New Mexico State University Chlorella Positive Collection - Mass Spectral peak list/Chlorella Positive Class Graph

We illustrate a detailed compositional characterization of hydrothermal liquefaction (HTL) oils derived from two biochemically distinct microalgae, Nannochloropsis gaditana and Chlorella sp. (DOE 1412), for a range of reaction temperature as observed by high-resolution electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS). The unique capability to unequivocally derive molecular formulae directly from FT-ICR MS-measured mass-to- charge ratio (for several thousand compounds in each oil) shows that lipids are completely reacted/converted for any reaction temperature above 200 degrees C and reveals the formation of non-lipid reaction products with increasing temperature. Specifically, lipid-rich oil is obtained at low reaction temperature (less than 225 degrees C) for both microalgal strains. For positive ion mode, the major lipid components in Chlorella sp. and N. gaditana HTL oils are betaine lipids and acylglycerols, respectively. Acidic species in the HTL oils (observed by negative ion mode) are dominated by free fatty acids (FFA) regardless of reaction temperature. HTL oils obtained at higher-temperatures (ge 225 degrees C) are comprised of a variety of basic nitrogen- and oxygen-containing compounds that originate from protein and carbohydrate degradation at elevated temperature. Similar structural features are observed for the abundant nitrogen heterocyclics between the two strains with slightly lower carbon number for Chlorella sp., overall.

本研究对两种生化特性迥异的微藻——加蒂纳米绿藻（Nannochloropsis gaditana）与小球藻属（Chlorella sp.，DOE 1412）——经水热液化（hydrothermal liquefaction, HTL）得到的液化油的组成特性开展了详细表征，实验通过高分辨电喷雾电离傅里叶变换离子回旋共振质谱（high-resolution electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry, ESI FT-ICR MS）分析了一系列反应温度下的产物。该质谱技术可通过FT-ICR MS测得的质荷比，精准推导单一样品中数千种化合物的分子式，结果表明：当反应温度高于200℃时，脂质可完全反应转化，且随温度升高会生成非脂质类反应产物。具体而言，两种微藻在较低反应温度（低于225℃）下均可得到富含脂质的液化油。在正离子模式下，小球藻属与加蒂纳米绿藻HTL液化油中的主要脂质组分分别为甜菜碱脂质与酰基甘油。负离子模式下观测到的液化油酸性组分，无论反应温度如何，均以游离脂肪酸（free fatty acids, FFA）为主。当反应温度≥225℃时，所得HTL液化油主要包含多种含氮、含氧的碱性化合物，这些化合物来源于高温下蛋白质与碳水化合物的降解。两种微藻的液化油中均存在丰富的氮杂环化合物，整体结构特征相似，但小球藻属产物的碳数整体略低。