I am doing the research on characterization of impurities in adapalene by forced degradation (acid, alkali, oxidation etc....), I have getting the separation of the several impurities by HPTLC and now I am doing the characterization of that impurities by LC-MS/MS.
Adapalene have Molecular weight 412.52 gm/mole
I am getting the precursor ion peak at 403.10 m/z, which I cant correlate with its structure. so, please help me this things....
Could you say more about the whole spectrum/ionization mode and other details? Adapalene has formula C28H28O3, so the exact mass is 412.203845. The mass difference between 412 and 403 is 9, which suggests 1/2 H2O, but it would be possible only when two molecules join together with the water loss and the ion should be doubly-charged to obtain m/z 403. [(412x2 - 18)/2=403]. Without seeing the whole spectrum it is difficult to conclude. And what are the fragment ions from the precursor at m/z 403?
I would like to add that more probable is other explanation:
Adapalene molecule losses CH3OH (molecule of methanol) and coordinates Na+ cation, which gives C27H24O2Na+ at m/z 403. Sodium cations are very common in solvents and may also originate from glassware, so sodiated molecules are the most popular in MS spectra (soft ionization techniques).
I am very much agree with Grazyna Bartkowiak answer. I have carried out so many stress degradation studies and sometimes it was observed that the densitograms which we obtain in HPTLC for degraded products are actually the splitting densitograms of the analyte. So if you really want to characterized your degardation product then first you develop a good HPLC method and see the peak purity of your analyte. After that go for stress degradation and separate all the peaks and characterized the products in MS/MS. If you have process related impurities than your results will be more authenticate.
Thanks,
first of all, I am very much thankful to all of you for spending your precious time in my research.
With reference to my problems that, I have provide the data and mass spectra so you could be more helpful in my research.
please find attachment and do the needful.