[Prediction of RP-HPLC retention index for hydroxyl-containing compounds and their glucuronides]

The quantitative relationships between the structure of solutes and their chromatographic retention behaviors have been widely studied. A lot of compounds have been investigated, but drug metabolites have not been involved. Determination of glucuronic acid conjugation is the most important route for investigations of metabolism of drug, while the glucuronide samples are rarely obtained. In this paper the glucuronides have been obtained with the method of biosynthesis in vitro. The peaks of glucuronides were identified by several means including diode-array spectrophotometer detection, beta-D-glucuronidase hydrolysis, glucuronide references and chromatogram comparison of the incubation samples at different times. Two systems have been developed to predict retention index in reversed-phase high performance liquid chromatography based on the molecular structure of the analytes and on the behavior of the parent compounds. We observed a good correlation between retention index of hydroxyl-containing compounds of glucuronides and hydrophobility based on Hansh pi value: I=383.4+136.0pi, n=10, r=0.9912. A good correlation between hydroxyl-containing compounds and their glucuronides was also observed: Y=-471.1+1.4430X, n=11, r=0.9600. The errors in this experiment are less than 12%.