Hi Talha,

From the composition of your compound of interest, you can determine the monoisotopic weight using this tool:

https://www.sisweb.com/mstools/isotope.htm

In the "Calculation Method" specify "High Resolution" if the instrument you are using is resolving the species of interest into its monoisotopes.

Then, using the mass spectrometry vendor's software tools, you can extract the ion or m/z intensity from the total ion current.

As is emphasized by Noel W Davies above, you also need to consider if the m/z is acquired in positive or negative ion mode of the instrument detector so that you can be sure of what you are looking for during the extraction of intensities.

Best,

Hediye.

Hello Talha Baig

it would be desirable if you could show the presumed structure of the target molecule here. The measurements are ESI positive measurements, that take from the spectra, the mass 515 can be the target mass if the molecular weight is 514. With ESI positive mode an M+H adduct is formed, so you get a mass os 515.

Noel W Davies has noted that the isotopic pattern of masses in the 775 and 910 range shows multiple halogen atoms, the pattern at 775 looks like a Cl5 pattern to me, the pattern at 910 looks like a Cl6 pattern. Since the isotope pattern at 515 shows no halogens, the question arises where the halogen compounds come from?

As these are very small signals, they could also be impurities, but the suspected target signal at 515 is not particularly intense either

With a target structure and the reactants that were used, many things could certainly be clarified better, but try the approach of Hediye Erdjument-Bromage and calculate the exact mass of your target molecule and then try to find the signal in your measurements. Don't forget that M+H or M-H adducts are formed, alternatively M+Na (= M+23) for ESI positive.

Good luck and all the best

Joachim Horst