Capillary liquid chromatography with UV detection using N,N-diethyl dithiocarbamate for determining platinum-based antitumor drugs in plasma.

A capillary liquid chromatography with UV detection (CLC-UV) system has been developed for determining platinum-based antitumor drugs (e.g., cisplatin, carboplatin, and nedaplatin) in plasma based on the pre-column derivatization of platinum with N,N-diethyl dithiocarbamate (DDTC). The chelated platinum separation was carried out on a capillary column (Inertsil ODS-3, 150 mm × 0.3 mm i.d., 3 µm) using an acetonitrile-water mixture (8:2, v/v) as a mobile phase that flowed at 5.0 µL/min. Detection was carried out by absorbance at 254 nm. Chromatographic peak height was found to be linearly related to the spiked concentration of nedaplatin in the blank control plasma from 5.0 ng/mL to 15 µg/mL (r(2)>0.998). The repeatability (n=5) of the chromatographic peak height for 2.5 µg/mL nedaplatin was 2.6% relative standard deviation (R.S.D.). The CLC-UV system, which required only 20 µL of plasma sample, was applied to the determination of total and free form platinum-based antitumor drugs in plasma after injection into rats. The recovery rates (n=5) of total and free form nedaplatin in plasma were 98% and 99%, respectively, and these repeatability were 2.4% R.S.D. and 3.1% R.S.D., respectively. In addition, the recovery rates (n=5) of total and free form carboplatin in plasma were 99% and 99%, respectively, and these repeatability were 2.9% R.S.D. and 0.24% R.S.D., respectively. The concentration-time profiles of total and free form nedaplatin in rat plasma were monitored to determine the pharmacokinetic parameters.