Published:Journal of Chromatographic Science,
ISSN 0021-9665 Volume
46, Number 1, January 2008, pp. 35-41
Analysis of Dihydropyridine Calcium Channel Blockers
Using Negative Ion Photoionization Mass Spectrometry
Alberto S. Pereira, Beatriz Bicalho, Jaime
O. Ilha, and Gilberto De Nucci
Galeno Research Unit, Campinas, SP, Brazil
The fragmentation of dihydropyridine calcium-channel
antagonists are compared by electrospray ionization (ESI) and
atmospheric pressure photonization (APPI). The results demonstrate
that in ESI the preferred ionization process is in positive mode,
with the mass spectra of [M+H]+ showing base peak ions probably
formed by loss of alcohols from carboxyl groups. Conversely,
in APPI, a high intense peak is observed in negative mode due
to deprotonated molecule [M–H]– after two serial
1, 2-hydride shifts leading to a rearranged deprotonated molecule
[M–H]–. These ions undergo another 1,2-hydride shifts
to produce a nitro-phenyl product ion of m/z 122. The APPI is
also used to develop a method for the quantitation of dihydropyridines
(e.g., nifedipine) in human plasma.
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