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多溴联苯醚(PBDEs)是一种广泛使用的溴代阻燃剂. 据统计,截至2020年,全球PBDEs的总产量已达约200万吨[1].PBDEs的大量生产和使用,使其不可避免地被释放至天然环境中[2-4]. 水体是PBDEs污染的主要环境介质之一,全球多数地区的水体,甚至南北极海洋,均有PBDEs检出[5-6]. 作为全球主要的PBDEs生产国 [1],我国也面临着严峻的水体PBDEs污染形势. 目前,我国华东、华北、华南地区的多数湖泊、河流、海洋均受到了不同程度的PBDEs污染,检出浓度为0.007—43.000 ng·L-1[2]. 水中的PBDEs不但可进入水生生物体内,产生神经发育毒性和内分泌干扰效应,还具备较高的生物放大系数(0.06)和生物蓄积潜力,可通过鱼、贝类等水生食物进入人体,增加神经发育障碍、生殖功能受损和遗传变异的风险[7-9]. 因此,PBDEs的监管对保障水环境安全具有重要意义. 发展水体PBDEs的高灵敏检测方法十分必要.
PBDEs在水体中的赋存浓度通常为痕量或超痕量水平,因此在对其进行检测时需要对样品进行富集等前处理. 固相微萃取(SPME)是一种新型、绿色的样品前处理技术[10]. 与液-液萃取、固相萃取等传统方法相比,SPME技术无需大量有机溶剂,灵敏度更高,且集采样、富集、浓缩、解吸于一体,极大地简化了前处理过程[11],已在多种有机污染物的分析检测中显示了优异的应用性能[12].SPME的技术关键是其涂层. 现有的商用涂层多以石英纤维为基底、机械性能较差,涂层材料热稳定性较低,对PBDEs这类高沸点污染物的分析性能不佳. 因此,亟需开发新型、稳定、可高效富集PBDEs的SPME涂层[13].
共价有机骨架(COF)是一类由C、N、O、H、B等有机元素共价整合而成,具有周期性骨架和有序纳米孔结构的结晶多孔聚合物[14]. 自2005年首次被报道以来,COF已在气体存储、催化、传感、吸附等领域广泛应用[15]. 这类材料比表面积大、孔径范围宽、官能团丰富、热稳定性和化学稳定性好,是理想的SPME涂层材料[12].
本研究采用水热法合成了酮胺型COF材料(TpBD),用硅酮胶黏附法在刻蚀的钢丝表面制得SPME涂层,并对其进行了结构表征. 研究了TpBD涂层对PBDEs的萃取性能,探讨了萃取温度、萃取时间、搅拌速度、解吸温度、解吸时间等条件对萃取过程影响. 优化了萃取条件,建立了基于TpBD涂层的PBDEs分析方法,并在实际水体样品中验证了检测方法的适用性.
基于酮胺型共价有机骨架固相微萃取的水体多溴联苯醚检测
β-Ketoenamine-linked covalent organic framework coated solid-phase microextraction fiber for the determination of polybrominated diphenyl ethers in water
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摘要: 采用水热法合成了酮胺型共价有机骨架材料(TpBD),硅酮胶黏附法制得固相微萃取纤维涂层,探究了该涂层对水中多溴联苯醚(PBDEs)的萃取性能. 利用正交实验优化了TpBD涂层的萃取条件,结合气相色谱技术建立了基于该涂层的水体PBDEs定量分析方法. 研究结果显示,TpBD涂层不但具有良好的热稳定性和化学稳定性,还可高效富集水中的PBDEs,在相同萃取条件下,TpBD涂层对PBDEs的萃取效率是商用涂层的1.2—39.5倍. 基于TpBD涂层的PBDEs检测方法线性范围较宽(2.00—50.00 ng·L−1)、灵敏度高(检出限为0.16—0.45 ng·L−1)、精密度和重现性好(同批次涂层测定结果的日内相对标准偏差(RSD) <14.7%,日间RSD <13.5%;3批次涂层测定结果的RSD <13.1%),在实际环境水样的分析中表现出良好的适用性(加标回收率为81.1%—106.5%).Abstract: In this study, a β-ketoenamine-linked covalent organic framework (TpBD) coating was applied for the solid-phase microextraction (SPME) of polybrominated diphenyl ethers (PBDEs) in water. The TpBD was prepared by the hydrothermal method and was coated on a stainless steel wire by physical adhesion using silicone glue. The PBDE analysis method was established by coupling the TpBD coated fiber with gas chromatography. The extraction conditions were optimized using the orthogonal experiment. The TpBD coating not only had good thermal and chemical stabilities, but also afforded high extraction efficiency for PBDEs (1.2—39.5 times higher than commercial coatings). The method based on TpBD coated fiber for PBDE determination exhibited relatively wide linear ranges (2.00—50.00 ng·L−1), high sensitivity (detection limits of 0.16—0.45 ng·L−1), high precision (intra-day relative standard deviations (RSD) < 14.7% and inter-day RSD < 13.5%), good reproducibility (RSD < 13.1%), and good recoveries (81.1%—106.5%) in real water samples.
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表 1 PBDEs的理化性质
Table 1. Physico-chemical properties of PBDEs.
同类物
Congeners分子式
Molecular formulalg KOW a 蒸气压/(Pa, 25 ℃)
Vapor pressure水溶解度/(mg·L−1, 25 ℃)
Aqueous solubility分子直径/nm b
Molecular diameterBDE-28 C12H7Br3O 5.94 2.19×10−3 0.070 0.989 BDE-47 C12H6Br4O 6.55 2.50×10−4 0.002 0.998 BDE-100 C12H5Br5O 6.86 2.86×10−5 0.040 1.078 BDE-99 C12H5Br5O 7.13 6.82×10−5 0.009 0.995 BDE-153 C12H4Br6O 7.62 5.80×10−6 0.001 1.078 BDE-138 C12H4Br6O 7.91 1.58×10−6 0.001 0.995 注:a正辛醇-水分配系数;b由GaussView 5.0计算.
a n-octanol-water partition coefficient; b calculated by GaussView 5.0.表 2 正交实验的极差分析和方差分析结果
Table 2. Results of range analysis and analysis of variance (ANOVA) for the orthogonal experiments.
条件
Conditions方差分析
Analysis of variance (ANOVA)极距(×105)
Polar distance方差和(×1011)
Sum of variance组间自由度
Degree of freedom
between groups组内自由度
Degree of freedom
within the groupF P 萃取温度/℃ 4.722 5.656 3 44 4.011 0.013* 萃取时间/min 2.479 6.812 3 44 0.842 0.478 搅拌速度/(r·min−1) 8.462 2.541 3 44 26.911 0.000* 解吸温度/℃ 2.110 6.928 3 44 0.582 0.630 解吸时间/min 2.096 6.960 3 44 0.513 0.676 注:* P<0.05. 表 3 基于TpBD涂层的SPME-GC/ECD方法对PBDEs的分析性能
Table 3. Analytical performance of the SPME-GC/ECD method based on TpBD coated fiber
同类物
Congeners线性范围/
(ng·L−1)
Linear range相关系数
Regressioncoefficient检出限
(S/N=3)/
(ng·L−1)
LOD定量限
(S/N=10)/
(ng·L−1)
LOQ日内萃取重复性(n=5)/%
Intra-day
repeatability日间萃取重复性(n=3)/%
Inter-day
repeatability制备重复性(n=3)/%
Fiber-to-fiber
reproducibility富集倍数
Enhancement
factorBDE-28 1.00—50.00 0.999 0.16 0.52 14.7 8.7 8.0 2990 BDE-47 1.00—50.00 0.998 0.20 0.66 14.1 11.3 7.6 2750 BDE-100 1.00—50.00 0.992 0.30 1.00 13.4 12.0 7.2 1970 BDE-99 1.00—50.00 0.996 0.24 0.80 8.2 9.1 9.7 2560 BDE-153 1.00—50.00 0.995 0.40 1.34 10.3 12.9 6.3 2790 BDE-138 2.00—50.00 0.994 0.45 1.50 13.9 13.5 13.1 3820 表 4 基于TpBD涂层的SPME-GC/ECD方法对实际水样中PBDEs的分析结果
Table 4. Analytical results for the determination of PBDEs in real water samples
同类物
Congeners1#水样 2#水样 3#水样 4#水样 5#水样 6#水样 加标回收率(n=3)/%
RecoveriesBDE-28 NDa ND ND ND ND ND 97.6 ± 8.1 BDE-47 ND ND ND ND ND ND 90.8 ± 9.8 BDE-100 0.93 0.32 ND ND ND ND 106.5 ± 11.8 BDE-99 2.45 0.71 0.38 0.25 ND 0.31 96.3 ± 10.6 BDE-153 2.20 0.64 ND ND ND ND 83.7 ± 12.2 BDE-138 4.26 1.05 0.54 ND ND ND 81.1 ± 12.5 注:a 未检出. a not detected. -
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