The differentiation of isomeric biological compounds using collision-induced dissociation of ions generated by fast atom bombardment

Area of Science:

• Analytical Chemistry
• Biochemistry
• Organic Chemistry

Background:

• Fast atom bombardment ionization (FAB-MS) is crucial for analyzing polar and thermally labile biological compounds.
• FAB-MS often yields limited fragment ions, hindering detailed structural elucidation and differentiation of isomers.
• Isomeric compounds frequently exhibit identical mass spectra, posing challenges for identification.

Purpose of the Study:

• To demonstrate the utility of collision-induced dissociation (CID) with FAB-MS for differentiating isomeric substances.
• To apply this combined technique to complex biological molecules like bile acid salts, steroid conjugates, and cyclic nucleotides.
• To assess the sensitivity limits and confirm the identification of biologically relevant compounds.

Main Methods:

• Utilizing fast atom bombardment ionization (FAB) for initial ion generation.
• Applying collision-induced dissociation (CID) to fragment FAB-generated ions.
• Analyzing mass spectra of various isomeric compounds, including bile acid salts, steroid conjugates, and cyclic nucleotides.
• Examining the sensitivity of the CID-FAB-MS technique.

Main Results:

• Collision-induced dissociation effectively differentiates structural isomers that yield similar FAB mass spectra.
• The technique successfully distinguished between various isomeric bile acid salts and steroid conjugates.
• A range of isomeric cyclic nucleotides were also amenable to differentiation using CID-FAB-MS.
• The method demonstrated high sensitivity, enabling the unequivocal identification of two 3',5'-cyclic nucleotides from biological samples.

Conclusions:

• The combination of FAB ionization and CID is a powerful tool for structural analysis of isomeric biological compounds.
• This approach overcomes the limitations of FAB-MS alone, providing detailed structural information.
• CID-FAB-MS enables the precise identification of complex biomolecules, including those found in living systems.