Rashmi,

1/ If you have XCMS account, you will be able to preprocess your data using jobs (single, pair wise), and putatively identify compounds in samples.

2/ You may also rely on m/z and use of databases such as HMDB, MassBank, KEGG,... to search your compounds of interest.

Noted, compound identification based on single MS is not considered reliable.

Hi Rashmi,

can you still provide some background information on your measurements? (e.g. which substance class ?; was that a synthesis and we now see your reaction mixture ?; is it an extract and if so, from what?). What you can see in the PDF with the designation X1-MS is the following: 1. The mass spectra do not indicate chlorine or bromine. This can be excluded. 2 The molecules are all simply charged [M+H]+. 3. With the help of the nitrogen rule you can say something about the number of nitrogen atoms in the molecules. All even-electron ions (EE+) with an odd number of nitrogens (n=1,3,5...) will appear at even nominal masses (and vice versa). 4. The number of carbon atoms can be estimated by the intensity of the M+1-peak divided by 1.1, because the carbon isotope C13 has a relative frequency of 1.1 %. Did you do the measurements with a TOF? If yes, was the TOF calibrated and did you work with an internal reference mass to compensate for mass shifts during the measurement (e.g. due to expansion of the flying tube)? If yes, then I would only consider sum formula suggestions that are smaller than 5ppm (deviation from the measured mass). Enclosed three links to the topic exact mass and possible sum formulas. If you still have questions, then simply contact me again.

http://www.chemcalc.org/mf_finder/mfFinder_em_new

https://nationalmaglab.org/user-facilities/icr/icr-software

https://www.rsc.org/images/MS1_tcm18-102518.pdf

Regards

Markus

Markus Christ i am working on plant seeds and wanted to identify all antinutritional factors present in it mainly alkaloids, trypsin inhibitors, saponins, tannins n all. this data is from extract (seeds are milled, defatted and extracted in methanol).

Don't know much regarding TOF because i did not performed it personally. But the lab incharge told me to take 10ppm (deviation from the measured mass).

.

Hi Rashmi,

10 ppm deviation is a lot. In the intervall +/- 10 ppm around your measured mass there are many formulas. 10 ppm means that you have 0.001% deviation. E.g. for the mass 392.4399 the interval range is from 392.4360 up to 392.4438. A database search for this range list me 487 suggestions. For structure elucidation you need at least MS/MS. Better is then 1HNMR and or 13CNMR in addition. For this you would have to isolate the individual peaks preparatively for the first time. For NMR it should be at least 2mg per peak. Only with the TOF data alone and the error tolerance of 10ppm a structure elucidation is not possible. You write that these are mainly alkaloids, trypsin inhibitors, saponins, tannins. I would then get some representatives of this substance classes (you can limit it by the measured mass) and analyze them under identical conditions. With the same retention time and the same mass spectrum, you have at least a very strong indication that the peak is the desired compound.

Regards

Markus

Hi Rashmi,

Saponins can probably be ruled out. They often have a C27-C30 skeleton. There we are with a mass of 360. Tannins often have a molar mass of 500-3000 Da. Also this is rather unlikely. Trypsin inhibitors might be a possibility (see https://www.scbt.com/scbt/de/browse/trypsin-Inhibitoren/_/N-148m9o2). The field of alkaloids is quite large. There you have to make restrictions (e.g. because of the mass).

Regards

Markus

Hi Rashmi,

I've found the following link here in the forum:

https://www.researchgate.net/post/How_to_interpret_LC-MS_data_of_a_plant_extract

Regards

Markus