NMR-monitored solid-phase extraction of phenolphthalein glucuronide on phenylboronic acid and C18 bonded phases

Preliminary studies have been undertaken to evaluate the potential of immobilized phenylboronic acid (PBA) for the solid-phase extraction (SPE) of glucuronide metabolites from urine. These studies have demonstrated that immobilized PBA can be used to specifically extract phenolphthalein glucuronide (5 mM) from urine. Urine samples were loaded onto the PBA SPE column in glycine buffer (pH 8.5) and were eluted using methanol-1% HCl (90:10, v/v). The overall recoveries of the phenolphthalein glucuronide for this procedure were high (99%), which compared well with similar studies carried out concomitantly on C18 bonded columns (93%).