Investigation of fragmentation behaviors of steroidal drugs with Li+, Na+, K+ adducts by tandem mass spectrometry aided with computational analysis

Abstract

In this study, we have investigated the fragmentation of the widely used steroidal pharmaceutical drugs (n = 14), complexed by a singly charged proton or alkali metal ion (Li+, Na+, K+) using Ion trap and quadrupole time-of-flight mass spectrometers. Spectra were collected by LC-MS/MS analysis using system automated collision energy i.e., of 25–60 eV. Theoretical calculations were also calculated using DFT software. The metal complexes showed different fragmentation pathways not commonly observed for protonated compounds. There was a distinct difference observed in the relative intensities of some common fragments for free vs. metallated drugs. Some major fragments from protonated and lithium adducts showed close resemblance, while sodium and potassium adducts showed different fragments. Theoretical calculations showed a distinct difference in the position of attachment of proton and metals. This adducts ion fragmentation information will be helpful for the identification of these compounds in complex samples.

Keywords

• Drugs
• Metal adducts
• Fragmentation
• ESI-MS/MS
• Computational studies