Hopmans Ellen C, Kienhuis Michiel V M, Rattray Jayne E, Jaeschke Andrea, Schouten Stefan, Damsté Jaap S Sinninghe
Royal Netherlands Institute for Sea Research, P.O. Box 59, 1790 AB Den Burg, Texel, The Netherlands.
Rapid Commun Mass Spectrom. 2006;20(14):2099-103. doi: 10.1002/rcm.2572.
Ladderane lipids, containing three or five linearly concatenated cyclobutane moieties, are considered to be unique biomarkers for the process of anaerobic ammonium oxidation, an important link in the oceanic nitrogen cycle. Due to the thermal lability of the strained cyclobutane moieties, the ladderane lipids are difficult to analyze by gas chromatography. A method combining high-performance liquid chromatography coupled to positive ion atmospheric pressure chemical ionization tandem mass spectrometry (HPLC/APCI-MS/MS) was developed for the analysis of the most abundant ladderane lipids, occurring as fatty acids and ether-bound to glycerol. Detection was achieved by selective reaction monitoring of four specific fragmentations per ladderane lipid. Detection limits of 30-35 pg injected on-column and a linear response (r(2) > 0.99) over nearly 3 orders of magnitude were achieved for all compounds. Using this method, these unique ladderane lipids were for the first time identified in a surface sediment from the Gullmarsfjorden, in concentrations ranging from 1.1-5.5 ng/g for the ladderane fatty acids and of 0.7 ng/g for the monoether. It is foreseen that this method will allow the investigation of the occurrence of anaerobic ammonium oxidation in natural settings in much greater detail than before.
梯烷脂质含有三个或五个线性连接的环丁烷部分，被认为是海洋氮循环中一个重要环节——厌氧氨氧化过程的独特生物标志物。由于环丁烷部分的热不稳定性，梯烷脂质难以通过气相色谱进行分析。本文开发了一种结合高效液相色谱与正离子大气压化学电离串联质谱（HPLC/APCI-MS/MS）的方法，用于分析以脂肪酸形式存在并与甘油醚键结合的最丰富的梯烷脂质。通过对每种梯烷脂质的四种特定裂解进行选择性反应监测来实现检测。所有化合物的柱上进样检测限为30 - 35 pg，在近3个数量级范围内具有线性响应（r(2) > 0.99）。使用该方法，首次在古尔马湾的表层沉积物中鉴定出这些独特的梯烷脂质，梯烷脂肪酸的浓度范围为1.1 - 5.5 ng/g，单醚的浓度为0.7 ng/g。可以预见，该方法将比以往更详细地研究自然环境中厌氧氨氧化的发生情况。
