| 题名 | 复杂基质中金属及其化合物纳米材料的 形态分析方法研究 |
| 作者 | 周小霞 |
| 学位类别 | 博士 |
| 答辩日期 | 2016-05 |
| 授予单位 | 中国科学院研究生院 |
| 授予地点 | 北京 |
| 导师 | 刘景富 |
| 关键词 | 纳米颗粒，形态分析，金属纳米颗粒，金属离子，元素质量粒径分布 Nanoparticles, Speciation analysis, Metal nanoparticles, Metal ions, Elemental mass size distribution |
| 其他题名 | Speciation Analysis of Metal and Metal Compound Nanoparticles in Complex Matrices |
| 学位专业 | 分析化学 |
| 中文摘要 | 金属及其化合物纳米材料具有优异的理化性质，因此得到了大量的生产和广泛的使用，应用领域涉及工业生产、医疗器械和日常用品等。这些产品在生产、使用和处理过程中会不可避免地会释放到环境中，给环境生物和人体健康造成潜在的威胁，已引起了公众的广泛关注。纳米材料比表面积大，自身性质活泼，具有高度动态性，一旦进入环境或生物体中，会发生一系列的物理化学转化，最终以不同形态的颗粒存在于环境和生物体中，尤其是一些金属和金属氧化物纳米材料。他们在进入环境和生物体后，会释放金属离子，而这些金属离子又会与 S2-、Cl-等阴离子反应生成金属化合物纳米颗粒。研究报道，不同形态的金属颗粒，其毒性和生物效应相差很大。因此，发展金属及其化合物纳米材料的形态分析方法，研究金属及其化合物纳米材料在环境和生物体中的迁移转化，有助于更加科学地评价其潜在的环境风险。 本文针对几种典型的金属及其化合物纳米材料的形态分析开展了相关的研究工作。基于液相色谱（LC）和电感耦合等离子体质谱（ICP-MS）联用技术及多种表征技术相结合，发展了水环境、抗菌产品和生物体中不同粒径、不同化学组成金属及其化合物纳米颗粒和金属离子的分离富集、测定及表征方法，并研究了其在环境和生物体中的物理化学转化。同时，基于磁固相萃取与分步洗脱结合，发展了水环境中具有不同化学组成的含银纳米颗粒、银离子的分离测定以及它们去除回收方法。论文主要包括以下内容： 第一部分，概括地介绍了纳米材料的种类、来源及其释放途径；重点分析了纳米材料在环境和生物体中的转化行为及影响其毒性的相关因素；综述了近年来关于纳米材料分离、检测及表征的相关方法。 第二部分，基于 LC与 ICP-MS联用方法，建立了抗菌产品中含银纳米颗粒和银离子的快速分离分析方法。使用孔径 500 ?的氨基键合的改性硅胶为固定相的色谱柱，以 Na2S2O3和 FL-70的混合溶液作为流动相，流速 0.7 mL/min，5 min内实现了 1-100 nm范围内全部含银纳米颗粒与银离子的快速液相色谱分离。研究表明，流动相中 FL-70和 Na2S2O3的加入有效地保证了含银纳米颗粒和银离子的洗脱，同时 500 ?孔径是实现银离子和小粒径含银纳米颗粒（~ 1 nm）基线分离的关键因素。样品消解后直接 ICP-MS测定总银含量，银离子经 LC分离后进ICP-MS定量，纳米银浓度由总银含量扣除银离子含量获得。该方法对于银离子和纳米银的检出限为 0.019 μg/L，适用于抗菌产品和环境水样中含银纳米颗粒的形态分析，具有操作步骤简单、耗时短、适用粒径范围宽和分析结果重现性好等 金属及其化合物纳米材料具有优异的理化性质，因此得到了大量的生产和广泛的使用，应用领域涉及工业生产、医疗器械和日常用品等。这些产品在生产、使用和处理过程中会不可避免地会释放到环境中，给环境生物和人体健康造成潜在的威胁，已引起了公众的广泛关注。纳米材料比表面积大，自身性质活泼，具有高度动态性，一旦进入环境或生物体中，会发生一系列的物理化学转化，最终以不同形态的颗粒存在于环境和生物体中，尤其是一些金属和金属氧化物纳米材料。他们在进入环境和生物体后，会释放金属离子，而这些金属离子又会与 S2-、Cl-等阴离子反应生成金属化合物纳米颗粒。研究报道，不同形态的金属颗粒，其毒性和生物效应相差很大。因此，发展金属及其化合物纳米材料的形态分析方法，研究金属及其化合物纳米材料在环境和生物体中的迁移转化，有助于更加科学地评价其潜在的环境风险。 复杂基质中金属及其化合物纳米材料的形态分析方法研究优点，为纳米银的环境行为和毒理效应的研究提供了有效的定量和表征技术手段。 在上述研究基础上，进一步建立了 LC-ICP-MS测定环境水样中纳米金属氧化物及其相应的金属离子含量的方法。使用孔径 1000 ?改性硅胶为固定相的色谱柱，以含 10 mM十二烷基硫酸钠（SDS）的醋酸缓冲液（pH 7.0, 10 mM）为流动相，流速 0.5 mL/min，在 10 min内实现了金属离子与纳米金属氧化物的基线分离。研究发现，当纳米金属氧化物的粒径大于尺寸排阻限时，纳米金属氧化物被部分保留或全部截留在 LC柱中，使得其经过 LC柱后回收率降低。因此，在本研究中，金属离子含量直接通过 LC-ICP-MS测得，而纳米金属氧化物浓度则由样品中该金属总含量扣除金属离子含量获得，金属的总量由 ICP-MS测定消解后的样品获得。为防止大粒径纳米金属氧化物堵塞柱子，可定期用含 EDTA的流动相冲洗柱子。相比超滤、过滤和浊点萃取等已有方法，本方法可有效分离小粒径纳米金属氧化物和金属离子，并 抑制金属氧化物溶解释放金属离子，适用于环境水样中纳米金属氧化物和金属离子的分析。 论文第四部分发展了复杂基质中纳米颗粒的元素质量粒径分布（EMSD）测定方法。基于尺寸排阻（SEC）和 ICP-MS在线联用，分离了不同粒径的纳米颗粒。分离过程中，由于粒径与保留时间呈现非常好的线性关系，可通过保留时间计算成粒径，通过仪器校正，得到纳米颗粒的粒径分布。同时，由于不同粒径的纳米颗粒 ICP-MS响应与粒径无关，因此可对不同粒径纳米颗粒进行定量，得到其元素质量粒径分布。该参数集元素组成、颗粒粒径分布和元素质量为一体，可用于复杂基质中痕量纳米颗粒的指纹识别和定量，区分具有微小差异的纳米颗粒，识别痕量的 Ag2S NPs和核壳结构的 Au@Ag NPs，定量追踪纳米颗粒在复杂基质中的迁移转化行为，为分析和追溯复杂基质中的纳米颗粒提供了有效的技术手段。 论文的最后一部分主要围绕环境水样中不同化学组成的含银纳米颗粒的形态分析和和回收而展开研究。研究发现，水热法合成的磁性四氧化三铁纳米颗粒经老化后，可选择性吸附纳米银、纳米氯化银和纳米硫化银等含银纳米颗粒，而不吸附银离子。腐殖酸的存在会降低含银纳米颗粒萃取效率，但加入 Ca2+可有效消除腐殖酸的影响。为进一步区分萃取吸附到磁性纳米颗粒表面的不同化学组成的含银纳米颗粒，采用了分步洗脱法分别对其进行定量测定：先用 2% HAc（v/v）选择性洗脱纳米银和纳米氯化银，再用含 10 mM硫脲的 2% HAc（v/v）混合溶液洗脱纳米硫化银，并用 ICP-MS分别测定不同形态含银纳米颗粒含量。该方法中，老化的磁性四氧化三铁颗粒对不同形态纳米银最大吸附量为 19.9-62.8 mg/g，可用于不同形态含银纳米颗粒和银离子（加 Cl-转化为 AgCl NPs）的去除和回收。本方法可定量测定以下形态的 Ag：银离子（Ag+）、纳米银（Ag0）和纳米氯化银（AgCl）的总量、纳米硫化银（Ag2S），为不同含银纳米颗粒的定量测定提供一种可靠手段，对科学评估纳米银的环境风险及其生物效应具有重要意义。同时，也为去除和回收环境中不同形态含银纳米颗粒和银离子提供了有效方法。 |
| 英文摘要 | Because of their unique chemical and physical properties, metal and metal compound nanoparticles are widely applied in consumer and industrial products. The increasing production and widespread usage of nanoparticles resulted in their increasing release into the environment during the production, application, recycling and disposal, and therefore enhanced their exposure and risk to ecosystem and human health. Because of their high surface areas, nanoparticles are highly dynamic in the aqueous and biotic system, and once entered into the environmental and living system, they are inclined to occur chemical and morphology transformation. Especially for some metal and metal oxide nanoparticles, they are subject to release metal ions which can react with some anions like S2- in the environment to form nanoparticles of metal compounds. Both physical and chemical transformation would in turn alter their bioavailability and toxicity. Therefore, to exactly assess the environmental risks and further understand the toxicity mechanism of metal and metal compound nanoparticles to organism, accurate speciation analysis of nanoparticles in the complex matrices is of great importance. This dissertation focuses on speciation analysis of some typical metal and metal compound nanoparticles in complex matrices, such as environmental waters and biological matrices. Coupling liquid chromatography (LC) with inductively coupled plasma mass spectrometry (ICP-MS) and other characterization techniques, we have developed methods for separation,preconcentration,characterization and quantification of trace nanoparticles in environmental waters, antibacterial products and biological matrices, as well as quantitatively studied the transformation of nanoparticles in acquatic environments and biological matrices. In addition, based on magnetic solid extraction and sequential elution, a method for speciation analysis and recovery of typical silver-containing nanoparticles (AgCNPs) in waters was developed. In the first part, we summarized the category, source and release pathways of nanoparticles. In addition, the behaviors of nanoparticles in the environmental and living system, as well as the major factors influcing toxicity of nanoparticles were discussed. Then, we presented the update methods used for extraction, separation, analysis and characterization of nanoparticles. In the second part, a method for speciation analysis of AgCNPs and silver ions in environmental waters and antibacterial products was developed based on coupling LC with ICP-MS. By using a 500 Å poresize amino column, and an aqueous mobile phase containing 0.1% (v/v) FL-70 (a surfactant) and 2 mM Na2S2O3 at a flow rate of 0.7 mL/min, all the nanoparticles of various species such as Ag and Ag2S were eluted in one fraction, while dissoluble Ag(I) was eluted as a baseline separated peak. The dissoluble Ag(I) was quantified by the on-line coupled ICP-MS. It was demonstrated that the addition of FL-70 and Na2S2O3 into the mobile phase is essential to elute AgCNPs and Ag(I) from the column, and the use of 500 Å poresize column is the key to baseline separation of Ag(I) from ~1 nm AgNPs. AgCNPs was quantified by subtracting the dissoluble Ag(I) from the total Ag content, which was determined by ICP-MS after digestion of the sample without LC separation. The limits of determination of AgCNPs and Ag+ were 0.019 µg/L. The proposed method is a robust method for speciation analysis of AgCNPs and silver ions in antibacterial products and environmental waters, providing an efficient approach for analysis and characterization of AgCNPs in environmental waters and antibacterial products. We further developed a method for speciation analysis of total metal, metal oxide nanoparticles (MO NPs) and metal ions (Mn+) in the environmental waters. By using a 1000 Å poresize silica column, and an acetate buffer (pH 7.0, 10 mM) containing 10 mM sodium dodecyl sulfate (SDS) as mobile phase at a flow rate of 0.5 mL/min, Mn+ and MO NPs with sizes smaller than the column poresize were baseline separated within 10 min, whereas MO NPs with sizes larger than the exclusion limit were filtered off by the column. The high recoveries (> 97%) of Mn+ from the LC column ensured their accurate quantification directly with the online coupled LC-ICP-MS,while the quantification of MO NPs by subtracting the Mn+ content from the total metal content, which was determined with ICP-MS after digestion without LC separation. In oder to avoid the clog of column, a mobile phase containing EDTA was adopted to dissolve and flush the large MO NPs out of the column. Although two run of ICP-MS determination had to be conducted to respectively quantify the total metal content and Mn+, compared to the existing methods, such as ultrafiltration, filtration and CPE, our method provides a robust approach for (i) discrimination of metal ions from MO NPs with small sizes (e.g. <5 nm); (ii) prohibition the dissolution of MO NPs to release metal ions; (iii) robust analysis of real samples with complex matrices.Therefore, it provides a powerful tool for studying the fate and toxicity of MO NPs in environmental waters. In the fourth part, we developed a one-step method for rapid measurement of elemental mass size distribution (EMSD) by online coupling of size exclusion chromatography (SEC) with ICP-MS. Different sized nanoparticles were separated and the retention time was linearly correlated with particle diameter. The established d-tr equation allow the generation of size distribution profiles of NPs by correcting the instrumental broaden based on the monodisperse Ag+ peak after converting the tr of the SEC chromatogram to d. The ICP-MS sensitivity of all the NPs agreed well to that of their ionic counterparts, allowing the quantification of elemental mass distributed in different sized NPs. Then, we demonstrated that EMSD, integrating elemental composition, particle size distribution and mass, is a simple parameter that can be used for the direct fingerprinting and quantification of trace level NPs in complex matrices. More importantly, EMSD offers a straightforward fingerprint for discriminating NPs with minimal differences, identifying trace Ag2S NPs and core-shell nanocomposite Au@Ag, and quantitatively tracking the transformation of NPs, providing an efficient method for analysis of NPs in complex matrices. In the last part, a novel method for speciation analysis and recovery of different AgCNPs was developed. Aged iron oxide magnetic particles (IOMPs) were found to be both excellent adsorbents in selective extraction and sacrificial oxidants in elution of AgCNPs including silver nanoparticles (AgNPs), AgCl NPs and Ag2S NPs in the presence of Ag+. Maximum AgCNP extraction was obtained at pH 5-7, and Ca2+ was efficient in eliminating the interference of humic acid on the AgCNP extraction. By sequential elution of AgNPs and AgCl NPs with 2% (v/v) acetic acid and Ag2S NPs with 10 mM thiourea in 2% (v/v) acetic acid, a new method was developed for their speciation analysis. Exhibiting maximum adsorption capabilities in the range of 19.9-62.8 mg/g for the studied AgCNPs, the aged IOMPs were applied to recover AgCNPs and Ag+ (pre-transformed to AgCl NPs by adding Cl-) in water samples with satisfactory removal efficiencies and recoveries. Therefore, our work not only offers a novel approach for speciation analysis of AgNPs and Ag2S NPs, but also provides an efficient procedure for removal and recovery of AgCNPs and Ag+. |
| 内容类型 | 学位论文 |
| 源URL | [http://ir.rcees.ac.cn/handle/311016/37061]  |
| 专题 | 生态环境研究中心_环境化学与生态毒理学国家重点实验室 |
| 推荐引用方式 GB/T 7714 | 周小霞. 复杂基质中金属及其化合物纳米材料的 形态分析方法研究[D]. 北京. 中国科学院研究生院. 2016. |
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