factors of pork, pork liver, pork kidney, fish, clams and oyster were 63.6-168%, 43.0-147%, 63.7-153%, 60.9-198%, 63.5-149% and 50.8-153%. The extraction efficiencies of six foods were as follows: 14.7-96.8%, 50.9-95.7% (except for DEP and BBP extraction efficiency 10.6% and 2.82%), 29.8-93.7% (except for BBP extraction 1.99%), 20.0-104%, 22.3-105%, and 17.6-106%. The limits of detection (LODs) of analytes in six foods were as follows: 0.17-9.70 ng/g wet weight (w.w.), 0.23-17.9 ng/g w.w., 0.16-11.2 ng/g w.w., 0.21-8.35 ng/g w.w., 0.17-9.53 ng/g w.w. and 0.21-8.61 ng/g w.w., respectively. This study tested the method accuracy and precision at five spiked levels in these foods, and most of the quantitative bias were lower than 30%, except DEHP, DINP, DIDP and NP, which were affected by the background levels; most relative standard deviations were below 20%.
This method was applied to investigate analytes in foods collected from three major traditional markets in Hsinchu City. DINP was detected in most food samples with concentrations ranging from 124 to 908 ng/g w.w. BBP were found in pork liver and kidney with levels from 33.1 to 177 ng/g w.w. Most long-chain PFASs were detected in the pork liver with concentrations of sub- to few ng/g w.w.. Perfluoroalkyl carboxylates (PFACs) containing eight or less carbons, BPA and DNOP were not detected in all the food samples. Pork liver was much contaminated with eight analytes (PFNA, PFDA, PFUnDA, PFDoDA, PFHxS, PFOS, BBP and DINP). It is necessary to have additional survey in a large scale to realize the distribution of these contaminants in foods, and to get a better understanding of the possible exposure from food intake.
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