Fragmentation studies on monensin A by sequential electrospray mass spectrometry

Area of Science:

• Analytical Chemistry
• Mass Spectrometry
• Organic Chemistry

Background:

• Monensin A is a polyether ionophore antibiotic with significant applications.
• Accurate characterization of Monensin A using mass spectrometry is essential for quality control and research.
• Electrospray Ionization Sequential Mass Spectrometry (ESI-MSn) is a powerful technique for analyzing complex molecules.

Purpose of the Study:

• To investigate the structural identity and fragmentation pathways of the m/z 671 ion in Monensin A analysis.
• To differentiate between the protonated parent ion and other ion structures at m/z 671.
• To elucidate the fragmentation mechanisms governing Monensin A under ESI-MSn conditions.

Main Methods:

• Electrospray Ionization Sequential Mass Spectrometry (ESI-MSn) was employed.
• Analyses were conducted using quadrupole time-of-flight (Q-tof) and Fourier-transform ion cyclotron resonance (FT-ICR) mass spectrometers.
• Accurate-mass measurements were utilized to confirm all fragment ions.

Main Results:

• The ion at m/z 671 was identified as consisting of two different ions with the same accurate mass, dependent on sample preparation.
• One ion was the monensin protonated parent ion, while the other was derived from the loss of water from the monensin water adduct.
• Distinct fragmentation patterns were observed for each of the two m/z 671 ions, with Grob-Wharton type fragmentations noted for the protonated parent ion.

Conclusions:

• The study successfully differentiated two distinct ion structures at m/z 671 in Monensin A ESI-MSn analysis.
• Understanding these distinct fragmentation pathways is critical for accurate interpretation of Monensin A mass spectrometry data.
• The proposed fragmentation pathways provide valuable insights into the behavior of Monensin A under mass spectrometry conditions.