High-performance liquid chromatography with electrochemical detection for the determination of 7-monohydroxyethylrutoside in plasma.

MonoHER (7-monohydroxyethyl rutoside) is a semisynthetic flavonoid, which can be used as a modulator for doxorubicin-induced cardiotoxicity. To study the pharmacokinetics of monoHER in mice and human an HPLC procedure was developed to measure the level of monoHER in plasma. After extraction of monoHER with methanol, the supernatant was equally diluted (v/v) with 25 mM phosphate buffer (pH 3.33). This solution was analysed by HPLC, using a reversed-phase ODS column, with a mobile phase consisting of 49% methanol and 51% of an aqueous solution containing 10 mM sodium dihydrogen phosphate (pH 3.4), 10 mM acetic acid and 36 microM EDTA. The retention time of monoHER was about 5.2 min. The lower limit of quantification of monoHER was set at 0.3 microM and the calibration line was linear up to 75 microM. The within-day accuracy and precision of the quality control samples (0.45, 1.0, 10 and 40 microM) were better than 15 and 13%, respectively. The between-day accuracy and precision were less than 3, 20%, respectively. The recovery of monoHER (using quality control concentrations) was concentration independent and ranged from 90.5 to 95.3% except for the lowest quality control, 0.45 microM, of which the recovery was 85%. The concentration of monoHER in plasma decreased with 10% when stored at -80 degrees C for one month and with 20% when stored at -20 degrees C for 3 weeks. The repeated injection of monoHER in aliquots of 10 microM, stored in the autosampler tray (4 degrees C), showed a consistent decrease during a run: 15% over 24 h. To compensate for this decrease, sample duplicates were analysed in a mirror image sequence.