| Polybrominated diphenyl ethers(PBDEs)are widely used as effective flame retardants.PBDEs and their hydroxyl(OH-PBDEs)and methoxy(MeO-PBDEs)analogues are generally chemically stable,have strong bioaccumulation and Long-distance migration has neurotoxicity and endocrine disruption,so the monitoring and environmental migration behavior of related compounds have received great attention.Although not commercially produced or as a by-product of the process,MeO-PBDEs are currently found in a variety of environmental and biological matrices.The level of environmental pollutants in fish tissues is a recognized sample of environmental pollution levels.At the same time,fish is also one of the most important sources of human exposure to MeO-PBDEs.Therefore,monitoring MeO-PBDEs in fish foods has significant practical significance.Chromatography-mass spectrometry is a common technique for the analysis of such compounds.Compared with liquid chromatography-mass spectrometry,gas chromatography-mass spectrometry has the best sensitivity and separation efficiency,and is the most widely used.At present,gas chromatography-mass spectrometry is the main method for PBDEs and MeO-PBDEs in fish samples.High resolution mass spectrometry is based on gas chromatography-high resolution mass spectrometry because of its strong qualitative ability and low detection limit.There are few studies on MeO-PBDEs in fish tissue.In this paper,the typical MeO-PBDEs with different amounts of bromine-substituted compounds and different methoxy-substituted positions were investigated.The mechanism of mass spectrometry fragmentation on gas chromatography-high resolution mass spectrometry was studied.The determination of fish meat based on gas chromatography-high resolution mass spectrometry was established.High accuracy method for MeO-PBDEs in samples.Specific research content includes:First,a comparison of gas chromatography-time-of-flight mass spectrometry and gas chromatography-double-focus magnetic mass spectrometry(DFS-HR GC/MS)in two high-resolution mass spectrometers,different amounts of bromine-substituted compounds,representative MeOs with different methoxy substitution positions-The fragmentation mechanism of PBDEs compounds.It was found that the difference between the position of the para-para position substitution and the number of bromine substitutions of MeO-has a significant influence on the intensity of the molecular ion peak.The ortho and para-substituted MeO-PBDEs have the highest molecular ion peak intensity.The meta-substituted MeO-PBDEs can be divided into two types,one is the 30 and 3'-substituted MeO-PBDEs.As the number of bromine atoms increases,the intensity of the molecular ion peak continues to rise,and the 5-substituted MeO-PBDEs,the molecular ion peaks are always 100%.The intensity of mass spectrometry fragment peaks of compounds at different ion source voltages in gas chromatography-double-focus magnetic mass spectrometry was studied.The results show that the relative intensity of[M]+ ions of 80%of target compounds is the highest when the ionization energy is 35 ev.Secondly,a high-sensitivity detection method based on the rapid and efficient treatment of QuEChERS pretreatment and 15 kinds of MeO-PBDEs in fish samples was established by DFS-HR GC/MS technology.The performance of the method was systematically evaluated and verified using NIST standards.By optimizing the chromatographic separation conditions,15 kinds of MeO-PBDEs were well separated.The inlet temperature,mass spectrometry ionization energy and other parameters were optimized,and the response of the compounds at different inlet temperatures was evaluated.The linearity,detection sensitivity and repeatability,recovery rate,matrix effect,etc.of the method were evaluated,and the differences between the internal standard method and the external standard method were compared.The results showed that 15 MeO-PBDEs in the range of 1-100 ng g-1 had good linearity,R2 ranged from 0.9824 to 1.0000,and the detection limit was 0.97-2.27 ng g-1.The recovery rate was 62.2%?108.9%.The range and matrix effect ranged from 49.1%to 200.1%.The accuracy of the method was verified by the American National Institute of Standards and Technology's whale standard substance SRM 1945.The recoveries of the two certified MeO-PBDEs ranged from 90%to 112%,indicating that the method can be used.Accurate determination of MeO-PBDEs in actual samples.In this study,high-sensitivity and high-accuracy detection methods were established by gas chromatography-high resolution mass spectrometry combined with isotope dilution mass spectrometry to detect and monitor trace methoxy polybrominated diphenyl ether compounds in complex foods.The risk assessment provides a methodological basis. |
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