Comprehensive analysis of alkenones and alkenoates by reversed phase HPLC-MS with unprecedented sensitivity and selectivity

通过反相 HPLC-MS 全面分析烯酮和烯酸酯，具有前所未有的灵敏度和选择性

• 批准号: 2234875
• 负责人: Yongsong Huang
• 金额: $ 30.44万
• 依托单位: Brown University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-01-15 至 2024-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2234875&HistoricalAwards=false
• 关键词: Comprehensive; analysis; alkenones; alkenoates; reversed

This project will develop sensitive and time-saving analytical methods to quantify an important class of organic compounds, long chain alkenones, in ocean and lake environments. Alkenones are produced only by microalgae belonging to the order Isochrysidales, with no other organisms known to make such compounds. Such unique compounds are termed biomarkers. Alkenone biomarkers are extremely resistant to break-down and have been found in geological sediments as old as 120 million years. Remarkably, alkenones measured from ocean and lake environments display consistent structural changes at different growth temperatures and also track aquatic photosynthetic productivity. Thus, measurement of alkenones in ancient sediments provides quantitative insights to past climate and aquatic productivity. That information helps predict future changes in climate and aquatic ecosystems in the era of global warming induced by human activities. The project Broader Impacts include support for a Ph.D. graduate student, undergraduate student researchers, and a high school summer intern. Traditionally, alkenones are analyzed using gas chromatograph coupled to a flame ionization detector (GCFID), or in extremely low concentration samples, gas chromatograph-chemical ionization mass spectrometry (GCCIMS). However, GCFID is non-selective (i.e., cannot exclude interferences if present) and has relatively low sensitivity and requires tedious sample cleanup for complex samples, whereas GCCIMS displays non-linear and often variable responses to alkenones, which increases analytical uncertainties. The proposed research takes advantage of the latest advances in high pressure liquid chromatograph mass spectrometry (HPLCMS). Preliminary data shows that the new reversed phase HPLC-MS based analytical methods will have much higher sensitivity (up to two orders of magnitudes), and exceptional selectivity (i.e., strong capability to exclude interferences) for analyzing alkenones. The proposed work includes testing various liquid chromatographic conditions (solvent elution schemes, column types) to optimize the chromatographic separation of long chain alkenones. Mass spectrometry parameters including two different ionization modes (atmospheric pressure chemical ionization, or electrospray ionization), and various electronic settings will also be optimized. A series of algal culture samples will be grown at different temperatures and measured using the traditional GCFID method. These culture samples will then be used as standards for calibration between the authentic alkenone proxy values and HPLCMS based measurements. A large set of global ocean surface sediments collected from diverse ocean environments and containing variable interferences will be analyzed to fully validate the new reversed phase HPLCMS methods.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

该项目将开发灵敏且省时的分析方法，以量化海洋和湖泊环境中一类重要的有机化合物，即长链烯酮。烯酮仅由属于等鞭藻目的微藻产生，目前还没有其他已知的生物体能够产生此类化合物。这种独特的化合物被称为生物标志物。烯酮生物标记物具有极强的抗分解能力，已在距今 1.2 亿年的地质沉积物中发现。值得注意的是，从海洋和湖泊环境中测量的烯酮在不同的生长温度下表现出一致的结构变化，并且还跟踪水生光合生产力。因此，对古代沉积物中烯酮的测量为过去的气候和水产生产力提供了定量的见解。这些信息有助于预测人类活动引起的全球变暖时代气候和水生生态系统的未来变化。该项目更广泛的影响包括对博士学位的支持。研究生、本科生研究人员和高中暑期实习生。 传统上，使用气相色谱仪与氢火焰离子化检测器 (GCFID) 分析烯酮，或者使用气相色谱-化学电离质谱 (GCCIMS) 分析极低浓度的样品。然而，GCFID 是非选择性的（即，不能排除存在的干扰），并且灵敏度相对较低，并且需要对复杂样品进行繁琐的样品清理，而 GCCIMS 对烯酮显示非线性且经常变化的响应，这增加了分析的不确定性。拟议的研究利用了高压液相色谱质谱（HPLCMS）的最新进展。初步数据表明，基于反相 HPLC-MS 的新型分析方法对于分析烯酮将具有更高的灵敏度（高达两个数量级）和出色的选择性（即排除干扰的能力强）。拟议的工作包括测试各种液相色谱条件（溶剂洗脱方案、色谱柱类型）以优化长链烯酮的色谱分离。质谱参数包括两种不同的电离模式（大气压化学电离或电喷雾电离）以及各种电子设置也将得到优化。一系列藻类培养样品将在不同温度下生长，并使用传统的 GCFID 方法进行测量。然后，这些培养物样品将用作真实烯酮代理值和基于 HPLCMS 的测量值之间校准的标准品。将对从不同海洋环境中收集并含有可变干扰的大量全球海洋表面沉积物进行分析，以充分验证新的反相 HPLCMS 方法。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值进行评估，被认为值得支持以及更广泛的影响审查标准。