【求助】谁能帮我分析结果？－2

应助达人

请问叶片角质单体是什么一类物质？可能是什么什么化合物？（从你掌握的文献或背景知识，让大家对你想要解析的物质有所提示,以便帮助判断）

FID的信号好像和TIC不同步，FID出峰快，是同一根柱子还是两根不同的柱子？

角质层是覆盖在植物地上部分最表层的保护层。角质层由最外层的上表皮蜡质层和角质膜层组成，上表皮蜡质层主要由可溶性的脂肪酸、烷烃、脂肪醇、酮类和酯类组成，作为连续的无定形层位于植物体的最表面。角质膜层主要由羟基脂肪酸聚合形成的不可溶性多聚酯组成。叶片角质单体由角质膜解聚而来，主要有：C16 Acid, C18 Acid,C18:2 Acid,C18:1/3 Acid,C22 Acid,C24 Acid,C16ω-OH Acid, C18:1ω-OH Acid, C16 9/10 Acid,16DiOH Acid, C18 9/10,18 DiOH Acid, and C18 9/10 Epoxy 18-OH Acid，C16 Diacid and C18:1 Diacid.还有一些未知的有机物。不同的植物组成会有很大的变化。

FID 和TIC 不同步是因为信号来自两个不同的柱子。

非常高兴您能打开文件，请判读15min至25min之间的峰。谢谢！

应助达人

粗略看了一下，15-25min中似乎是硅氧烷类的化合物，例如19.58，19.95, 22.36， 22.99， 24.69等，21.23是邻苯二异辛酸酯。好像不是酸。请问您怎样进行样品处理，用过硅胶柱净化吗？

谢谢老师，

样品作了硅烷化反应，但没用过硅胶柱净化。叶片角质的提取及样品处理过程如下：

Delipidation. The leaf samples were extracted by isopropanol at 85 oC for 10 min and room temperature overnight, followed by isopropanol, chloroform/methanol (2:1, v/v), chloroform/methanol (1:2, v/v), and methanol extraction at room temperature 24 h for each. The samples were dried under a gentle stream of nitrogen and afterward were dried in vacuum dessicator for two days.

Depolymerization. Each delipidated sample (10-100 mg) with 25 μg of methyl heptadecanoate (internal standard) reacted with 2 ml of freshly made medium which contained 1.2 ml of methanol, 0.3 ml of methyl acetate and 0.5 ml of 25% sodium methoxide in methanol (Sigma) at 60 oC for 2 h. In each tube, 4ml of dichloromethane, 0.7 ml of glacial acetic acid, and 1 ml of 0.9% NaCl (w/v) Tris 100 mM pH 8.0 were added. The samples were well shaken and phases were separated by centrifugation for 5 min at 3000 rpm. The lower organic phase was collected, washed with 2 ml of 0.9% NaCl (w/v) Tris 100 mM pH 8.0, and dry over anhydrous sodium sulfate, followed by evaporation to dryness under a gentle nitrogen stream.

Derivatization. The dried sample was derivatized with 100 μl of BSTFA and 100 μl of anhydrous pyridine at 80 oC for 1h. The derivatized sample was dried under light stream of nitrogen and resolved in 200 μl of chloroform for GC-MS/FID analysis.

应助达人

明白了，怪不得那么多SiO基团呢。样品用BSTFA衍生化处理，那就是硅烷化产物，解析恐怕更难了。

请老师一定帮忙。
我当重谢。

最好用硅胶柱净化一下

谢谢老师！