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ANANBIOANAL - 2010
Pharmaceutical R & D Summit
doi:10.4172/2155-9872.1000072
Comparison Of Different Mass Spectrometry Ionization
Techniques to Analyze Desogestrel in Plasma Samples
Martin Maurer1
, Luigi Silvestro1
1
2
, Adelina Moise2
, Isabela Tarcomnicu2
, Simona Rizea Savu1
3S-Pharmacological Consultation & Research GmbH, Koenigsbergerstrasse, Germany
Pharma Serv International SRL, Bucharest, Romania
Introduction: The development of HPLC-MS/MS has opened completely new
horizons in analytical chemistry: polar and unstable compounds can be now easily
analyzed with adequate sensitivity. Apolar compounds, once considered as best
target for mass spectrometry, are now a critical class of compounds for HPLC-MS.
In the present work desogestrel, a progestogen often used in therapy, has been
selected as a model apolar compound to compare GC/MS and HPLC-MS/MS, with
and without derivatization, in order to develop a highly sensitive quantitative method.
Materials and methods: In case of HPLC-MS/MS electrospray, atmospheric pressure
chemical ionization, photoionization and experimental electron capture sources
were tested. In case of GC/MS both electron impact as well as chemical ionization
(positive and negative) were employed. The samples were analyzed as such or after
derivatization with trimethylsilylimidazole (GC only), heptafluorobutyrylimidazole or
pentafluoropropionylimidazole. The same SLE method was used for desogestrel
isolation from plasma samples (0.6 ml aliquots) both for GC-MS and HPLC-MS/MS
analyses.
Results and conclusions: In HPLC-MS/MS the best results (LLOQ 200 pg/ml
desogestrel in plasma), without derivatization, were obtained with the photoionization
source using a reversed phase separation. The derivatization with perfluorinated
imidazoles gave adequate derivatives for electron capture ionization; critical technical
aspects are still under evaluation due to the experimental source employed. With
GC-MS a better sensitivity was achieved in case of the derivatives (LLOQ 50 pg/
ml), using negative chemical ionization; a long analytical separation, with a 60 m
DB-5 column, was however mandatory in order to eliminate the interference from
endogenous compounds.
ANALBIOANAL-2010
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