Separation of 13-cis and all-trans retinoic acid and their photodegradation products using capillary zone electrophoresis and micellar electrokinetic chromatography (MEC).
Two retinoic acid isomers; 13-cis retinoic acid and all-trans retinoic acid and their photodegradation products were resolved with capillary electrophoresis (CE) (UV detector, 345 nm) using three different mobile phases: method 1--an acetonitrile modified borate buffer (pH 8.5); method 2--borate buffer (pH 8.5) modified with acetonitrile and alpha-cyclodextrin; and method 3--borate buffer (pH 8.5) modified with SDS (MEC). Concentration of acetonitrile in the buffer was varied from 10 to 50% in method 1 and resolutions of 0-1.9 were obtained for the two retinoic acid isomers. Similarly in method 2, concentration of alpha-cyclodextrin in the buffer (with 10% acetonitrile) was varied from 0 to 40 mM, giving resolutions of 0-3.8. In method 3, concentration of SDS in the buffer was varied from 5 to 60 mM resulting in resolutions of 1.3-4.1. Optimum separation conditions for the three methods were applied to the separation of photodegradation products of the two retinoids after exposure to fluorescent light for 36 h. A buffer modified with 45% acetonitrile and the same buffer modified with 10 mM SDS gave incompletely resolved electropherograms with a 72 cm x 50 microns capillary (50 cm to the detector). A buffer containing 20 mM alpha-cyclodextrin 10% acetonitrile gave completely resolved peaks for each isomer. The buffer containing 10 mM SDS gave completely resolved peaks for the photodegradation products when a 122 cm x 50 microns capillary (100 cm to detector) was used.
Bempong
D K
DK
College of Pharmacy, University of Georgia, Athens 30602.
Honigberg
I L
IL
Meltzer
N M
NM
D002845:Chromatography / Q000379:methods; D004586:Electrophoresis / Q000379:methods; D006863:Hydrogen-Ion Concentration; D015474:Isotretinoin / Q000032:analysis / Q000737:chemistry*; D008027:Light; D013997:Time Factors; D014212:Tretinoin / Q000032:analysis / Q000737:chemistry*
D014212:Tretinoin; D015474:Isotretinoin