✍ Scribed by Erwin J. Alvarez; Jennifer S. Brodbelt
No coin nor oath required. For personal study only.
The analysis of a targeted group of nucleoside antibiotics has been accomplished through the use of selective ion-molecule reactions and collision-activated dissociation (CAD) techniques in a quadrupole ion trap. A series of homologous ether reagent ions generated from dimethyl ether, di-n-butyl ether and 2-methoxyethanol were used as chemical ionization reagents. Because chemical ionization with dimethyl ether and di-n-butyl ether reagent ions did not provide selectivity and signal enhancement for the analysis of these biopharmaceuticals, a chemical ionization reagent with special hydrogen-bonding capabilities was used. The reagent ion that showed the greatest promise is a product of 2-methoxyethanol, CH,OCH,CH,OCH, +. This highly reactive species, which reacts selectively with nitrogen-containing compounds, can undergo both nucleophilic attack and anchoring via hydrogen bond formation between the methoxy oxygen and an acidic hydrogen of the nucleoside substrate. The reaction of the CH30CH,CH20CH,+ ion with each of the nucleoside antibiotics resulted in formation of ( M + 131' and [ M + 891 + products. The CAD spectra indicated that the adducts are covalently bound species and that the nucleotide moiety dominates both the reactive and dissociative behavior of the nucleoside antibiotics.
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