I'm currently working with an aquatic plant. I want to extract and isolate polyhydroxy alkaloids from it. My problem is that I'm afraid that I have done a big mistake. I dried the plant and crushed it into powder. Then I extracted it by soaked in 100% methanol and 50% aqueous methanol for 4 times. From TLC result, there is separation with 100% methanol but not very good. The TLC solvent system is ethanol:water:acetic acid (9.5:0.5:0.1) and I used C-18 silica plate. Then I analyzed with GC-MS using MSTFA in pyridine by this condition : column BP5MS, initial program 50 degC (hold 1 min), increase to 300 degC at rate 5 degC/min and held 5 min at 300 degC. The result showed alkaloid (but the highest was d-tert-leucine) and none of polyhydroxy alkaloids. My question is :
1. Is it ok if I dried my plant materials? Did it affect the polyhydroxy alkaloid compounds? Unluckily, I didn't have any fresh material left. T_T...
2. Did my extraction method ok? Does there any solvent system for TLC besides I used in order to get better separation thus further use for column chromatography?
3. Does anyone have best/optimum operating condition for GC-MS analysis using MSTFA in pyridine for polyhydroxy alkaloids in details?
Attached below the picture of separation using solvent system that I used. Thank you for your time and kindness by helping me. =)
This link might help you, it is an overview for these sort of compounds: https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0CB4QFjAA&url=http%3A%2F%2Fwww.researchgate.net%2Fpublication%2F11169378_Polyhydroxy_alkaloids_chromatographic_analysis%2Flinks%2F0912f5112b0efa31ae000000.pdf&ei=drulVIaxEcukNvbpgfAC&usg=AFQjCNGwdKfi-eQZ26V7j-8ivRdkFl4juQ&bvm=bv.82001339,d.eXY
I don't believe your extraction procedure was bad. You _probably_ did no harm drying your plant material, and if you couldn't process it right away, drying was probably best to avoid mold.
Generally polyhydroxy alkoloids are light sensitive this clearly observed from the changed of color after evaporation of the solvent. Try to check FT-IR of your extract after evaporation of the solvent to see if you have poly hydroxy alkaloid present or not?
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