Enantiomeric separation of R,S-naproxen by conventional and nano-liquid chromatography with methyl-beta-cyclodextrin as a mobile phase additive.
Chiral separations of R,S-naproxen mixtures were obtained on an achiral column (ODS) with methyl-beta-cyclodextrin as a mobile phase additive using conventional and nano-LC. The optimised mobile phase composition was 20 mmol l(-1) methyl-beta-cyclodextrin, 20% (v/v) acetonitrile, and 50 mmol l(-1) sodium acetate buffer at pH 3 using hydrochloric acid for pH adjustment. In addition to UV detection at 232 nm, amperometric detection was also investigated. Without using any internal standard, the reproducibility of amperometric detection (+1.05 V vs. Ag/AgCl) over a long analysis cycle in LC was greatly improved by choosing the peak area ratio between R- and S-naproxen as the analytical readout (the relative standard deviation was 2.11%) and enantiomeric purity could be assessed directly. This method was successfully employed for enantiomeric purity assessment in commercial naproxen tablets. Finally, successful transfer from conventional LC to nano-LC was realised, resulting in over 1000-fold reduction in reagent consumption.
Healy
L O
LO
Department of Chemistry, University College Cork, Ireland.
Murrihy
J P
JP
Tan
A
A
Cocker
D
D
McEnery
M
M
Glennon
J D
JD
D003505:Cyclodextrins / Q000737:chemistry*; D004563:Electrochemistry; D036103:Nanotechnology; D009288:Naproxen / Q000737:chemistry / Q000302:isolation & purification*; D015203:Reproducibility of Results; D013056:Spectrophotometry, Ultraviolet; D013237:Stereoisomerism; D047392:beta-Cyclodextrins
D003505:Cyclodextrins; D047392:beta-Cyclodextrins; C108732:methyl-beta-cyclodextrin; D009288:Naproxen