GC-MS for Analyte Identification in Isotope Ratio Mass Spectrometry (Combined GC-MS/IRMS)

用于同位素比质谱分析中分析物鉴定的 GC-MS（GC-MS/IRMS 组合）

• 批准号: 514589248
• 金额: --
• 依托单位: Technische Universität München (TUM)
• 依托单位国家: 德国
• 项目类别: Major Research Instrumentation
• 财政年份: 2022
• 资助国家: 德国
• 起止时间: 2021-12-31 至 无数据
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/514589248?language=en
• 关键词: GC; MS; Analyte; Identification; Isotope

Over recent years we have been advancing compound-specific isotope analysis (CSIA) to trace sources of organic groundwater contaminants, and to decipher their natural transformation from compound-specific isotope values. Gas chromatographic (GC) separation of target compounds is followed by online conversion to CO2 for direct isotope analysis of 13C/12C by isotope ratio mass spectrometry (IRMS). While IRMS is uniquely suited to determine accurate isotope ratios, structural information is lost during combustion to CO2. Hence, the identity of analytes cannot be confirmed independently. Early applications of CSIA were little affected, because they targeted contaminated sites, where analytes were present in high concentrations (mg/L) compared to background organic matter. Hence, pollutants stood out as characteristic peaks in GC-IRMS chromatograms and could be reliably identified by their retention times. We have been striving to expand the CSIA approach also to so-called micropollutants: pesticides, pharmaceuticals and consumer care products which occur in much smaller concentrations (low micrograms/L to nag/L range). In GC-IRMS chromatograms their peaks are, therefore, typically embedded in a contiuum of co-eluting peaks from organic matter leading to prominent research challenges. (i) Analysis of field samples warrants unique compound identification, yet frequently shows subtle changes in chromatographic retention times making them unreliable for analyte identification. (ii) At the same time, our current research efforts would greatly profit from structural elucidation of these interferences to optimize approaches for their targeted removal. This application, therefore, requests funding for crucial instrumentation to be combined with existing IRMS instrumentation: a GC with a conventional quadrupole mass spectrometer (qMS) and an interface for compound conversion prior to IRMS analysis. This equipment will allow splitting the GC flow so that one part goes through the interface into the IRMS for isotope analysis, while the other part is directed to the qMS to enable simultaneous structural identification. Not only will this setup support our measurements at natural abundance that depend on identification of target analytes and background interferences. It will also benefit a second research avenue that we pursue with funding by the International Atomic Energy Agency (IAEA): the identification of micropollutant metabolites by application of a stable isotope-labelled pulse where radioactive labelling is impossible. We will lead a Coordinated Research Network to trace the fate of 13C labelled antibiotics, metabolites and antibiotic resistance in an agricultural field experiment. Here, GC-IRMS instrumentation will be able to detect chromatographic peaks of 13C-labelled metabolites as “needles in the haystack”, while GC-MS analysis would enable simultaneous structural elucidation of these unknown metabolites.

近年来，我们一直在推进化合物特异性同位素分析（CSIA），以追踪有机地下水污染物的来源，并从化合物特异性同位素值中破译其自然转化。目标化合物的气相色谱（GC）分离之后，在线转化为CO2，用于通过同位素比质谱法（IRMS）进行13 C/12 C的直接同位素分析。虽然IRMS是唯一适合于确定准确的同位素比，结构信息在燃烧过程中损失的二氧化碳。因此，无法独立确认分析物的同一性。CSIA的早期应用几乎没有受到影响，因为它们针对的是污染场地，与背景有机物相比，这些场地的分析物浓度较高（mg/L）。因此，污染物在GC-IRMS色谱图中突出为特征峰，并且可以通过其保留时间可靠地鉴定。我们一直在努力将CSIA方法扩展到所谓的微污染物：农药，药品和消费者护理产品，这些产品的浓度要小得多（低微克/升到纳克/升范围）。因此，在GC-IRMS色谱图中，它们的峰通常嵌入在来自有机物质的共洗脱峰的连续体中，导致突出的研究挑战。(i)现场样品的分析保证了独特的化合物鉴定，但经常显示色谱保留时间的细微变化，使其不可靠的分析物鉴定。(ii)同时，我们目前的研究工作将大大受益于这些干扰的结构阐明，以优化其靶向去除的方法。因此，本申请要求为与现有IRMS仪器相结合的关键仪器提供资金：带有传统四极杆质谱仪（qMS）的GC和IRMS分析前的化合物转换接口。该设备将允许分离GC流，使得一部分通过接口进入IRMS进行同位素分析，而另一部分被引导至qMS以实现同步结构鉴定。这种设置不仅支持我们在天然丰度下的测量，这取决于目标分析物和背景干扰的识别。这也将有利于我们在国际原子能机构（原子能机构）资助下开展的第二个研究途径：在不可能进行放射性标记的地方，通过应用稳定的同位素标记脉冲来识别微污染物代谢物。我们将领导一个协调研究网络，在农业田间实验中追踪13 C标记的抗生素，代谢物和抗生素耐药性的命运。在这里，GC-IRMS仪器将能够检测13 C标记的代谢物的色谱峰，就像“大海捞针”一样，而GC-MS分析将能够同时对这些未知代谢物进行结构解析。