Dear Ekta,

Looking at the MALDI-MS spectrum there are several peaks, meaning you have a mixture of compounds in your ethanol precipitate. This doesn't mean they are all polysaccharides - please note that other molecules also precipitate with ethanol.

Also, the predominant peaks in your MALDI-MS spectrum are even-numbered - this means these ions contain an odd number of nitrogen atoms (n=1, 3, 5,...) known as the nitrogen rule. Based on published literature or previous experiments, is this something expected?

But before moving on, you'll need to confirm if the ions observed in the MALDI-MS are singly-charged, or doubly- or triply-charged... Just check the mass difference between adjacent peaks (deltam/z =1 means singly charged, delta m/z =0.5 means doubly charged, and so on....). Once you figure that out for all major ions in your MALDI-MS spectrum then you can start searching the literature and hypothesizing what molecules you have in your MALDI-MS spectrum. To confirm your hypothesis, you'll need to conduct MALDI-MS/MS experiments.

Hope this helps,

Ana

Ana Reis Thank you so much, ma'am.