Problem 11.3

a) What polarity and what kind of analyte ions do you expect to predominate with the following analytes in MALDI? Adjust the second column correctly.

Analyte

Polystyrene

Protein

Oligosaccharide

Fullerene derivative

Polycyclic aromatic hydrocarbon

Oligonucleotide

Peptide

Analyte Ions Formed

[M+H]+, [M+alkali]+

[M+alkali]+

M+.

[M-H], [M-2H+alkali]

[M+H]+, [M+alkali]+

[M+Ag]+

M.

b) The following MALDI spectrum has been obtained from a sample which was assumed to be C120OS, a dimeric fullerene derivative where the bucky balls are linked via O and S.
It has been acquired in the negative-ion mode and nitroanthracene was used as the matrix. The isotopic pattern is not resolved.

Assign composition and charge to the signals.

MALDI spectrum of dimeric fullerene derivative

c) Calculate the theoretical m/z values of the ions in the above spectrum.


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