SINGLE-RUN ANALYSIS OF ISOMERS OF RETINOYL-BETA-D-GLUCURONIDE AND RETINOIC ACID BY REVERSED-PHASE HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY

Reversed-phase HPLC methods capable of separating several retinoic aci d isomers are generally not designed for simultaneous analysis of isom ers of other classes of retinoids. A reversed-phase HPLC method is pre sented which allows the separation of at least four retinoic acid (RA) isomers (13-cis-RA, 9,13-dicis-RA, 9-cis-RA, all-trans-RA) and of all isomers of retinoyl-beta-D-glucuronide (RAG), which have been observe d in vivo (13-cis-RAG, 9-cis-RAG, all-trans-RAG). The recovery of reti noids was generally between 80 and 90%. Intra-day reproducibility (exp ressed as relative standard deviation) was less than or equal to 7.0%. As little as 0.25 ng of RA isomers and of all-trans-RAG could be dete cted. This method allowed the study of the metabolism of 9-cis-retinoi ds, where isomerization reactions play a predominant role.