I have isolated compounds from a plant extract by silica gel chromatography. I would like to further characterize it with LC-MS. What is the minimum amount of sample required for LC-MS. Can anybody help?
Dear Sir,
About 1 mg of the sample required can be in the solid or liquid state. Sample should be pure and free from solvents and metal ions.
Good Luck
Yes for mass spectrometry very small amount of compound is required. If instrument is very sensitive you can use even less than 1mg/ml concentration as well. But for NMR characterisation you need to have atleast 50-70 mg compound
Assuming an analytical column, a few milligrams should be sufficient for LC-MS, maybe less depending on the technique used to purify it before running on LC-MS. Depending on your LC-MS system, you may require a couple of runs- one in positive and one in negative ion mode although some LC-MS systems can switch polarity during the run. Also be aware of adducts that may confuse your measurement. I just did a purification of capsaicin where there peaks were nearly all detected as [M+Na]. Fortunately, I ran a pure compounds and saw the adducts. Other adducts may come from your solvent system (methanol or acetonitrile).
Dear Sir,
About 1 mg of the sample required can be in the solid or liquid state. Sample should be pure and free from solvents and metal ions.
Good Luck
This depends on the limit of detection of your analytical system. This varies from manufacturer to manufacturer and from setup to setup. If you work with a nanoflow system, it can be as low as a few attomoles, but might be a lot more. Ask the person that will make the measurements. They will know what their limit of detection is.
If the compound is easily ionizable, less than 1 mg is required. However, I really recommend prepping up several mg, so you can run NMR on it as well. LC-MS/MS may not be able to distinguish between isomers very easily, and a false identification may occur. UV can also be good to run as well! May I be so bold and give a link to one of my papers on the matter:
http://www.sciencedirect.com/science/article/pii/S0731708510003006
Actually with LCMS you need very few amount of sample. The concentration you will work with is between 1 to 10mg/L and the injected volume is generally 10microL. The real amount needed is ca 1 micro g. Moreover its better to think molar concentration since the Mw range LCMS can treat is very wide. Of course the result depends on the ability of your compound to ionise using API.
Actually, very few amount of purified sample would be enough for LC/MS analysis..depending on the purity of your compounds, I used to take LC/MS analysis of my purified sample in an amount of less than 1 milligram where I prepared a LC/MS sample of approximately 1 mg/mL for the analysis.. the results turned out quite good using such amount of sample for LC/MS analysis..so eventually it is depending your compound's purity and also the LC/MS instrument system as far as I concerned..ionization capabilities of your compounds is also another factor to consider for LC/MS analysis..Good luck and cheers!!
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