Possible molecules can be identified in library in GCMS instrument. 

Can you give us some more details?  First of all, do you have any experience with mass spec data or are you new to this?  If you're new, how did you carry out your part of the experiment, and who carried out the actual mass spectrometry?  It's difficult to answer your question as it stands.  For example, what do you mean by 'results'? Do you have exact masses for the major peaks in your chromatograms?  Presumably you have spectra for the GC-MS experiments, but do  you have CID spectra from the LC-MS experiments or only the m/z values for the protonated (or deprotonated) molecules?  Exact masses or nominal masses?  Mass spec data is very difficult to interpret on your own!

Thank you Sir (Dr. John S Wishnok)  for your interest in my question. Sir, I have the library list for GC- MS along with predicted Formula, Molecular weight and compound structure. For LC-MS I have two graphs, one with        x-axis: minutes and y-axis: MCount , and another with x-axis: Retention time and y-axis: Retention time shift (min). LC-MS result also came with a Mass library hit list. It contains list of compound and structures. The library used for GC-MS are Wiley8.lib and Nist08s.lib. I outsourced the work from an outside lab. Currently I don't have the facilities at my University. My other confusions regarding the compounds identified are:

1) Till what mass or molecular weight can the GC-MS detect.

2) Till what mass or molecular weight can the LC-MS detect.

3) Is it possible to identify a compound in both GC-MS and LC-MS.

4) What is the accuracy of the predicted compound through library scan?

Sincerely

Kavisa Ghosh

Dear Kavisa

The GC MS can detect up to 1000 M.W. but normaly it is used for only up to 400-500 D.a.

In LC MS there is very differen tkind of model according to your requirement but normaly mass  in LC Ms can be detected up to 10-20 thousand.

Yes it is possible if the compound nature is suitable for both GC as well as LC then it is possible to analyze by both the techniques.

The accuracy depends of your Substraction of background If Background substraction is proper and there is no contamination then library matched probability is more then 85-90%

Here we are doing so many compounds which is suitable for GC as well as LC MS.

Thank you Dr. Chandresh Soni for clarifying my doubts. I have one more doubt regarding isolation of the fraction containing the compound of interest. If a library hit provides us a result in LC-MS, for example, that at 450 nm absorption, the compound X is present. If this Compound X is having the pharmacological properties of my interest, what would be the next step? Can we start with the collection of the  fraction and then analyse it with HPLC, NMR (H1, C13, etc,.) and then analyse the structure? Sir, a reference paper for the complete understanding of this procedure would be very helpful. Sir, I also would like to know if your center provides training in this field of study. 

Sincerely

Kavisa Ghosh

Dear Kavisa

There are many points you should keep in mind before you start you LC-MS experiment. You should refer to the literature of the plant you want to work on and collect the MS and LC data of the compounds reported in the plant. Once you have all the MS details you can compare the experimental MS data you have with this  data to get an preliminary for the presence of the compounds reported in literature. If you are searching for a particular compound then you may go for the comparison of the fragmentation pattern with the LC-MS library and then target its isolation 

Thank you Sir (Dr. Atish Paul) for your reply. I will follow your suggestions. 

Sincerely

Kavisa Ghosh

Dear Kavisa, 

I think the previous comments provided most of the guidance and info you are looking for. Just to add (and maybe repeat some of the points), yes it's possible to have compounds that can be analysed (and detected) in both systems GC/LC-MS. This always depends on the chemical nature of the compound.

If you are looking for specific compounds (with pharmacological properties), firstly you need to search in the literature those compounds (if they have been studied before, and if they have been analysed before on either GC-MS or LC-MS, the physical and chemical properties/characteristics, etc.) all this can help you decide on: (i) the extraction method to follow, (ii) analytical platform to use, etc. This targeted approach would easy your analysis, as it will guide your steps to get to the answer. 

As you mentioned you've already received some results. Still check the literature for the specific compounds you are looking for and check the points I mentioned above for those compounds. Compare with the protocol you followed. If closely related, then you can check the (m/z, Rt) features that correlate to what the literature reports. That might then be putatively your compounds of interests. Then you would need to perform more experiments for confirmation.

Hope this helps.

Regards,

Fidele 

Dear Kavisha, The suggestion given by Dr. Paul is absolutely correct way to explore any medicinal plant.

Dear Kavisa,

All contributions were good. But i go with Fidele Tugizimana's suggestions. And in ation 

Dear Kavisa,

the most impotant is already said. The extraction protocol you used may help you providing a first approach on the compound, i.e. more or less lipophilic. Compounds that are detected with both platforms, GC-MS and LC-MS, have low vapour pressure, and probably, high lipophilic character. Also you might bear in mind what ionization source was used (ESI, APCI, EI, DART, ...) to consider the possible ions/adducts you are obtaining ([M+H]+, [M+NH4]+, [M+ACN+H]+, [M-H]-, [M+HCl-H]-, [M+CH3COOH-H]-, [M+2H]+2, [M+3H]+3, and so on) in order to look for the proper m/z in the databases. I do not understand well what you mean with "450 nm" in a LC-MS analysis.

Hope this also help you. Regards,

Olimpio

Kavisa, Even I 'm finding the same problem...

Is your interpretation is over ...Will you suggest me?

Possible molecules can be identified in library in GCMS instrument. 

Dear Kavisa,

the full answer to your ambigous question is not easy and cannot be short. First of all, you should tell us which aspect/feature of your data is raising the concern: feature (m/z-retention time) adscription to particular compounds, results' comparison between extracts, extract effects on a particular system (cells, antioxidant test, ...), how to discern which the differential compounds between extracts are effective, etc.

Regards,

Olimpio

if you come to know plz share with me

Sorry, but I am in the same mess as you. just got results of some oil samples I sent for GCMS analysis. Don't know a hoot on how to interpret these results.

Sorry , am facing the same chalenges with gcms and nmr result

i was going to ask this same question. I have some fish samples i recently analysed using gc-ms but i am having difficulties with the interpretation of the result.

hello, if you are working with essential oils you should take a look at this book:

Adams, R. P. (1989). Identification of essential oils by ion trap mass spectroscopy.

we use it in our laboratory to validate Essential oil's GC-MS database results.

good luck

i am asking the same question for LCMS plz if anyone know tell me as well.

The answer is very simple, go get help from the GC/LCMS expert on your lab or go to the person who gave you the results. Follow a GCMS identification course, spent some weeks (or better months) learning GC/LCMS. Analyse test samples and play with the results, let a collegae make some mixtures or extracts for you to analyse and interpret. And only after you have learned how to interpret GC/LCMS data start working on real samples. If you don't want to spent time learning GC/LCMS leave the interpretation to some one who knows.

So many people who are not guided by an expert asking how to interpret GC/LCMS data. It's like bringing your car to a car repair shop and the car "mechanic" asking on the internet how to repair your car…… It is worrying that I see so many of these questions on research gate.

Regards, Alex

Through library match with nist

Read this book it will give you lot of information..

Qudsia Tabassam , Thanks a lot

Hi Hecham Im looking for this book that you have mentioned " Adams, R. P. (1989). Identification of essential oils by ion trap mass spectroscopy " can you please help me to find it maybe online. appreciate your help. Noor @hicham Mechqoq

hello i have done too LCMS of a plant extract, but unable to interpret the data. could anyone please suggest a way or a book which could help me out.

thanks

Conference Paper Interpretation of GC MS Results

Hello,

If you want interpret the GC/MS or LC/MS data yourself the, acquire instrument specific RAW data (eg. MzXML or other). If RAW data is not in particular format convert that using another tool like ProteoWizard. Now, use that RAW file for your metabolite interpretation and statistical analysis as well.

XCMS, MassChoroViever, Mass Bank, Maven these are simple software by which you can analyze you data. XCMS is the online tool.

Hi Dr. Kavisa Ghosh ,

possible compound can be found by GC/MS analysis following the library of GC/MS and in that repost you have got, but for LC/MS you have to see the molecular weight of the compound and compare with the same one in GC/MS following by M/Z ratio. yes most of the same compound you can see both in GC/MS and LC/MS analysis.