Kashiyama Yuichiro, Kitazato Hiroshi, Ohkouchi Naohiko
Department of Earth and Planetary Science, University of Tokyo, Tokyo 113-0033, Japan.
J Chromatogr A. 2007 Jan 5;1138(1-2):73-83. doi: 10.1016/j.chroma.2006.10.028. Epub 2006 Oct 27.
We describe an improved method for purification of sedimentary vanadyl and nickel porphyrins (i.e., naturally occurring metalloalkylporphyrins). For the purpose of compound-specific isotopic analyses, various sedimentary porphyrins were purified from the complex natural mixtures by the dual-step high-performance liquid chromatography (HPLC) method. The high-sample-capacity reversed-phase HPLCs by adding N,N-dimethylformamide to the mobile phase allow an efficient collection of fractions containing the target compounds even using analytical-scale columns. Furthermore, this method achieved improved chromatographic resolutions but significantly reduced the overall retention time down to 60% compared with the previous work. The target compounds were then isolated with the normal-phase HPLC with the baseline-resolution, which is necessary to avoid chromatographic isotopic fractionation. One of the advantages of this method is that it requires neither derivatization nor demetallation. The purity of these isolated compounds was demonstrated by various HPLC online detection methods utilizing a photodiode-array detector, a mass selective detector. The overall recoveries of Ni porphyrin, VO porphyrin, and porphyrin-free base, respectively, were estimated to be approximately 50-60%, 65%, and 85%.
我们描述了一种用于纯化沉积钒卟啉和镍卟啉（即天然存在的金属烷基卟啉）的改进方法。为了进行化合物特异性同位素分析，通过两步高效液相色谱（HPLC）法从复杂的天然混合物中纯化了各种沉积卟啉。通过向流动相中添加N，N - 二甲基甲酰胺的高样品容量反相HPLC，即使使用分析规模的色谱柱也能有效地收集含有目标化合物的馏分。此外，与之前的工作相比，该方法提高了色谱分辨率，但将总保留时间显著缩短至60％。然后用具有基线分辨率的正相HPLC分离目标化合物，这对于避免色谱同位素分馏是必要的。该方法的优点之一是既不需要衍生化也不需要脱金属。利用光电二极管阵列检测器、质量选择检测器的各种HPLC在线检测方法证明了这些分离化合物的纯度。Ni卟啉、VO卟啉和无卟啉碱的总回收率分别估计约为50 - 60％、65％和85％。
