This protein has a molecular weight of roughly 12,000. The singly charge ion shows up at 12(thousand), the doubly charged is 6 and the triple charge is 4. Plus, because this is MALDI, we have a whole lot of matrix in there, which also shows up in the lower part of the spectrum.

@@shortchemistry7927 thank you for the response! What Matrix were you using in this graph? Also, do you know around what m/z a DHB matrix with a 5-mer would show up around?

yes, you can do serum analysis with MALDI-TOF, but depends on the target compound(s) of your interest, optimization of matrix choices, sample preparation and instrument conditions are needed. co-crystallization of analytes with MALDI matrix is not necessary. the original MALDI experiment that was done the NOBEL winner used metal powder with glycerol. and ionic matrix sample preparation also doesn't form crystal most of time. currently, the best MALDI-TOF instrument is from Bruker, Rapiflex or timsTOF can serve for most of applications.