基于石墨烯涂层的电喷雾解吸电离质谱技术研究及其在复杂样品分析中的应用

There is a great need for developing new techniques to enable fast, sensitivity, real-time, online, in situ, high throughput and accurate characterization of compounds in complex samples. Mass spectrometry (MS) is a powerful analytical technique that can provide not only high sensitivity, high selectivity and specificity, but also molecular weight and structure information. MS has been considered as an indispensable tool in the trace analysis of chemicals in complex samples. In MS analysis, the matrix of sample has a significant influence on signal intensity of the analytes. Therefore, sample pretreatment (e.g., SPE and SPME) and chromatographic separation (GC, HPLC and CE) usually were required to couple with MS in the analysis of complex samples, such as environmental and biological samples. Tedious sample preparation and chromatographic separation not only consumed a large amount of organic solvent, but also costed a lot time, which has a significant limitation of MS technique on the analysis of large amount and multi-batch samples. In 2004, Cooks's groups developed desorption electrospray ionization mass spectrometry (DESI-MS) technique that allowed the direct analysis of various samples in the open atmosphere with little or no sample preparation, which open new era for the direct analysis of complex samples by MS. Two years later, Chen et al. demonstrated that liquid samples can be analyzed directly in real time using extractive electrospray ionization (EESI), in which ions of analytes are created by charge-transfer collisions between the primary ion cloud generated in an electrospray and a neutral sample plume generated by a separate spray beam. Graphene has attracted considerable interest and become one the most exciting research topics because of its outstanding material, physical, and chemical properties since it was first introduced in 2004. Due to ultrahigh specific surface area, this single-atom thick and two-dimensional nanomaterial has demonstrated great potentials for the use as sorbent materials and assisted matrix in laser desorption/ionization time-of-flight mass spectrometry. This proposal aims method development by using a based graphene coating direct desorption electrospray ionization mass spectrometry for the analysis of complex samples. In this method, graphene will be used both as solid-phase miacroextraction coating for absorption of the analytes and the material for directly desorption electrospray ionization.The proposed method not only could be applied to analysis liquid samples, but also has the potential to analysis gas and solid sample with direct absorped on graphene coating.

发展快速、灵敏、实时、在线、原位与高通量的分析技术是当今分析化学发展的重要趋势。质谱技术是众多分析方法中同时具备高灵敏度和高选择性，且能够在一次分析中同时提供多个被分析物的分子量和结构信息，是分析鉴定复杂样品中未知组分不可或缺的工具。样品纯度是影响质谱信号强度的最重要因素之一，因此传统质谱分析技术往往需要对被分析样品进行净化处理和色谱分离。然而繁琐耗时的样品预处理和色谱分离大大限制了质谱技术在大量、多批次样品分析中的应用。无需样品预处理条件下直接对复杂基体样品中待测物离子化技术的出现，如电喷雾解吸电离和电喷雾萃取电离，使得复杂样品的快速质谱分析成为可能。石墨烯作为一种新型的二维碳纳米材料，近年来迅速成为物理、化学、材料、传感、生物医药等领域的研究热点。本项目拟借助石墨烯大的比表面积和良好的导电导热性能，发展一种基于石墨烯材料的直接电喷雾解吸电离离子化技术，用于复杂样品基体的直接质谱分析。

发展快速、灵敏、实时、在线、原位与高通量的分析技术是当今分析化学发展的重要趋势。石墨烯作为一种新型的二维碳纳米材料，自发现以来迅速成为物理、化学、材料、传感、生物医药等领域的研究热点。由于其大的比表面积（石墨烯2630 m2/g，石墨10 m2/g，碳纳米管1315m2/g）以及独特的材料、物理、化学性质，近年来石墨烯在复杂样品分析领域备受关注。我们制备了多种基于石墨烯的纳米复合材料，然后应用到复杂样品分析方面以提高检测灵敏度。例如制备了石墨烯二氧化硅复合材料（GO@ SiO2）将其作为分散固相萃取的吸附剂用于植物激素分析。测定吲哚-3-乙酸（IAA）、脱落酸（ABA）、吲哚丁酸（IBA）、萘乙酸（NAA）的检测限分别为0.05, 0.04, 0.03 和 0.03 μg/mL。成功应用于多种实际样品的检测，以拟南芥为例，在拟南芥中检测到了IAA、IBA、NAA 等3种植物激素其浓度分别为3.34, 1.62和1.10 mg/kg，RSD小于0.2%。相对于未经GO@ SiO2处理的样品，检测灵敏度提高了10-100倍。氧化石墨烯（GO）作为一种超轻材料，难以从悬浊液中收集。为了解决该问题，我们通过原位化学修饰制备了磁性石墨烯纳米复合材料作为固相萃取吸附剂并用于处理食品中的香料香精类添加剂。5种食品添加剂（乙基香兰素，反式肉桂酸，肉桂酸甲酯，肉桂酸乙酯，肉桂酸苄酯）在10 min内被检测到，检测限为0.02到 0.04 μg/mL。所建立的方法应用实际样品的检测，在果粒橙中检测到乙基香兰素和肉桂酸苄酯，其含量分别为0.33 μg/mL和1.37 μg/mL，巧克力中检测到乙基香兰素对应含量为1.563 μg/g，水果糖中检测到肉桂酸苄酯其含量为0.22 μg/g。我们设计了基于低（聚）核苷酸功能化氧化石墨烯（GO）和脱氧核糖核酸酶I辅助的目标循环放大电化学传感平台用于定量监测环境样品中的汞离子（Hg2+），所建立的方法的测定Hg2+的检测限0.12 nM，线性动态范围上限可以达到50 nM。该方法相对于环境中其它相关的金属离子对汞离子（Hg2+）具有特别高的选择性。该方法还表现出特别高的重现性和良好的准确性，提供了一种扫描监测环境样品中Hg2+的新方法。所建立的基于石墨烯纳米材料的方法被成功应用于多种复杂样品的分析，具有简单、快速、灵敏、高通量等优点。