26


September 2009


Reversed Phase ChiralMethod Development Using Polysaccharide-based Stationary Phases


by Liming Peng1 , Tivadar Farkas1 , Swapana Jayapaian1 , and Chankvetadze, Bezhan2


1. Phenomenex, Inc., 411Madrid Ave., Torrance, CA 90501 USA (www.phenomenex.com) 2. Institute of Physical and Analytical Chemistry, Tbilisi State University, Tbilisi, Georgia


Developing simple and straightforward reversed phase chiral HPLC separations coupled with highly sensitive MS detection is highly needed for conducting drug metabolism and pharmacokinetic studies of stereoisomers in the drug development process. Polysaccharide- based chiral stationary phases (CSPs) are most prevalent in chiral LC due to their wide applicability and good selectivity. However, most chiral separations on polysaccharide CSPs are carried out under normal phase (NP) conditions with mobile phases (e.g. hexane/IPA) which may be incompatible with MS detection due to their high flammability in ion sources operated at high temperature. While separations conducted in polar organic (PO) mode utilize mobile phases that potentially prevent analyte ionization in the source, rendering them undetectable. The most promising separation mode for chiral LC/MS analysis is reversed phase (RP) LC. Moreover this separation mode is also complementary in selectivity to NP and PO separation modes (with either MS or UV detection).


We present results based on a study involving over 200 racemates of pharmaceutical interest on the CSPs cellulose tris(3,5-dimethylphenylcarbamate), cellulose tris(3-chloro-4-methylphenylcarbamate) and amylose tris(5-chloro-2- methylphenylcarbamate) in reversed phase mode with UV or MS detection.


Experimental Conditions: Instrumentation: HPLC System: Agilent 1100 series (www.agilent.com)


Pump: G1311A Quaternary Pump Autosampler: G1313A ALS UV Detection: G1315A Diode Array Detector


MS Detection:TurbolonSpray® - ESI, Positive Ion Mode; MRM; heater gas flow 5000 cc/min; heater temperature 400 °C


Figure 1: Representative Enantioseparations in RP DimetindeneMaleate


Flavanone


Tetramisole Ambucetamid


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