High performance liquid chromatography with UV detection for the simultaneous determination of sympathomimetic amines using 4‐(4,5‐diphenyl‐1H‐imidazole‐2‐yl)benzoyl chloride as a label

Abstract

A high performance liquid chromatographic method has been developed for the simultaneous determination of (+/-) fenfluramine (Fen) and phentermine (Phen) in addition to three other sympathomimetic amines-ephedrine (E), norephedrine (NE) and 2-phenylethylamine (2-PEA), using cyclohexylamine (CX) as an internal standard in plasma. The compounds were derivatized with 4-(4,5-diphenyl-1H-imidazole-2-yl)benzoyl chloride (DIB-Cl) to give the DIB-derivatives. The derivatives were then separated using an isocratic HPLC system with UV detection. The limits of detection for Fen, Phen, E, NE and 2-PEA in plasma ranged from 0.32 to 22.9 pmol on column at a signal-to-noise ratio of 3. The recoveries following alkaline extraction from plasma samples of known concentrations were found to be more than 94% for the studied compounds. This method might be useful for the screening of the studied sympathomimetic amines in human plasma samples in forensic as well as toxicological studies. Furthermore, the developed method was modified for the simultaneous determination of Fen and Phen in human and rat plasma using fluoxetine as an internal standard. The methods are reproducible and precise. Finally, the two drugs were administered intraperitoneally to rats in combination, and their plasma levels over the investigated time course were successfully determined.

Analytical Studies on the Development of High-Performance Liquid Chromatographic Methods with Fluorescence or Chemiluminescence Detections and Their Practical Applications

“…The analytes labeled with DIB-Cl were also determined by an HPLC-UV method. 61 However, since the sensitivity of these methods was not enough to determine Fen in hair, an HPLC-FL method with DIB-Cl labeling was examined. In this study, Fen and its active metabolite of norfenfluramine (Norf) were measured as target compounds.…”

Lophine derivatives as versatile analytical tools

“…For the convenience, simultaneous determination of some sympathomimetic amines with HPLC-UV was examined (Kaddoumi et al, 2001b); the compounds examined were fenfluramine, phentermine, ephedrine, norephedrine, 2-phenylethylamine and cyclohexylamine as an internal standard. DIB derivatives of these compounds were well separated isocratically and detected at 325 nm.…”