Differentiation of Two Geometric Isomers of the Pharmaceutical Eprosartan Using Atmospheric Pressure Chemical Ionization

✍ Scribed by Jeffrey Brum; Robert Hannah

• Book ID: 101238505
• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 71 KB
• Volume: 11
• Category: Article
• ISSN: 0951-4198
• DOI: 10.1002/(sici)1097-0231(19970830)11:13<1430::aid-rcm7>3.0.co;2-5

✦ Synopsis

The utility of an atmospheric pressure chemical ionization interface for distinguishing stereoisomers has been demonstrated. Two geometrical isomers of the pharmaceutical eprosartan ((E,Z)-3-[butyl-1-(4-carboxybenzyl)-1H-imidazole-5-yl]-2-[2-thienyl)methyl]propenoic acid) were investigated in the positiveand negative-ion modes with in-source collision-induced dissociation (CID). In positive-ion mode, CID spectra display significant differences between the two isomers. Under identical collisional conditions several fragment ions present in the CID spectrum of the E isomer (SK&F 108566) are significantly suppressed in the spectrum of the Z isomer (SB 206328). Analysis of the fragmentation patterns of both isomers indicates that a pathway initiated by the loss of neutral thiophene from the E isomer is inhibited in the CID spectra of the Z isomer. In negative-ion mode, fragmentation and corresponding differences in spectra are not observed. Fragmentation is observed to result primarily from the ionization process.