Analytical Sciences

Abstract − Analytical Sciences, 19(2), 317 (2003).

Determination of Midodrine in Human Plasma by High-Performance Liquid Chromatography with Fluorescence Detection
Hideyuki YOSHIDA, Yuki OHNO, Kenichiro YOSHIKUNI, Kenichiro TODOROKI, Hitoshi NOHTA, and Masatoshi YAMAGUCHI 
Faculty of Pharmaceutical Sciences, Fukuoka University, Nanakuma, Johnan, Fukuoka 814-0180, Japan
A simple and sensitive fluorometric high-performance liquid chromatographic method was developed for the determination of midodrine in human plasma. After liquid-liquid extraction from plasma, the drug and 2-phenylglycinol (internal standard) were converted into the corresponding fluorescent derivatives by reaction with 3,4-dihydro-6,7-dimethoxy-4-methyl-3-oxoquinoxaline-2-carbonyl chloride, a fluorescence derivatization reagent for amines. The derivatives were separated within 30 min on a reversed-phase column using isocratic elution with acetonitrile-methanol-water (10:30:60, v/v) and were detected spectrofluorometrically at 485 nm with excitation at 400 nm. The detection limit for midodrine was 0.3 pmol (76 pg) per mL plasma at a signal-to-noise ratio of 3.